Here - Fifteenth International Conference on Numerical Combustion

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th
15 International Conference on
Numerical Combustion
Palais des Papes, Avignon, France
April 19-22, 2015
www.nc15.ecp.fr
Organized by Laboratoire EM2C
CNRS and CentraleSupélec
2 Organizing committee Organizing Committee
Denis Veynante (chair)
Matthieu Boileau
Nasser Darabiha
Sébastien Ducruix
Benoît Fiorina
Olivier Gicquel
Frédérique Laurent-Nègre
Brigitte Llobel
Franck Richecoeur
Nathalie Rodrigues
Philippe Scouflaire
Thomas Schmitt
Ronan Vicquelin
Laboratoire EM2C
UPR 288 CNRS and CentraleSupélec
Grande Voie des Vignes
92295 Châtenay-Malabry Cedex
France
http://www.em2c.ecp.fr
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. Conference sponsors 3 CONFERENCE SPONSORS
sponsors
Bronze sponsor
FLUIDYN France
7 boulevard de la Libération
93200 Saint-Denis - France
Contact: Dr. Amita Tripathi
email: [email protected]
Tél: +33 (0)1 42 43 16 66
Fax: +33 (0)1 42 43 50 33
Silver sponsors
NUMECA International
Ch. de la Hulpe 189 Terhulpse Steenweg
1170 Brussels - Belgium
Contact: Dr.-Ing. Jan E. Anker
Head - Combustion Modeling Group
Tel: +32 (0)2 642-2824
Fax: +32 (0)2 647 93 98
SGI Corporate Headquarters
900 North McCarthy Blvd.
Milpitas, CA 95035 - USA
Sales Contact: 1-800-800-7441
http://www.sgi.com/sales/askarep.html
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. Monday April 20th, 2015 4 Program summary: Monday April 20th, 2015 15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 5 Tuesday April 21st, 2015 Program summary: Tuesday April 21st, 2015 15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 6 Program summary: Wednesday April 22nd, 2015 Wednesday April 22nd, 2015 15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. Convention Center map 7 Palais des Papes
Convention Center map
Rooms
Level 0 (Convention Center entrance): Salle des Gardes
Level 1: Cellier Benoît XII
Level 2: Salle de la Paneterie, access to Cloître Benoît XII
Level 3: Salle du Conclave, Chambre du Trésorier, Cubiculaire, Grand Promenoir
Registration desk: Salle des Gardes (level 0)
Plenary lectures: Salle du Conclave (level 3)
Coffee breaks, lunches: Salle des Gardes (level 0), Salle de la Paneterie, Cloître Benoît XII (level 2)
Gala dinner: Salle Jeanne Laurent (5 mn walk from Palais des Papes)
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 12 h 00 - 13 h 30
10 h 00 - 12 h 00
9 h 30 - 10 h 00
8 h 30 - 9 h 30
8 h 15 - 8 h 30
Session 4 (Paneterie)
Plenary lecture: Prof. Luc VERVISCH (CORIA, France)
Welcome
Session 3 (Trésorier)
! RANS-based modeling and
uncertainty quantification of soot
formation in flames, H. Koo,
M. Mueller, V. Raman, B. Dally
Session 5 (Promenoir)
!Theoretical, numerical, and
modeling issues in LES, V. Raman
Org.: V. Raman and M. Mueller
Mini-symposium
MS1 (1/2)
Large eddy simulation:
Challenges and
opportunities
!Simple and fast integration method
for stiff chemical kinetic ODEs,
Y. Morii, H. Terashima, M. Koshi,
T. Shimizu, E.Shima
Chair: V. Giovangigli
Contributed presentations
CP2 (1/2)
Numerical methods
Org.: F. Zhang, H. Bockhorn,
C.O. Paschereit, W. Schröder,
J. Janicka
Mini-symposium
MS2
Combustion Noise
Coffee Break
Lunch
! Modelling of flame lift-off evolution:
numerical implementation of densitypressure coupling, Z. Chen,
S. Ruan, N. Swaminathan
! G-equation based modelling of
partially premixed compressible
reactive flows, L. Gastaldo,
J.C. Latché
Org.: H. Schmidt
Session 6 (Cubiculaire)
!
! Trivariate chemistry model for the
simulation of high Karlovitz
premixed turbulent flames,
B. Savard, G. Blanquart
! Flamelet/progress variable CFD
modeling of high-pressure partial
oxidation flame, M. Vascellari,
H. Xu, S. Hartl, C. Hasse
! Introduction of unsteadiness and
small-scale resolution into steadystate reacting-flow solvers using
LEM3D, S. Sannan, A.R. Kerstein
! Comparison between ODT and
DNS for ethylene/air auto-ignition,
A. Abdelsamie, D. Thévenin
!The representative interactive
linear-eddy model (RILEM) for
regime-independent turbulent nonpremixed combustion modeling
combustion,
T. Lackman, A.R. Kerstein,
M. Oevermann
!Reduction of chemical
mechanisms for aviation fuels with
RCCE, W. Jones, P. Koniavitis,
S. Rigopoulos
! Investigation of corrugated
premixed methane-air flame
structure using REDIM,
A. Neagos, V. Bykov, U. Maas
!On the benefits of using LEM- and
ODT-based approaches in
numerical combustion, H. Schmidt
!Extraction of Chemical kinetics
insights with special CSP data,
S. Lam
Mini-symposium
MS3
CP3 (1/3)
Advances in linear-eddy and
Kinetics reduction and
one-dimensional-turbulence
tabulation
modeling
Chair: C. Westbrook
Simulation of turbulent flames: from high-performance computing to low-order stochastic models for process control
Session 2 (Cellier)
!Direct combustion noise of
premixed flames: experiments and
simulation using compressible LES
and DNS, F. Zhang, H. Nawroth,
! Using LES of ignition, quenching
P. Habisreuther, J. Moeck,
and instabilities to design future gas
C.O.
Paschereit, H. Bockhorn
turbines, T. Poinsot, B. Cuenot,
! Physics-based preconditioning and
! Lewis number effects in turbulent
L. Gicquel, G. Staffelbach,
dual timestepping for stiff
nonpremixed sooting flames,
A. Dauptain, F. Duchaine
combustion problems with detailed ! A hybrid approach to predict
A. Attili, F. Bisetti, M.E. Mueller,
chemical mechanisms, M. Hansen, combustion noise of premixed
H. Pitsch
J.
Sutherland
flames, A. Hosseinzadeh, G. Geiser,
! Assessment of LES combustion
J. Janicka, W. Schröder
models, H. Pitsch, P. Trisjono
! Large eddy simulation of soot
!Adaptation in time and space for
formation in an oxy-coal combustor, !
multi-scale combustion fronts with
!LES based simulations of
D. Lignell, A. Josephson, B. Isaac,
error control based on operator
combustion noise in a helicopter
T. Fletcher
splitting and multiresolution,
engine, T. Livebardon, L. Gicquel,
M. Duarte, S. Descombes,
T. Poinsot, E. Bouty
M. Massot, C. Tenaud, S. Candel
! Sensitivity of soot production to
gaseous kinetic models in LES of
! Estimating indirect combustion
aero-engine combustors,
! A new approach to secure scalar
noise in nozzle flows with a 2D
B. Franzelli, E. Riber, B. Cuenot,
boundedness in flame simulation
analytical model, J. Zheng, M. Huet,
M. Ihme
with high-order spectral difference
A. Giauque, F. Cléro, S. Ducruix
methods on unstructured meshes,
E. Bossenec, G. Lodato,
! PDF Modelling of Soot Emissions,
P. Domingo, L. Vervisch
M.A. Schiener, R.P. Lindstedt
!Accounting for strain-rate effects in
soot modeling of turbulent flames,
B. Franzelli, A. Cuocci, A. Stagni,
C. Saggese, A. Frassoldati,
T. Faravelli, M. Ihme
Chair: S. Dworkin
Contributed Presentations
CP1 (1/2)
Soot
Session 1 (Conclave)
Monday April 20th, 2015 8 Detailed program: Monday April 20th, 2015 15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 15 h 30 - 16 h 00
13 h 30 - 15 h 30
! The challenge of pollutant
emission predictions in realistic
burners,
V. Moureau, G. Lartigue
!Validation of multi-physics LES
against sparse data, M. Mueller
!
! An efficient operator splitting
Monte Carlo for aerosol dynamics
simulation with application to soot
formation, A. Abdelgadir, K. Zhou,
F. Bisetti
! Development of a unique function
for soot surface reactivity while
oxidation and surface growth in
laminar diffusion flames,
A. Khosousi, S. Dworkin
! Modeling soot formation and
oxidation in laminar premixed
flames using the method of
moments and a continuous
reconstruction of the soot number
density function,
A. Wick, T.T. Nguyen, F. LaurentNègre, M. Massot, R.O. Fox,
H. Pitsch
! Design optimization with LES,
Q. Wang
! Modeling the soot particle size
distribution in flames using an
extended quadrature method of
moments approach, S. Salenbauch, ! Data-driven modeling for LES,
A. Cuocci, T. Faravelli, C. Hasse
K. Duraisamy
!Heterogeneous PAH dimerization
as an Important contributor to soot
nucleation, N. Eaves, S. Dworkin,
M. Thomson
Org.: V. Raman and M. Mueller
Mini-symposium
MS1 (2/2)
Large eddy simulation:
Challenges and
opportunities
Contributed Presentations
CP1 (2/2)
Soot
Chair: C. Shaddix
Session 2 (Cellier)
!Assessment of double conditioning
of reactive scalar transport
equations for HCCI, F. Salehi,
M. Talei, E.R. Hawkes,
A. Bhagatwala, J.H. Chen, S. Kook
! Using large eddy simulation (LES)
for pollutant prediction in turbulent
flames, T. Jaravel, E. Riber,
B. Cuenot
!Application of a regularization
method to the choice of the strain
parameter in LES of a turbulent
premixed jet burner, K. Kleinheinz,
E. Knudsen, E.R. Hawkes, H. Pitsch
!Compressible combustion and
nonlinear dynamics for
thermoacoustic analysis, C.T. Lee,
S. Cant
! Effect of compressibility in the
flashback of premixed flames in
confined channels, M. Hassanaly,
H. Koo, V. Raman
! Simulation of high-pressure
turbulent mixing and reacting real
gas flows, M. Pfitzner, H. Müller
! Reduced schemes in combustion,
A. Felden, B. Cuenot, E. Riber
!Using genetic algorithms for
optimizing reduced chemicalscheme for turbulent flames
simulation, N. Jaouen, P. Domingo,
L. Vervisch
!An implicit, density-based
algorithm for coupled simulations of
arbitrary gas mixtures, F. di Mare,
L. di Mare
Org.: F. di Mare
Mini-symposium
MS5
Numerical methods for
compressible combustion
! A reduced and optimized chemical
mechanism for n-dodecane
oxidation, L. Cai, L.C. Kröger,
H. Pitsch
! An adaptive strategy for the
! Towards an integrated approach to efficient implementation of complex
realistic engine modeling with large- chemistry in turbulent flame
scale computing, S. Aithal
simulations, Y. Liang, S. Pope,
P. Pepiot
!
Coffee Break
! Uncertainties in theoretically
predicted elementary rate
coefficients , S. Klippenstein
! A DNS study of ignition
characteristics of a lean H2/air
mixture under HCCI conditions
within an enclosed geometry
including wall heat transfer, M.
Bolla, M. Schmitt, E.R. Hawkes,
! Probabilistic inference of reaction
rate parameters based on summary K. Boulouchos
statistics, M. Khalil, H. Najm
! Investigations on pressure wave
generation and chemical kinetics
! Uncertainty quantification in the
during end-gas autoignition on
oxidation of vinyl radical,
knocking combustion, H. Terashima,
F. Goldsmith
M. Koshi,
! Correlated uncertainty
! Prediction of super-knock in a
quantification: application to
downsized spark-ignition engine
complex chemical kinetics
using Large-Eddy Simulation,
mechanisms,
K. Truffin, A. Robert, O. Colin,
J. Sutton, W. Guo, M. Katsoulakis,
C. Angelberger
D. Vlachos
! Combining theory and experiment
to reduce uncertainties in the
derivation of phenomenological rate
coefficients for combustion systems,
A. Tomlin, R. Shannon, P. Seakins,
M. Pilling, M. Blitz, S. Roberson
A. Tomlin
Chair: D. Goussis
Mini-symposium
MS4 (1/4)
CP3 (2/3)
CP4
Uncertainty quantification in
Internal
combustion
engines
computational combustion
tabulation
Chair: O. Colin
Org.: H. Najm, M. Frenklach,
Monday April 20th, 2015 Detailed program: Monday April 20th, 2015 9 18 h 00 - 18 h 30
16 h 00 - 18 h 00
! Direct numerical simulation of low
Mach number combustion beyond
petascale, C. Frouzakis,
A. Tomboulides, S. Kerkemeier,
P. Fisher
! Legacy codes and the jump to
exascale : Fluid dynamics
simulation with AVBP and HPC,
G. Staffelbach, O. Vermorel,
S. Jaure, C. Fournier, I. D'Ast,
E. Oseret
!Combustion simulation on nextgeneration architectures, J. Bell
! Toward large-eddy simulation of
complex burners with exascale
super-computers: a few challenges
and solutions, V. Moureau
!Legion as a programming model
for combustion simulation at the
exascale, J. Chen, M. Bauer,
S. Treichler, A. Aiken, A. Bhagatwala
Org.: J. Chen and R. Sankaran
! Statistical calibration of simplified
chemical mechanisms for Diesel
engine combustion, L. Hakim,
G. Lacaze, M. Khalil, H. Najm,
J. Oefelein
! Uncertainty quantification of the
rate parameters of the syngas
combustion system, T. Varga,
C. Olm, I.G. Zsély, T. Nagy,
E. Valkó R. Palvolgyi, H.J. Curran,
T. Turányi
! Combining theoretical and
experimental data in uncertainty
quantification across multiple
scales, M. Burke
! Comparison of probabilistic and
deterministic frameworks of
uncertainty quantification,
M. Frenklach, A. Packard, J. Sacks,
R. Pablo, G. Garcia-Donato
A. Tomlin
! Flow curvature method applied to
dynamical systems analysis,
J.M. Ginoux
! Optimal dimension of the
combustion mechanism in the
ignition problem, V. Bykov,
V. Gol'dshtein, U. Maas
!Analytical prediction of syngas
induction times, P. Boivin,
A. Sanchez, F. Williams
!The developing explosive
dynamics in the vicinity of the third
explosion limit of H2/air,
E.A. Tingas, T. Turanyi, D. Goussis
! Uncertainties in predicting the
ignition properties of biofuels: what
constraints can measurements
provide?, A. Tomlin, E. Agbro
!How details of fuel molecular
structure can accelerate or retard
autoignition, C. Westbrook
Org.: M. Valorani
!Three-dimensional structure of
hypergolic ignition process for
hydrazine/nitrogen dioxide un-like
doublet impinging gas jets,
Y. Daimon, H. Tani, H. Terashima,
M. Koshi
! Computational modeling of boron
particle fueled ducted rocket
combustion chambers, B. Kalpakli,
! A consistent approach for coupling E. Acar
the devolatilization of coal particles
with tabulated chemistry,
!Numerical simulation of turbulent
R. Knappstein, A. Ketelheun,
combustion between a hydrogen jet
G. Künne, J. Köser, A. Dreizler,
and a supersonic vitiated air
A. Sadiki, J. Janicka
crossflow, A. Techer, G. Lehnasch,
A. Mura
! Macropore growth in char particles
under different gasification
!Numerical investigation of
conditions , K. Wittig, A. Richter,
transverse hydrogen jet into
M. Kestel, P. Nikrityuk, B. Meyer
supersonic crossflow using
detached eddy simulation,
L. Zhaoyang, W. Zhenguo,
!How does turbulent fluid motion
S. Mingbo, W. Hongbo
influence heterogeneous
combustion?, J. Krüger, N. Haugen,
T. Løvås
! Numerical study of flame dynamic
characteristics in a supersonic
combustor with dual cavity, Y. Yixin,
! Application of a skeletal kinetic
mechanism on LES of a pulverized W. Hongbo, W. Zhenguo, S. Mingbo
coal jet flame, S. Ahn, H. Watanabe,
K. Tanno, N. Hashimoto
! Numerical simulation on detonation
initiation and propagation in
supersonic combustible mixtures
with nonuniform velocities and
species, X. Cai, J. Liang, Z. Lin,
R. Deiterding, Y. Che
! A modified two-step model for
devolatilization, A. Richards,
T.H. Fletcher
!Adaptive kinetic model for coal
devolatilization in oxy-coal
combustion conditions, S. Iavarone,
C. Galletti, F. Contino, L. Tognotti,
A. Parente and P.J. Smith
Chair: C. Fureby
Mini-symposium
Mini-symposium
MS4 (2/4)
MS7 (1/2)
CP7
CP6
Uncertainty quantification in Diagnostics for auto-ignition
Rocket engines, ramjets,
Coal
combustion
processes
scramjets
Chair C. Hasse
! Bayesian inference of chemical
! Large eddy simulation of turbulent
kinetic models from proposed
combustion with a dynamic second- ! Physical and algorithmic
reactions, N. Galagali, Y. Marzouk
order moment closure model,
approaches to numerical
K. Luo, J. Yang, Y. Bai, J. Fan
combustion at the exascale, S. Cant !Region of influence-based
sensitivity analysis in turbulent
! A dynamically adaptive combustion
combustion, V. Carey, R. Moser
framework for the general
description of complex flame
configurations,
H. Wu, Y.C. See, Q. Wang, M. Ihme
! A dynamic sub-grid model for
turbulent combustion based on
conditional averaging,
G. R. Hendra, M.M Salehi,
W.K. Bushe
! Analysis of a dynamic flame
wrinkling factor model for large eddy
simulations of turbulent premixed
combustion, P. Stefanin-Volpiani,
T. Schmitt, D. Veynante
! Modelling of lean premixed flames
based on a new artificial thickened
flame framework, K. Vogiatzaki,
S. Navarro-Martinez, S. Hong,
S. Shanbhogue, A. Ghoniem
!Modelling of the subgrid scale
wrinkling factor for large-eddy
simulation of turbulent premixed
combustion, F. Thiesset, G.
Maurice, F. Halter, N. Mazellier,
C. Chauveau, I. Gökalp
Chair: O. Gicquel
Mini-symposium
MS6 (1/2)
Towards exascale
simulation of turbulent
combustion
Session 2 (Cellier)
CP5 (1/6)
Turbulent combustion
Monday April 20th, 2015 10 Detailed program: Monday April 20th, 2015 15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 12 h 00 - 13 h 30
10 h 00 - 12 h 00
! Using GPUs to accelerating
nonstiff and stiff chemical kinetics in
combustion simulations,
K. Niemeyer
! The framework of multiple mapping ! GPU based chemistry acceleration
conditioning, its applications and
for reacting flow simulations , J. Lee,
prospects, A. Klimenko, M. Cleary,
V. Sankaran
B. Sundaram, L. Dialameh
! Accelerating combustion modeling
!Radiation effects on a turbulent
with the Intel Xeon Phi, C. Stone
premixed syngas flame,
S. Karimkashi, M. Bolla, H. Wang,
E.R. Hawkes, H.G. Im, P.G. Arias,
M. Talei
!Analysis of approximate
deconvolution strategies and explicit
filtering for LES of turbulent flames, ! Efficient abstractions for exascale
P. Domingo, L. Vervisch
software design, J. Sutherland
! Chemical source term modeling in
LES of reacting flows using
deconvolution method, Q. Wang,
M. Ihme
Org.: J. Chen and R. Sankaran
Mini-symposium
MS6 (2/2)
Towards exascale
simulation of turbulent
combustion
!Reacting flow simulation
framework for heterogeneous and
many-core architectures,
R. Sankaran, B.J. Lee, H. Im
! Radiative properties of molecular
combustion products and of some
hydrocarbons: state of the art,
P. Rivière, A. Soufiani
!Numerical study of alkane-air
spray combustion, C. Nicoli,
P. Haldenwang, B. Denet
Chair: M. Arienti
Lunch
! Analysis of multi-phase material
model for Al/AlOx droplet, K. Lee,
D.S. Stewart
! Spray modeling using a method of
moment approach with droplet size
! LES analysis of the influence of the distribution reconstruction,
turbulence intensity on the critical
M. Pollack, S. Salenbauch,
ignition energy of a lean
C. Hasse
methane/air flame, S. Mouriaux,
O. Colin, B. Renou, D. Veynante
! Counter-flow spray pulsated
flames: from experimental
! The flame consumption speed –
measurements to numerical
comparison of theory and numerical simulation , J.C. Brändle de Motta,
simulations, G. Giannakopoulos,
M. Boileau, L. Zimmer, B. Robbes,
C. Frouzakis, M. Matalon,
F. Laurent-Nègre, M. Massot
A. Tomboulides
! Large eddy simulations of
! A statistical model to predict
polydisperse turbulent n-heptane
ignition probability, L. Esclapez,
spray flames with a dynamic ATF
E. Riber, B. Cuenot
procedure coupled with the FGM
chemistry reduction method,
F.L. Sacomano Filho, M. Chrigui,
! A method for predicting sensitive
rate coefficients with high accuracy A. Sadiki, J. Janicka
tested for the H2/CO/O2-system,
T. Methling, M. Braun-Unkhoff,
! Toward the fully realizable large
U. Riedel
eddy simulation of disperse phase
flows: Eulerian kinetic modelling and
associated numerical methods,
!
M. Sabat, A. Vié, A. Larat,
M. Massot
! Direct numerical simulations of
kernel growth of turbulent premixed
syngas/air flames,
G. Giannakopoulos, C. Frouzakis,
M. Matalon, A. Tomboulides
Chair A. Trouvé
Contributed presentations Contributed presentations
CP8 (1/2)
CP9 (1/2)
Ignition / quenching
Two-phase flows
Coffee Break
Org.: A. Kapila and
D. Schwendeman
Mini-symposium
MS8
Modeling and computation
of detonations in highenergy explosives
!A discrete model of gas
combustion in porous media,
F. Sirotkin, R. Fursenko, S. Minaev
Chair: A. Parente
CP10 (1/2)
New technologies
!Large-eddy simulation of a MILD
combustion burner using conditional
source-term estimation , J. Labahn,
C. Devaud
! Direct numerical simulation of
MILD combustion, U. Göktolga,
J. van Oijen, P. de Goey
! The effect of the three! Coupled simulations of condensed- dimensionality of the flame front
phase explosives and elastic-plastic inside a radial-flow porous burner –
solids, L. Michael, N. Nikiforakis
a detailed DPLS numerical study,
I. Dinkov, P. Habisreuther,
H. Bockhorn
! Propagation of detonations in
curved geometries of compliantly
confined solid explosives ,
! Lean hydrogen flames in a narrow
E. Ioannou, L. Michael,
adiabatic channel, C. Jiménez,
N. Nikiforakis
D. Fernández-Galisteo,
V. Kurdyumov
! Application of two-dimensional
shock-fitting to detonation
! A numerical investigation of
propagation in high explosives,
heterogeneous/homogeneous
T. Aslam, C. Romick
combustion of n-dodecane over Pt
for mcrocombustion, E. Tolmachoff,
A. Booth, I. Lee
!Sensitivity of run-to-detonation
distance in practical explosives,
J Gambino, D. Schwendeman,
A. Kapila
The hydrodynamic theory of premixed flames: laminar tot turbulent propagation
!Spectral model of premixed
turbulent flame, S. Rashkovskiy
Chair: B. Fiorina
CP5 (2/6)
Plenary lecture: Prof. Moshe MATALON (University of Illinois, Urbana-Champaign, USA)
Session 2 (Cellier)
9 h 30 - 10 h 00
8 h 30 - 9 h 30
Tuesday April 21st, 2015 Detailed program: Tuesday April 21st, 2015 11 15 h 30 - 16 h 00
13 h 30 - 15 h 30
Org.: F. Duchaine and L. Gicquel
Mini-symposium
MS9 (1/2)
High-fidelity coupled
simulation of reacting
systems
Session 2 (Cellier)
! Modal analysis of reacting jet in
cross flow using direct numerical
simulations, T. Sayadi, S. Lyra,
C. Hamman, H. Kolla, P. Schmid,
J.H. Chen
! Direct numerical simulation of a
turbulent lifted DME jet flame in a
heated coflow at elevated pressure,
Y. Minamoto, J.H. Chen
spontaneous flame propagation
under reactivity controlled
compression ignition conditions,
A. Bhagatwala, R. Sankaran,
S. Kokjohn, J.H. Chen
!Analysis of large-eddy simulations
of laboratory-scale fire, M. Rochoux,
B. Cuenot, F. Duchaine, E. Riber,
D. Veynante, N. Darabiha
!An a priori DNS study of molecular !Large eddy simulation and the
mixing models in a planar stationary filtered probability density function
premixed flame, X. Zhao, H. Kolla,
method, W. Jones
J.H. Chen
! Heterogeneous multi-scale LES
! 3D DNS of methane-air turbulent
using skeletal reaction mechanisms,
premixed planar flame in thin
C. Fureby, N. Zettervall,
reaction zones, B. Yenerdag,
K. Nordin-Bates
Y. Naka, M. Shimura, M. Tanahashi
! Coupling approach to account for
!A peta-scale direct numerical
heat losses in a practical
simulation study on pollutant
combustor, D. Mira, M. Zavala-Ake,
formation in turbulent premixed
S. Gövert, M. Vazquez,
flames, P. Trisjono, H. Pitsch
G. Houzeaux
Chair: S. Menon
CP5 (3/6)
! Numerical simulation of shock
wave dynamics internal ballistics of
gun, M. Chirame, D. Pradhan,
S. Naik
! Flame acceleration in channels
with cold walls, C. Dion,
B. Demirgok, V. Akkerman,
D. Valley, V. Bychkov
Chair: A. Matsuo
! Modeling and simulation of a
dense evaporating spray,
F. Doisneau, M. Arienti, J. Oefelein
! Detonation shock propagation
!Compressibility effects in the initial through nitromethane embedded
transient of high-pressure Diesel
metal foam, B. Lieberthal,
injection, M. Arienti, M. Sussman
D.S. Stewart
S. Rashkovskiy, A. Dolgoborodov
! Numerical simulations of kerosene
spray atomization with various
! Simulations of compressible gashybrid breakup models, T. Liu,
dust flows, E. Oran, R. Houim
L. Hu, Y. Wu, D. Zhao, G. Wang
! A monotonic mixing-describing
composition-space variable for the
flamelet formulation of spray flames,
B. Franzelli, A. Vié, M. Ihme
! Symmetric Baer and Nunziato
model, R. Saurel
!Numerical investigation of sheardriven primary breakup of liquid fuel !3D simulation of discrete
flows, C. Bilger, T. Pringuey,
combustion waves in mechanically
R.S. Cant
activated powder mixtures,
!Development of a turbulent liquid
flux model for Eulerian-Eulerian
multiphase flow simulations,
S. Puggelli, A. Andreini,
C. Blanchini, B. Facchini,
F.X. Demoulin
Coffee Break
! Adjoint-based sensitivity for
understanding chemistry modeling,
V. Raman, K. Braman, T. Oliver
!Effect of uncertainties in detailed
chemistry on combustion model
parameters, N. Dumont,
R. Vicquelin, O. Gicquel
! Combustion properties of H2/CO
mixtures: consistent chemical
mechanism from collaborative data
processing, N. Slavinskaia,
U. Riedel, J.H. Starcke
! Facilitating uncertainty
quantification for large, detailed
reaction mechanisms, R. West,
S. S. Goldsborough, A. Fridlyand
! Handling model error in the
calibration of physical models,
H. Najm, K. Sargsyan, R. Ghaneim
A. Tomlin
Chair: P. Haldenwang
!
! Computational modeling of plasma
assisted combustion in gas turbines
for electric power generation,
A. Ehn, J. Zhu, P. Petersson, Z. Li,
M. Alden, C. Fureby, T. Hurtig,
N. Zettervall, A. Larsson, J. Larfeldt
! Simulation of turbulent premixed
combustion with a self-consistent
plasma model for initiation,
H. Sitaraman, R. Grout
! Application of a two-fluid plasma
model to the simulation of premixed
flames under electric fields,
T. Casey, P. Arias, J. Han, M. Belhi,
F. Bisetti, H. Im, J.Y. Chen
! Steady laminar one-dimensional
flame solvers for modelling ions in
flames, B.J. Lee, M.S. Cha, H. Im,
S.H. Chung
!Numerical aspects of the
shockless explosion combustion,
P. Berndt, R. Klein, C.O. Paschereit
Chair: P. Domingo
Mini-symposium
Contributed presentations Contributed presentations Contributed presentations
MS4 (3/4)
CP9 (2/2)
CP11 (1/3)
CP10 (2/2)
Uncertainty quantification in
Two-phase flows
Detonation
New technologies
Tuesday April 21st, 2015 12 Detailed program: Tuesday April 21st, 2015 15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 19 h 30 - 23 h 00
18 h 00 - 18 h 30
16 h 00 - 18 h 00
!A 3D coupled approach for the
thermal design of aero-engine
combustor liners, A. Andreini,
B. Facchini, L. Mazzei
! LES flamelet-progress variable
modeling of a turbulent piloted
dimethyl ether flame, S. Popp,
F. Hunger, S. Hartl, D. Messig,
B. Coriton, J. Franck, F. Fuest,
C. Hasse
! DNS and experiments of H2/He
jets in a vitiated turbulent crossflow,
! Towards coupled simulation of
S. Lyra, B. Wilde, H. Kolla,
aero-engines HP system using
T.C. Lieuwen, J.H. Chen
industrial CFD solvers, P. Legrenzi
! Numerical simulation of NOx
formation in syngas combustion,
H. Watanabe, T. Kawai, S.Y. Ahn
!Turbulent diffusion flame modelling ! Automatic determination of the
in Large Eddy Simulation (LES),
coupling period in unsteady
F. Shum-Kivan, B. Cuenot, E. Riber conjugate heat transfer. Application
to large eddy simulation of flamewall interaction, C. Koren,
! LES combustion modelling of the
R. Vicquelin, O. Gicquel
dynamics of turbulent pulsed
premixed flames, A. Chatelier,
R. Mercier, N. Bertier, B. Fiorina
! Aerothermal prediction of an
aeronautical combustion chamber
based on the coupling of large eddy
! DNS of high turbulence intensity
simulation, solid conduction and
premixed methane-air flames in a
radiation numerical solvers,
3D inflow-outflow configuration,
S. Berger, F. Duchaine, L. Gicquel,
G. Nivarti, S. Cant
S. Richard
Org.: F. Duchaine and L. Gicquel
Mini-symposium
MS9 (2/2)
High-fidelity coupled
simulation of reacting
systems
CP5 (4/6)
Chair: W. Jones
Session 2 (Cellier)
!
! Reducing chemistry table sizes by
using polynomial functions,
W. Leudesdorff, A. Ketelheun,
J. Janicka
Chair: P. Pepiot
! Investigation of the effect of
correlated uncertain rate
parameters on a model of hydrogen
combustion using a generalized
HDMR method, E. Valkó, A. Tomlin,
T. Varga, T. Turányi
! Numerical investigation of ignition ! From fully premixed to highly
in laminar methane/LOx flamelet at stratified combustion using hybrid
supercritical pressures,
transported tabulated chemistry,
P.E. Lapenna, P.P. Ciottoli, F. Creta, B. Duboc, G. Ribert, P. Domingo
M. Valorani
!Comparative analysis of kinetic
! Impact of pilot injections on ignition mechanism reduction methods
behaviour at low in-cylinder
within the tabulation of dynamic
temperatures from extreme miller
adaptive chemistry framework,
valve timing in a heavy-Duty Diesel F. Contino, T. Lucchini, S. Backaert,
engine, S. Pandurangi, Y.M. Wright, N. Bourgeois, A. Parente,
C. Brückner, P. Kyrtatos,
H. Jeanmart
K. Boulouchos
! Principal component transport in
! Regimes of auto-ignition in
turbulent combustion, T. Echekki,
homogeneous reactant mixtures
H. Mirgolbabaei
with temperature fluctuations,
H. Im, P. Pal, M. Wooldridge,
! Principal component analysis for
A. Mansfield
modelling turbulent premixed
flames, A. Coussement, O. Gicquel,
! Auto-ignition diagnostics using the B. Isaac, A. Parente
tangential stretching rate concept ,
M. Valorani, S. Paolucci
!
!The developing explosive
dynamics during the autoignition
of a DME/air mixture, E.A. Tingas,
D. Kyritsis, D. Goussis
Banquet
! Industrial & applied V/UQ for a
15MW coal-fired boiler, P. Smith,
S. Smith
! Optimal experimental design of
furan shock tube kinetic
experiments, D. Kim, F. Bisetti,
Q. Long, R. Tempone, A. Farooq,
A. Knio
! Uncertainty quantification of rate
rules for normal alkanes using
Bayesian analysis, L. Cai,
L.C. Kröger, V. Raman, H. Pitsch
!Needs and progress in assessing
the accuracy of LES, J. Oefelein,
G. Lacaze
A. Tomlin
Org.: M. Valorani
!
! Development of an unstructured
CFD solver for the modeling of
industrial furnaces, L. Romagnosi,
J.E. Anker, K. Claramunt, C. Hirsch
! A laboratory-scale downsizing
procedure for highly resolved LES
of large-scale combustion system,
B. Farcy, D. Midou, L. Vervisch,
P. Domingo
! Large eddy simulation of coal and
biomass co-firing, M. Rabacal,
M. Costa, A. Kempf
! Avoiding ring formation in cement
kilns, D. Lahaye
!Effect of particle shrinkage on the
biomass pyrolysis behavior in a hightemperature entrained-flow reactor,
X. Ku, T. Li, T. Løvås
Mini-symposium
Mini-symposium
MS4 (4/4)
MS7 (2/2)
CP3 (3/3)
CP12
Uncertainty quantification in Diagnostics for auto-ignition
Industrial furnaces
processes
tabulation
Chair: A. Kempf
Tuesday April 21st, 2015 Detailed program: Tuesday April 21st, 2015 13 15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 12 h 00 - 13 h 30
10 h 00 - 12 h 00
9 h 30 - 10 h 00
8 h 30 - 9 h 30
Plenary lecture: Dr. Joseph OEFELEIN (Sandia, USA)
Chair: A. Tomboulides
!Direct numerical simulation of an
igniting, turbulent jet with global nheptane chemistry at enginerelevant conditions, A. Krisman,
E.R. Hawkes, A. Bhagatwala,
! DNS investigation on thermoacoustic oscillation characteristics of J. Chen
turbulent swirling premixed flame in
a cuboid combustor, K. Aoki,
M. Shimura, Y. Naka, M. Tanahashi investigation of autoignition with
split fuel injection, D.H. Shin,
E. Richardson
! Gas expansion and shear layer
effects in turbulent premixed flames,
S. Schlimpert, A. Feldhusen,
!
J. H. Grimmen, B. Roidl, M. Meinke,
W. Schröder
! Effects of hydrogen added on the
ignition of iso-octane in a diffusion
! Large eddy simulation of
layer, Z. Li, Z. Chen
transverse modes in a swirled
kerosene/air combustor, A. Ghani,
! Predicting extinction in condensed
T. Poinsot, L. Gicquel
phase combustion in a counterflow
geometry, S. Koundinyan,
! Acoustically induced vortex core
D.S. Stewart, M. Matalon, J. Bdzil
flashback in a staged swirlstabilized combustor, C. Lapeyre,
! Large eddy simulation of extinction
M. Mazur, P. Scouflaire,
limits in two-dimensional plane
F. Richecoeur, S. Ducruix, T. Poinsot buoyant turbulent diffusion flames,
S. Vilfayeau, J. White, A. Trouvé
! Dynamical modeling of combustion
instabilities in liquid rocket engines,
M. Gonzalez-Flesca, T. Schmitt,
S. Ducruix, S. Candel
!Nonlinear stability study of a timedelayed thermoacoustic system,
X. Yang, A. Turan, S. Lei
Chair: T. Shimizu
Coffee Break
!A modeling study of the lowtemperature oxidation of n-hexane,
2-methyl-pentane and 3-methylpentane, Z. Serinyel, O. Herbinet,
R. Fournet, V. Warth,
F. Battin-Leclerc
! Transition state theory based semiautomatic generation of surface
reaction mechanisms, P. Kraus,
P. Lindstedt
! Predictive fire simulations with the
software ISIS, C. Lapuerta,
S. Suard, F. Babik, G. Boyer
! PoKiTT: an efficient, platform
agnostic package for
thermodynamics, kinetics, and
transport properties in reactive flow
simulations, N. Yonkee,
J. Sutherland
!
Lunch
! Tabulation strategies of partially
premixed dimethyl-ether flames,
S. Hartl, A. Zschutschke, D. Messig,
C. Hasse
Scalable parallel and
computationally-conservative
implementations of the conditional
moment closure model in large eddy ! Kinetic modeling of the combustion
simulations, H. Zhang,
of 2-methyl-2-butene, C.
A. Garmory, E. Mastorakos
Westbrook, P.A. Glaude, F. BattinLeclerc, O. Herbinet, O. Mathieu,
! A methodology for the integration
E. Petersen
of stiff chemical kinetics on GPUs
and application to the LES-PDF
! Comparison of the performance of
simulation of a turbulent nonseveral recent hydrogen and syngas
premixed flame, F. Sewerin,
combustion mechanisms, C. Olm,
S. Rigopoulos
I.G. Zsély, R. Pálvölgyi, T. Varga,
T. Nagy, H.J. Curran, T. Turányi
! Load balancing, dynamic
repartitioning, and data migration in ! Kinetic study of the combustion of
turbulent reactors' simulation,
phenolic tars from biomass,
P. Pisciuneri, E. Meneses, A. Zheng, M. Nowakowska, O. Herbinet,
A. Labrinidis, P. Chrysanthis, P. Givi A. Dufour, P.A. Glaude
Chair: N. Darabiha
Chair: G. Staffelbach
! Finite volume methods for evolving
surfaces, K. Mikula, P. Frolkovic,
M. Remesikova
! Regularized flux-based gradient for
level set methods, J. Hahn
!A flame surface tracking method
for calculating the premixed
combustion in engines,
P. Priesching
Org.: J. Hahn and P. Priesching
Mini-symposium
MS11
Surface evolution methods
in gasoline direct injection
combustion engines
! Simulation of turbulent premixed
combustion in turbocharged direct
injection gasoline engines using a
! Transported probability density
level set based flamelet model,
function modeling of pulverized coal D. Linse
combustion, X. Zhao
! Oxy-coal power boiler simulation
and validation through extreme
computing, P. Smith, J. Thornock,
Y. Wu, S. Smith, B. Isaac
! LES and RANS of pulverized coal
oxy-combustion in swirl burners,
A. Bogusławski, P. Warzecha
!Developing and validating an oxyfuel CFD modelling methodolody,
R. Knappstein, A. Kethelheun,
G. Kuenne, S. Farazi, M. Baroncelli,
A. Sadiki, H. Pitsch, J. Janicka
Org.: A. Sadiki and H. Pitsch
Mini-symposium
MS10
LES modeling of oxy-coal
combustion
Modeling and Simulation of Real-Fluid Thermodynamics and Transport in Advanced Combustion Systems
Session 2 (Cellier)
Contributed presentations Contributed presentations Contributed presentations Contributed presentations
CP13
CP8 (2/2)
CP14
CP15
Instabilities
Ignition / quenching
HPC / Software engineering
Kinetics
Wednesday April 22nd, 2015 14 Detailed program: Wednesday April 22nd, 2015 15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 15 h 30 - 16 h 00
13 h 30 - 15 h 30
! Challenging modeling strategies
for LES of non-adiabatic turbulent
stratified combustion, B. Fiorina,
R. Mercier, G. Kuenne,
A. Ketelheun, A. Advic, J. Janicka,
D. Geyer, A. Dreizler, E. Alenius,
C. Duwig, P. Trisjono, K. Kleinheinz,
S. Kang, H. Pitsch, F. Proch,
F. Cavallo-Marincola, A. Kempf
! Large-eddy simulation/probability
density function modelling of
Cambridge stratified flame,
H. Turkeri, M. Muradoglu
! Resolved flame LES of the
Cambridge stratified burner using
PFGM, F. Proch, A.M. Kempf
! Preferential diffusion effects in LES
of mild combustion with flamelet
generated manifolds ,
S.E. Abtahizadeh, R. Bastiaans,
J. van Oijen, P. de Goey
! Analysis of ignition regimes in
rapid compression machines,
M. Ihme, K. Grogan,
S. Goldsborough
! Direct numerical simulation of the
auto-ignition of turbulent
ethylene/air mixtures,
A. Abdelsamie, D. Thévenin
! LES simulation of reactive flow
with effective PDF models at a
minimal cost, Y. Ge, F. Ferraro,
M. Pfitzner
! DNS of plasma-assisted ignition in
quiescent and turbulent flow
conditions , M. Castela, B. Fiorina,
O. Gicquel, A. Coussement,
C. Laux, N. Darabiha
!
Chair: M. Matalon
! Propagation of premixed flames in
long narrow channels from a closed
end: transition from constant speed
to rapid acceleration, V. Kurdyumov,
M. Matalon
circular expanding premixed flames
in a lean quiescent hydrogen-air
mixture: Phenomenology and
detailed flame front analysis,
C. Altantzis, C. Frouzakis,
A. Tomboulides, K. Boulouchos
! Numerical study of interaction
between Darrieus-Landau instability
and spatially periodic shear flow,
D. Valiev, A. Gruber, C.K. Law,
J.H. Chen
! Diffusive-thermal instabilities in
premixed flames: stepwise ignitiontemperature kinetics, L. Kagan,
I. Brailovsky, P. Gordon,
G. Sivashinsky
! The analysis diffusional-thermal
stability of rich hydrogen-air
combustion waves in model with
detailed kinetic mechanisms,
V. Gubernov, A. Korsakova,
A. Kolobov, V. Bykov, U. Maas
!Transient response of a laminar
premixed flame to a radially
diverging/converging flow,
M. Sahafzadeh, L. Kostiuk,
S. Dworkin
Coffee Break
!Compressible mixing of liquid
fuels, A. Hernandez, S. Stekovic,
D.S. Stewart, A. Wass
! Development, validation and
application of a DNS approach for
heterogeneous reactive flows,
A. Chabane, K. Truffin, A. Nicolle,
F. Nicoud, C. Angelberger
!Large Eddy Simulation using
adaptive mesh refinement with a
multi-level subgrid scaled closure
for turbulent reacting flows,
B. Muralidharan, S. Menon
!High-Order CENO Finite Volume
Scheme for Large-Eddy Simulation
of Turbulent Reactive Flows,
L. Tobaldini Neto, C. Groth
!Ignition in a premixed propane/air
gas by turbulent jets of its exhaust
products, A. Ghorbani, S. Fischer,
G. Steinhilber, D. Markus, U. Maas
Chair: J. Sutherland
!Numerical and experimental
analysis of laminar and turbulent
oxy-fuel jet flames using a direct
comparison of the Rayleigh signal,
F. Hunger, M.F. Zulkifli,
B.A.O. Williams, F. Beyrau,
C. Hasse
! Fuel effects on bluff-body
stabilized turbulent premixed
flames, V. Katta, W. Roquemore
! LES of transcritical LOx/GH2
injection in a rocket engine,
L. Matuszewki, P. Gaillard,
V. Giovangigli
! The absence of a dense potential
core in transcritical injection,
D. Banuti, K. Hannemann
!Diffuse interface methods for
diffusion flame from subcritical to
supercritical pressure, P. Gaillard,
V. Giovangigli, L. Matuszewki
Chair: J. Oefelein
! Two-phase simulations of
TNT/Aluminium afterburning during
explosions, E. Fedina, C. Fureby
A. Kasimov, B. Emolaev
! Large Eddy Simulation of
transverse acoustic activity in a 42injector rocket engine, A. Urbano,
L. Selle, G. Staffelbach, B. Cuenot,
T. Schmitt, S. Ducruix, S. Candel
! Oscillatory combustion in a subscale liquid rocket chamber,
T. Shimizu, Y. Morii, Y. Mizobuchi,
Y. Numone, T. Tomita,
H. H. Kawashima, M. Hishida
! A compressible LEM-LES strategy
(CLEM-LES) for modeling turbulent
detonation propagation, B. Maxwell,
! Large eddy simulations of a
S. Falle, G. Sharpe, M. Radulescu
naturally unstable transcritical
coaxial injector, A. Coussement,
! Set-valued solutions for
T.
Schmitt, S. Ducruix, S. Candel,
detonations with losses,
Y. Nunome
R. Semenko, L. Faria,
!
! Weakly nonlinear detonations:
theory and numerics , L. Faria,
A. Kasimov, R. Rosales
!Three-dimensional simulations of
shock-induced combustion around a
spherical projectile with various
diameters, Y. Sakuragi, A. Matsuo
Chair: G. Lodato
Contributed presentations Contributed presentations Contributed presentations Contributed presentations
CP2 (2/2)
CP16
CP11 (2/3)
CP17
Numerical methods
Laminar flames
Detonation
Real gases effects
Org.: D. Markus, U. Maas,
D. Thévenin
Mini-symposium
MS12 (1/2)
Safety related ignition
process
Session 2 (Cellier)
Chair: E. Hawkes
CP5 (5/6)
Wednesday April 22nd, 2015 Detailed program: Wednesday April 22nd, 2015 15 16 h 00 - 18 h 00
!Ignition at sub-millimeter sized hot
particles: a numerical and
experimental study, D. Roth,
T. Häber, H. Bockhorn
!Numerical investigation of ignition
over heated spheres,
J. Melguizo-Gavilanes, J. Shepherd
!
! Sensitivity of internal flow
dynamics and boundary conditions
on a turbulent opposed jet flame
configuration, A. Ruiz, G. Lacaze,
B. Coriton, J. Franck, J. Oefelein
! Analysis of natural gas fired
furnaces with different oxygen
enrichments, R. Prieler, M. Demuth,
C. Hochenauer
! Methanol ignition by a line energy
source embedded in a wall,
! Implicit large-eddy simulation of a M. Sanchez-Sanz,
Bunsen-like burner with multi-scale E. Fernandez-Tarrazo, A. Sanchez
turbulent forcing, S. Zhao,
N. Lardjane, I. Fedioun
! Quasi-spectral element method for
numerical integration of stiff
! LES/FDF of a lean premixed
unsteady combustion systems,
methane counterflow flame,
A. Koksharov, V. Bykov, U. Maas
M. Rieth, J.Y. Chen, F. Proch,
P. Lindstedt, A. Kempf
!Effects of preheat temperatures
and turbulence intensities on the
disruption of the reaction zone in
high Karlovitz premixed flames,
S. Lapointe, G. Blanquart
Org.: D. Markus, U. Maas,
D. Thévenin
! Large eddy simulation of a twostage liquid fueled swirl burner:
influence of injection strategies,
B. Cheneau, A. Vié, S. Ducruix
! On the influence of instabilities on
the direct blast initiation of twodimensional detonations, H.D. Ng,
C.B. Kiyanda, G.H. Morgan,
N. Nikiforakis
! Interactions of turbulence and
scalar structures in shear-driven
premixed turbulent flames using
DNS, H. Wang, E. Hawkes,
H. Kolla, J. Chen
!
! Numerical investigation on
detonation initiation and propagation
in supersonic reactive flows, J. Li,
Q. Xiao, W. Fan
! Detonation in a radial supersonic
outflow with simplified and realistic
chemistry, S. Korneev, A. Kasimov
! Numerical investigation on cellular
H2-O2-Ar detonation evolution in
mixtures with different hydrogen
concentrations, Q. Xiao, W. Fan,
H. Li, K. Wang, Q.Y. He
! Is is possible to achieve DDT
behind a continuously growing
Mach stem?, Y. Lv, M. Ihme
Chair: M. Ihme
! Two- and three-dimensional
numerical simulations of wildland
fires, A. Lamorlette, D. Morvan
! Evaluation of a sensor-driven
wildland fire spread modeling
strategy using the FireFlux
experiment, C. Zhang, M. Durand,
W. Tang, M. Goliner, A. Trouvé,
M. Rochoux, S. Ricci, B. Cuenot,
J.B. Filippi, C. Clements
! LES modelling of burning wildland
fuels, M. El Houssami,
A. Lamorlette, D. Morvan,
A. Simeoni
! How simulating the behaviour of
wildland fires?, D. Morvan
! Mathematical modelling of the
interaction between crosswind and
aviation-fuel fire engulfing a full
scale aircraft, G. Wang, H.Y. Wang
!CFD simulations of fire-induced
doorway flows in a small scale
enclosure, S. Suard, A. Koched,
H. Petrel, L. Audouin
Chair: B: Cuenot
Contributed presentations Contributed presentations
CP11 (3/3)
CP19
Detonation
Fires
! Extinction and reignition Dynamics
in turbulent dimethyl ether jet
flames, A. Bhagatwala, E. Hawkes,
P.T. Bremer, A. Gyulassy, J.Y. Chen
!Topology of turbulent premixed
flame interaction, R. Griffiths,
H. Kolla, W. Kollman, J. Chen,
S. Cant
Org.: S. Cant
Mini-symposium
MS13
Flame topology
! Combustor effusion cooling design
parameters analysis and modeling, ! Effective normal strain rate and
N. Savary, R. Hervé, G. Cottin
scalar gradient enhancement,
L. Cifuentes, C. Dopazo, J. Martin,
P.
Domingo, L. Vervisch, C. Jimenez
premixed flames flashback in
turbulent channel flows with fuel
stratification, A. Gruber, J.H. Chen
! Modelling chemistry in coupled
combustor and turbine CFD
simulations, R. Eggels
! Detailed analysis of light-round in
an annular multiple-injector
combustor, M. Philip, R. Vicquelin,
M. Boileau, T. Schmitt, S. Candel
!Numerical computation methods of
hot gases radiation in a turbofan
combustion chamber: performance
comparison for a design process,
R. Daviot, F. Loureiro
Chair: T. Poinsot
CP18
Gas turbine combustion
Mini-symposium
MS12 (2/2)
Safety related ignition
process
CP5 (6/6)
Chair: L. Vervisch
Session 2 (Cellier)
Wednesday April 22nd, 2015 16 Detailed program: Wednesday April 22nd, 2015 15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. Detailed program: Wednesday April 22nd, 2015 15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 17 18 Invited plenary lectures INVITED PLENARY LECTURES
PL1: Monday April 20th (8h30 – 9h30)
Simulation of turbulent flames: from high-performance computing
to low-order stochastic models for process control
Luc Vervisch
CORIA, CNRS and INSA de Rouen, France.
The objectives and challenges of turbulent combustion modeling are summarized in introduction, with an overview of
strategies and methods to simulate flames and practical burners. Then, most recent sub-grid scale modeling approaches
for Large Eddy Simulation (LES) of turbulent premixed and non-premixed flames are discussed and some applications
are presented. The time history of turbulent mixing and how it impacts on the requirements for sub-grid scale modeling is
specifically addressed with strategies to perform well-resolved and multi-physics simulations of industrial systems.
Finally, it is demonstrated how low-order stochastic models for process control, may be derived using results from LES.
Contact: [email protected]
PL2: Tuesday April 21st (8h30 – 9h30)
The hydrodynamic theory of premixed flames:
Laminar to turbulent propagation
Moshe Matalon
Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL. USA.
Significant advances in understanding the dynamics of premixed flames under laminar and turbulent conditions were
recently achieved using an asymptotic model that exploits the disparity between the length scales associated with the
fluid dynamic field, the diffusion processes and the highly temperature-sensitive reaction rates. In this hydrodynamic
model the flame, represented as a surface separating burned from unburned gas, propagates relative the fresh mixture at a
speed that depends on the local stretch rate modulated by a Markstein length that mimics the influences of diffusion and
chemical reaction occurring inside the flame zone. The propagation is therefore affected by the local mixture
composition and flow conditions and the flow field is modified, in turn, by the gas expansion resulting from the increase
in temperature caused by the heat released during combustion. The hydrodynamic model has been a valuable framework
for understanding flame-flow interactions under laminar conditions; the onset of flame instabilities and the nonlinear
development of flames subjected to the Darrieus-Landau instability; and, more recently, the structure and propagation
speed of turbulent flames. The present talk will focus on recent results within this context.
Because of the omnipresence of the Darrieus-Landau instability stemming from the gas expansion, laminar flames are
seldom flat. In sufficiently large domains, small cells developing on the surface of a planar flame tend to grow and merge
into larger cells that develop eventually into a single peak conformation with a pointed crest intruding into the burned gas
and wide rounded troughs towards the fresh mixture. These structures are stable and propagate steadily at a constant
speed significantly larger than the laminar flame speed. The bifurcation properties of planar flames, the nonlinear
development beyond the instability threshold and the structure and propagation speed of the stable cusped-like flames
have been well-established within the context of the hydrodynamic theory and validated by DNS. Turbulent flames have
similar characteristics. Flame brushes that are statistically planar, i.e., of zero mean curvature, can be only observed when
the Markstein number (scaled by the lateral size of the domain) exceeds a critical value. For Markstein numbers below
criticality, the turbulent flame brushes are much thicker, exhibit frequent sharp intrusions into the burned gas reminiscent
of the Darrieus-Landau instability, and remain partially resilient to the turbulence, at least at low intensities. The
influence of the Darrieus-Landau instability progressively decreases as the turbulence level increases with the flame
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. Invited plenary lectures 19 becoming increasingly controlled by the turbulence. Of greatest importance is the determination of the turbulent flame
speed and its dependence on turbulence intensity, which is shown to transition from a quadratic law at low intensities to a
sub-linear scaling at higher turbulence levels, in agreement with the experimental record. We show that the increase in
speed with increasing turbulence intensity is primarily due to the increase in the flame surface area as envisioned by the
pioneering work of Damköhler, while the leveling in the rate of increase of the turbulent flame speed with turbulence
intensity (the so-called bending effect) is partially due to frequent flame folding and detachment of pockets of unburned
gas from the main flame surface area, and partially due to flame stretching (for positive Markstein length). The proposed
scaling laws for the turbulent flame speed deduced from the simulations are free of any turbulence modeling assumptions
and/or adjustable parameters, and exhibit an explicit dependence on physically measurable quantities. These include flow
characteristics, such as turbulence intensity and integral scale and overall stretch rate (accounting for both flame front
curvature and hydrodynamic strain), and combustion characteristics, such as the effective Markstein length controlling
the fuel type, mixture composition and system pressure, and the thermal expansion coefficient determined by the ambient
state conditions and the total heat released.
PL3: Wednesday April 22nd (8h30 – 9h30)
Modeling and simulation of real-fluid thermodynamics
and transport in advanced combustion systems
Joseph C. Oefelein
Sandia National Laboratories, Combustion Research Facility, Livermore, CA, USA.
Real-fluid thermodynamics and transport are prevalent in a wide variety of advanced combustion systems
such as liquid rockets, Diesel engines, and gas turbines. For example, imaging has long shown that under
some high-pressure conditions, the presence of discrete two-phase flow processes becomes diminished. Under
such conditions, liquid injection processes transition from classical atomization and spray dynamics, to densefluid diffusion dominated mixing with no drops present. When and how this transition occurs, however, is not
completely understood. When it does, the classical view of liquid atomization and spray dynamics as an
appropriate model is questionable. Instead, non-ideal, real-fluid behavior must be taken into account using a
multicomponent formulation that applies to mixtures at high-pressure, supercritical conditions. This
presentation will focus on the progression of issues related to these high-pressure phenomena and treatment of
the extreme real-fluid, multicomponent, gas-liquid processes that occur as a consequence. First, a summary of
recent progress in understanding the processes responsible for the transition from spray dynamics to densefluid mixing will be presented to give perspective on the modeling challenges. The theoretical and numerical
treatment of these flows will then be analyzed within the formalism of Large Eddy Simulation (LES). Using
the filtered conservation equations as a foundation, closure issues using a model framework based on a
generalized treatment of the equation of state, thermodynamics, and transport processes will be described. The
related numerical issues in treating the extremely large gradients in thermo-physical properties that arise will
then be addressed. Throughout the presentation, representative results will be used to illustrate various aspects
of the problem, with emphasis on recent studies that focus on experiments of liquid hydrocarbon injection
processes being conducted in the high-pressure combustion vessel at Sandia National Laboratories. In the
latter, LES calculations reveal the structural characteristics of the inherent turbulent scalar mixing processes at
supercritical conditions directly relevant to advanced Diesel engines. The presentation will conclude with a
summary of key observations and suggestions for future research.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 20 MS1: Large eddy simulation: challenges and opportunities MINI-SYMPOSIA
MS1: Large eddy simulation: challenges and opportunities
V. Raman1 and M. Mueller2
1
2
University of Michigan, USA.
Princeton University, USA.
Large Eddy Simulation (LES) has become a vital part of combustion science, and has been the focus of computational
modeling for the past two decades. While the growth of computing aided its rise, significant theoretical and
computational challenges remain unaddressed. The goal of this mini-symposium is to invite discussion on these
challenges and future opportunities. Two sessions are planned. The first will have three senior researchers discuss their
perspectives on LES modeling. The second will have promising young researchers provide their vision for the future.
MS1 (1/2)
Monday April 20th (10h00 – 12h00)
Theoretical, numerical, and modeling issues in LES
V. Raman
Large eddy simulation (LES) has become the preeminent tool for simulating complex reacting flows.
Yet, several fundamental theoretical and numerical
challenges remain unresolved. In this talk, a summary
of the issues and emerging consensus on LES of
turbulent combustion is discussed. In particular, the
limitations of LES in terms of the range of applications
will be presented. This talk will set the stage for the two
sessions that provide insight from leading researchers in
this field.
contact: [email protected]
Using LES of ignition, quenching and instabilities to
design future gas turbines
T. Poinsot1, B. Cuenot2, L. Gicquel2, G. Staffelbach2,
A. Dauptain2 and F. Duchaine2
1
2
IMF Toulouse, CNRS, France.
CERFACS, France.
LES has replaced RANS in most laboratories and the
same evolution takes place now for companies. This
requires significant evolutions of LES codes to adapt to
the specificities of real combustion chambers:
multiphysics becomes an issue and LES codes have to
be coupled now to heat transfer codes to predict wall
temperatures, to soot and radiation models but also to
more precise inlet and outlet conditions to provide
realistic boundary conditions at inflow and outflow. The
interfaces between users and softwares also become a
difficulty. Even if parallel machines allow to perform
LES in reasonable human times, the CPU cost of LES
for companies is exploding, calling for drastic
reductions of costs for future LES through code
optimization but also mesh adaptation and smart
interfaces to minimize CPU waste. This talk will
discuss these issues in the specific case of gas turbine
engines.
Assessment of LES combustion models
H. Pitsch and P. Trisjono
Institute for Combustion Technology, RWTH Aachen University,
Germany.
Development and validation of combustion models for
large-eddy simulations is not straightforward. Often,
because of resolution requirements for the fluid flow,
combustion models are not really tested for the typical
laboratory flame validation cases. Furthermore,
uncertainties in specifying boundary condition make
validation difficult. On the other hand, DNS data can be
constructed in a way that circumvents these difficulties,
but because of restrictions in computational resources,
such data sets are even more removed from practical
combustion systems. In this talk, a joint validation
approach using experiments and DNS is proposed.
Systematic model development strategies will be
discussed.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. MS1: Large eddy simulation: challenges and opportunities 21 MS1 (2/2)
Data-driven modeling for LES
K. Duraisamy
Validation of multi-physics LES against sparse data
M. Mueller
As multi-physics LES models continue to become more
complex, validation of complete, integrated models
becomes an increasingly significant challenge. The
difficulty of the validation process is compounded by
the fact that experimental data is rarely available in a
single configuration to validate all components of a
complex model. In this talk, a pair of case studies is
discussed in utilizing novel error propagation and
uncertainty quantification algorithms to enhance the
model validation process for complex multi-physics
models with sparse experimental data.
University of Michigan, Ann Arbor, USA.
Opportunities for data-driven techniques to improve
predictive modeling of near-wall turbulence will be
discussed. High Reynolds number large eddy
simulations of turbulence require near-wall modeling, a
situation that is unlikely to change — at least not over
the next few decades. It is emphasized that neither DNS
nor experimental data exists in a form that is directly
useful to improve predictive models. Adjoint-driven
inverse problems are used to transform data into
information that is relevant to - and in the context of the model. This presentation will address the issue of
how to identify and formulate properly-posed datadriven problems and how machine learning techniques
can be effectively used to transform inferred
information into modeling knowledge.
The challenge of pollutant emission predictions
in realistic burners
Design optimization with LES
V. Moureau and G. Lartigue
CORIA, CNRS UMR6614, Normandie Université, France.
The aeronautical industry faces the challenge of
designing novel engines with better specific fuel
consumption while decreasing pollutant emissions such
as nitrogen oxide (NOx) and carbon monoxide (CO).
These pollutants have chemical time scales that are
different from those of the flame advancement and
require dedicatedlarge-eddy simulation models. This
presentation will focus on the prediction of NOx and
CO emissions in complex burners using tabulated and
finite-rate chemistry. This latter modeling approach is
very promising despite its high CPU cost but novel
strategies enable to benefit from many-cores supercomputers.
Q. Wang
MIT, USA.
How can large eddy simulation be used in the
engineering design process? How can they leverage
recent progress in extreme scale computing? We
identify key challenges specific to the engineering
design process, and some of the critical outstanding
problems and promising research directions.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 22 MS2: Combustion noise MS2: Combustion noise
F. Zhang1, H. Bockhorn1, C.O. Paschereit2, W. Schröder3 and J. Janicka4
1
Karlsruhe Institute of Technology, Germany.
TU Berlin, Germany.
3
RWTH Aachen, Germany.
4
TU Darmstadt, Germany
2
Unsteady combustion is regarded as the major source of noise generated by industrial combustion devices like gas
turbines. Therewith, a freely burning flame constitutes an acoustic monopole source due to the volumetric expansion of
the burning gases, which is related to the direct combustion noise. In case of confined systems, the combustion noise may
be augmented by indirect sources that arise during acceleration of unevenly heated gases through the system exhaust.
The indirect combustion noise is manifested as an acoustic dipole source involving interactions between temperature
inhomogenities and mean flow variation. This mini-symposium presents experiments and different numerical studies
using LES/DNS/CAA methods to analyse both direct and indirect combustion noise generated by turbulent premixed
flames.
Direct combustion noise of premixed flames:
experiments and simulation using compressible
LES and DNS
F. Zhang1, H. Nawroth2, P. Habisreuther1, J. Moeck2,
C. Paschereit2 and H. Bockhorn1
1
2
KIT Karlsruhe, Germany.
TU Berlin, Germany.
The direct combustion noise generated by an
unconfined, premixed flame operated by a generic
burner has been experimentally and numerically
investigated. Comparison of the sound pressure levels
(SPL) obtained from the microphone measurements and
the direct numerical simulation (DNS) shows a very
good agreement, whereas it is slightly underestimated
by the large eddy simulation (LES). With help of the
DNS, the strong correlation between the OH*
concentration and the heat release rate have been
proven. In addition, the joint probability density
function (PDF) of the heat release rate and OH* mass
fraction has been derived to give quantitative findings
of both parameters.
A hybrid approach to predict combustion noise of
premixed flames
A. Hosseinzadeh1, G. Geiser2, J. Janicka1 and
W. Schröder2
1
2
TU Darmstadt, Germany.
In the current work a hybrid approach (LES/CAA) is
proposed to analyze the combustion noise of premixed
flames. The low-Mach combustion LES uses the
artificially thickened flame approach coupled with
FGM tabulated chemistry. The CAA uses acoustic
perturbation equations (APE). Diverse configurations of
a generic premixed burner are numerically investigated
using the proposed hybrid approach. The predicted
sound pressure levels (SPL) using the hybrid approach
and the measurements are in a very good agreement.
Besides direct combustion noise mechanisms induced
by heat release fluctuations, indirect mechanisms by
acceleration of entropy inhomogeneities and nonisentropic mixing processes are also found to be the
major noise sources.
LES based simulations of combustion noise in a
helicopter engine
T. Livebardon1, L. Gicquel1, T. Poinsot2 and E. Bouty3
1
CERFACS, France.
Institut de Mécanique des Fluides de Toulouse, France.
3
Turbomeca S.A., France.
2
Reducing helicopter noise disturbances has become a
major issue because of the growth of air traffic at the
vicinity of populated areas and ACARE 2020
objectives. At low and medium frequencies, helicopter
engines are known to be major contributors in the
radiated noise, especially during take-off. Indeed, an
emitted broadband noise at the exhaust, called corenoise, is composed of turbomachinery and combustion
noise in the absence of jet noise. In this scope, a method
to predict combustion noise in real aero-engines using
large eddy simulations of the combustion chamber
coupled with an analytical approach to model the
acoustic transmission of acoustic and entropy noise
through the turbine stages is described. The proposed
strategy is tested by comparing predictions of the
computed noise with experimental results obtained for a
full helicopter engine with pressure sensors located in
the chamber and in all turbine stages. The waves
leaving the combustion chamber are extracted from
these simulations at the outlet of the chamber, and an
analytical method based on actuator disk theory gives
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. MS2: Combustion Noise 23 noise levels at the various turbine stages using the
waves amplitudes at the chamber outlet. LES of the
combustion chamber for two representative operating
points are achieved and discussed.
Estimating indirect combustion noise in nozzle flows
with a 2D analytical model
J. Zheng1, M. Huet1, A. Giauque2, F. Cléro1 and
S. Ducruix3
1
2
3
ONERA, France.
Laboratoire de Mécanique des Fluides et d’Acoustique, France.
Laboratoire EM2C, CNRS and Ecole Centrale Paris, France.
combustion noise use quasi-1D flow assumptions. A
new 2D model estimating indirect combustion noise
generated by the acceleration of non-uniform
temperature regions through a subcritical nozzle is
presented. This model extends the 1D models proposed
by Giauque et al. (JEGTP, 2012) and Duran and
Moreau (JFM, 2013) by taking into account the
deformation of the fluctuating entropy fronts. An
original approach is proposed that treats the acoustic
fluctuations as 1D along the nozzle while entropy
fluctuations are modeled as 2D with longitudinal and
radial dependencies.
To achieve reduced computational times, most of the
semi-analytical methods for the estimation of
MS3: Advances in linear-eddy and one-dimensional-turbulence modeling
H. Schmidt
BTU Cottbus-Senftenberg, Germany.
DNS is currently the numerical tool to investigate fundamental problems in combustion, since it solves the governing
physical conservation equations without assumptions. Unfortunately due to the range of spatial and temporal scales
emerging in reactive flows currently it is limited to mostly fundamental research. Interesting alternatives are stochastic
approaches like the linear-eddy model (LEM) and the one-dimensional-turbulence (ODT) model and multi-dimensional
Eulerian and Lagrangian approaches that incorporate them. LEM and ODT resolve molecular effects (as DNS) on small
scales, but use a one-dimensional map-based stochastic process compatible with conservation laws to reduce the degrees
of freedom. The models have been successfully applied to many flows and are under continuous development and
extension. During the minisymposium we present (i) counterflow flames results, including comparison to DNS, (ii) a
new LEM-based regime- independent modeling concept, (iii) ODT results on the auto-ignition of ethylene/air flames,
and (iv) a 3D extension of LEM.
The representative interactive linear-eddy model
(RILEM) for regime-independent turbulent nonpremixed combustion modeling
On the benefits of using LEM- and ODT-based
approaches in numerical combustion
H. Schmidt
T. Lackmann1, A. Kerstein2 and M. Oevermann1
BTU Cottbus-Senftenberg, Germany.
1
We summarize the progress in analyzing, applying, and
improving stochastic turbulence models in reactive fluid
mechanics that are based on either the linear-eddy
model (LEM) or on one-dimensional turbulence (ODT).
Compared to direct numerical simulation (DNS), these
models span a wider range of scales. Compared to
Reynolds averaged Navier Stokes (RANS) and large
eddy simulation (LES), (i) the molecular effects are
retained and (ii) no assumption of scale separation is
made. After a general overview we will show and
discuss recent results on counterflow flames and
compare them to DNS.
2
Chalmers University of Technology, Sweden.
Consultant, USA.
Future engines with efficient and environmentally
friendly combustion of fuel are likely to operate under
low temperature combustion (LTC) conditions.
However, most combustion models used in todays CFD
codes are based on the assumptions of a specific
combustion mode and regime. Their predictive
capabilities might be limited under LTC. Here we
present a new regime independent modeling concept for
non-premixed turbulent combustion based on the lineareddy model. The model in its current development state
features a single linear-eddy line representative of the
combustion process. Local coupling with the flow is
achieved via a presumed PDF for the mixture fraction.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 24 MS3: Advances in linear-‐eddy and one-‐dimensional-‐turbulence modeling Comparison between ODT and DNS for ethylene/air
auto-ignition
Introduction of unsteadiness and small-scale
resolution into steady-state reacting-flow solvers
using LEM3D
A. Abdelsamie and D. Thévenin
S. Sannan1 and A. Kerstein2
University of Magdeburg, Germany.
1
The auto-ignition of a turbulent ethylene/air mixture is a
very complex physical process. Resolving
all
turbulence and flame scales in a DNS leads to
extremely expensive computations. Therefore, ODT
would be - if suitable - an excellent alternative.
Qualitative and quantitative comparisons between ODT
and DNS are conducted concerning ethylene/air autoignition in this work. First result shows that ODT is
able to predict correctly auto-ignition or misfire of an
atmospheric, stoichiometric mixture in a temperature
range of [1000-1400] K. If this observation can be
generalized, the probability of auto-ignition could be
efficiently deduced from ODT simulations.
2
SINTEF Energy Research, Norway.
Consultant, USA.
A 3D subgrid closure approach, LEM3D, has been
developed. The approach is based on the Linear Eddy
Model (LEM), and structurally involves three
orthogonally intersecting arrays of LEM domains that
are coupled so as to capture the 3D character of fluid
trajectories. LEM3D thus provides small-scale
resolution in all three spatial directions of the flow field.
The conceptual basis for LEM3D is presented, together
with model performance evaluation for multi-stream
mixing and differential diffusion in turbulent round jets.
Progress toward implementation of two-way coupling
between LEM3D and RANS for combustion
applications is described.
MS4: Uncertainty quantification in computational combustion
H. Nahjm1, M. Frenklach2 and A. Tomlin3
1
2
3
Sandia National Laboratories, USA.
University of California at Berkeley, USA.
University of Leeds, UK.
Predictive combustion computations rely on calibrated and validated models. These models rely on parameters that are
estimated either from experimental measurements or from theory/computations, and are, to some extent, uncertain.
Accordingly, it is important that computational predictions based on these models explore the impact of input
uncertainties, and provide reliable quantification of uncertainties in their predictions.
This minisymposium focuses on challenges and recent advances in uncertainty quantification (UQ) in chemical models
and combustion computations. It brings together experts from a wide range of backgrounds working in computational
combustion and interested in UQ, parameter estimation, and model assessment.
MS4 (1/4)
th
Monday April 20 (13h30 – 15h30)
Combining theory and experiment to reduce
uncertainties in the derivation of phenomenological
rate coefficients for combustion systems
A. Tomlin, R. Shannon, P. Seakins, M. Pilling, M. Blitz
and S. Robertson
Statistical rate theory calculations, in particular
formulations of the chemical master equation (ME), are
widely used in order to calculate rate coefficients that
are used within kinetic mechanisms describing the
combustion of many different fuels. Such calculations
can be applied over wide ranges of temperatures and
pressures and hence in this sense are more general than
individual experimental kinetic studies. However
despite the increasing accuracy of ab initio data, small
uncertainties in the input parameters for ME
calculations can lead to relatively large uncertainties in
the calculated rate coefficients. ME input parameters
may be constrained further using experimental data
over more limited temperature and pressure conditions.
The relationship between experiment and theory will be
discussed in this paper, and in particular, whether
experiments performed at lower temperatures and
pressures can help to constrain reaction rates at
combustion relevant conditions.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. MS4: Uncertainty quantification in computational combustion Uncertainties in theoretically predicted elementary
rate coefficients
S. Klippenstein
Argonne National Laboratory, USA.
A survey will be provided of the uncertainty in various
components of ab initio transition state theory master
equation based theoretical predictions for thermal rate
constants. Uncertainties in the electronic energies, the
vibrational frequencies, anharmonicity treatments,
tunneling estimates, and energy transfer parameters will
each be discussed at length. The role of variational
optimizations will also be discussed. A number of
sample studies covering a range of reaction types will
be used as illustrations.
previous estimates. C2H3 + O2 will be predominantly
chain branching above 1700 K. Uncertainty analysis is
presented for the two most important transition states.
The uncertainties in these two barrier heights result in a
significant uncertainty in the temperature at which
CH2CHO + O overtakes all other product channels.
Compared to previous mechanisms, the present work is
expected to accelerate fuel consumption in combustion
models. The impact of these mechanistic changes on
combustion properties will be presented.
Correlated uncertainty quantification: application to
complex chemical kinetics mechanisms
J. Sutton1, W. Guo1, M. Katsoulakis2 and D. Vlachos1
1
2
Probabilistic Inference of reaction rate parameters
based on summary statistics
M. Khalil and H. Najm
We present the results of an application of Maximum
Entropy and Approximate Bayesian Computation
methods to the estimation of the joint probability
density on the Arrhenius parameters of the H + O2 =>
OH + O reaction. Available published results in the
form of summary statistics, being nominal values and
error bars of the rate coefficient at a number of
temperatures, are used to generate consistent OH
concentration profiles, and associated joint posterior
densities on the Arrhenius parameters, using a nested
Markov Chain Monte Carlo procedure. A consensus
joint posterior on the parameters is obtained by pooling
the aforementioned densities.
University of Delaware, USA.
University of Massachusetts, USA.
We demonstrate that surface kinetics and in general
reaction mechanisms have certain correlations. To
address this problem, we formulate a correlated
parameter sensitivity analysis method and apply to
catalytic kinetics. We then perform a number of density
functional theory calculations (DFT) and estimate the
posterior by using Bayesian statistics and by injecting
the DFT data into a prior. We show that uncertainty is
significant for surface kinetics and can rationalize most
but not all of the deviations from experimental data.
MS4 (2/4)
Comparison of probabilistic and deterministic
frameworks of uncertainty quantification
Uncertainty quantification in the oxidation
of vinyl radical
25 M. Frenklach1, A. Packard1, J. Sacks2, R. Pablo3 and
G. Garcia-Donato4
1
National Institute of Statistical Sciences, USA.
ISEG Technical University of Lisbon, Portugal.
4
Universidad de Castilla-La Mancha, Spain.
2
F. Goldsmith
Brown University, USA.
State-of-the-art calculations of the C2H3O2 potential
energy surface are presented. A new method is
described for computing the interaction potential for R
+ O2 reactions. The method, which combines accurate
determination of the potential on the quartet surface
with multi-reference calculations of the doublet/quartet
splitting, decreases the uncertainty in the potential and
thence the rate constants by more than a factor of two.
The temperature and pressure dependent rate
coefficients are computed using variable reaction
coordinate transition state theory, variational transition
state theory, and conventional transition state theory, as
implemented in a new RRKM/ME code. The product
distributions are considerably more complex than
3
Numerical modeling of physical phenomena must
accommodate sources of uncertainty rooted in the
formulation of underlying physical models, their
mathematical realization and numerical implementation,
accounting for uncertain model parameters and
experimental calibration data. How to use the
experimental data and the numerical realization to
enable prediction of new settings and estimate
unknowns has had wide attention in recent years. Even
when a physical model and its numerical realization is
an accurate representation of the phenomenon, methods
and capacity to utilize experimental data for calibration
and prediction is not yet standardized. Such a setting is
found, for instance, in combustion chemistry where the
physical model is a complex network of many chemical
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 26 MS4: Uncertainty quantification in computational combustion species related through hundreds and thousands of
chemical reactions involving many uncertain model
parameters. Moreover, the limited experimental data are
heterogeneous
with
sketchy
assessments
of
measurement error. Here we compare a deterministic
approach to the problem, namely the Bound-to-Bound
Data Collaboration, with a Bayesian approach that
embeds the analysis into a probabilistic framework. The
comparison is performed using methane combustion as
an illustrative example. Our findings show that, in
general, the predictions obtained match but, in terms of
estimation of unknown parameters, subtle differences
arise that add insights about limitations of each of the
methodologies.
data, consisting of ignition measurements in shock
tubes and rapid compression machines, and flame
velocity measurements covering wide ranges of
temperature, pressure, equivalence ratio and H2/CO
ratio. Arrhenius parameters A, n, and E of 18
elementary reaction steps were optimized, and also 9
third body collision efficiency coefficients of four
pressure dependent reactions. The joint covariance
matrix of the optimized parameters was calculated,
which characterizes the temperature dependent
uncertainty of the optimized reactions rate coefficients
and also their correlation. The obtained posterior
uncertainties were compared with the prior
uncertainties, determined on the basis of literature
sources for the important rate parameters.
Combining theoretical and experimental data in
uncertainty quantification across multiple scales
M. Burke
Columbia University, USA.
Recent developments in and results from a multi-scale
informatics approach to kinetic model uncertainty
quantification will be discussed.
The approach
simultaneously integrates information from a wide
variety of sources and scales: ab initio electronic
structure calculations of molecular properties, rate
measurements of isolated reactions, and global
measurements of multi-reaction systems. The resulting
model representation consists of a set of theoretical
kinetics parameters (with constrained uncertainties) that
are related through elementary kinetics models to rate
constants (with propagated uncertainties) that in turn
are related through physical models to global behavior
(with propagated uncertainties).
Comparisons of multi-scale informed model predictions
and recent data will be shown that reveal a high level of
predictive accuracy for both small and large scales
(molecular properties and global observables).
Additionally, the utility of the approach for design of
both experiments and theoretical calculations, in a
manner accounting for existing theoretical and
experimental data as well as accounting for relevant
parametric and structural uncertainties in interpreting
potential new data, will be demonstrated.
Uncertainty quantification of the rate parameters of
the syngas combustion system
T. Varga1, C. Olm1, I. Zsély1, T. Nagy2, É. Valkó1,
R. Pálvölgyi1, H. Curran3 and T. Turányi1
1
Institute of Chemistry, Eötvös University (ELTE), Hungary.
MTA Research Centre for Natural Sciences, Hungary.
3
Combustion Chemistry Centre, NUI Galway, Ireland.
2
Statistical calibration of simplified chemical
mechanisms for Diesel engine combustion
L. Hakim, G. Lacaze, M. Khalil, H. Najm and J.
Oefelein
In this work, a reduced chemical mechanism for large
eddy simulation (LES) is proposed to predict autoignition and flame propagation in Diesel engines, two
features that directly influence efficiency, reliability and
emissions. The mechanism is calibrated using Bayesian
inference, providing optimal parameter estimates and
respective uncertainties. The latter can then be
propagated through the LES to quantify the
uncertainties in the simulations. As an example, the
technique is applied to the Engine Combustion Network
(www.sandia.gov/ECN) Spray-A case where a twostage auto-ignition of n-dodecane in air has been
observed.
Bayesian inference of chemical kinetic models from
proposed reactions
N. Galagali and Y. Marzouk
Massachusetts Institute of Technology, USA.
We present a new framework for tractable Bayesian
inference of chemical kinetic models in case of a large
number of model hypotheses generated from a set of
proposed reactions. The approach involves imposing
point-mass mixture priors over rate constants and
exploring the resulting posterior distribution using an
adaptive Markov chain Monte Carlo method. We show
that further gains in sampling efficiency can be realized
by analyzing the chemical network structure in order to
reduce the space of MCMC exploration.
An optimized syngas combustion mechanism has been
developed using a large set of indirect experimental
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. MS4: Uncertainty quantification in computational combustion Region of influence-based sensitivity analysis in
turbulent combustion
V. Carey and R. Moser
University of Texas at Austin, USA.
Adjoint-based sensitivity analysis is a powerful tool for
UQ in many-parameter systems. Time-dependent
turbulent systems present several obstacles for this
methodology, including solution storage, analytic
jacobians, and adjoint blowup over long time. We
address these challenges when applied to turbulent
combustion with a combination of checkpointing,
automatic differentiation software, and space-time
domain reduction to a "Region of Influence" for
combustion-relevant quantities of interest.
MS4 (3/4)
Tuesday April 21st (13h30 – 15h30)
Handling model error in the calibration
of physical models
H. Najm1, K. Sargsyan1 and R. Ghanem2
1
2
University of Southern California, USA.
We present a statistical model calibration strategy that
focuses on model error, and is tailored for physical
models. We require that the mean prediction is centred
on the data, and that the predictive uncertainty is
consistent with the range of discrepancy between the
means of the prediction and the data. We embed
statistical model error terms in select model
components. We then formulate the problem as a
density estimation problem and solve it using
approximate Bayesian computation methods.
We
demonstrate this construction for calibration of a global
chemical model for methane-air against a detailed
kinetic mechanism in an ignition problem.
Facilitating uncertainty quantification for large,
detailed reaction mechanisms
R. West1, S. Goldsborough2 and A. Fridlyand1
1
2
Northeastern University, USA.
Large, detailed reaction mechanisms describe the
ignition and combustion behavior of real,
transportation-relevant fuels like gasoline and diesel,
represented by surrogate blends, e.g., n-heptane/isooctane/toluene. We describe an approach to quantify the
uncertainty for such mechanisms at realistic combustion
conditions, where global sensitivity analysis can be
employed. Realistic uncertainty bounds are applied for
27 each reaction, with the base chemistry, i.e., C0-C3,
treated in detail and fuel-specific reactions treated by
reaction class or family.
Automated means are
developed to generate the UF file for an existing
mechanism, by first identifying the reacting species,
then categorizing the reactions.
Combustion properties of H2/CO mixtures:
consistent chemical mechanism from collaborative
data processing
N. Slavinskaia, U. Riedel and J. Starcke
DLR, Germany.
The revision of the state of the H2/CO DLR kinetic
mechanism and related experimental data has been
performed. This revision was performed on the base of
numerical algorithms and tools developed in the
DataCollaboration module of the automated datacentric infrastructure, Process Informatics Model
(PrIMe). The uncertainty-quantification framework of
Data Collaboration can establish consistency or
inconsistency of a data-and-model system, when the
kinetic parameters of a reaction mechanism and
experimental observations used for model validation are
known within its uncertainties. On this way for the
studied H2/CO DLR kinetic mechanism, the influence
of parameter and experiment uncertainties on the
optimal solution have been examined, and experimental
targets that are most difficult to match as well as model
parameter values that are likely to be questionable have
been identified. The 100 selected experimental
observations (targets) for ignition delays and laminar
flame speeds of H2/CO systems with boundary
uncertainties for measured observations followed from
references were included in the Data Set of
DataCollaboration
module.
Performed
analysis
enhanced the quality of experimental data adopted for a
model parameter optimization over the feasible region
of the parameter space. Adding experimental
uncertainties to parameter uncertainties the rate
coefficients of the 12 most important reactions have
been then optimized. The applied new approach to
optimizing combustion models by constraining the
optimization not only to parameter uncertainties but
also to the uncertainties in experimental data assures the
best-fit solution. The predictions, calculated with so
obtained model, deviate the least from the experimental
targets while remaining within their experimental
uncertainties. The applied methods allow producing the
best-fit solution predictive model with evaluated
uncertainty level.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 28 MS4: Uncertainty quantification in computational combustion Effect of uncertainties in detailed chemistry on
combustion model parameters
N. Dumont, R. Vicquelin and O. Gicquel
Parameters such as auto-ignition delay, laminar flame
speed, quenching strain rate and so on are extensively
used in turbulent combustion models. Their evaluations
rely on numerical simulations using detailed chemistry
mechanisms in canonical flame configurations:
Homogeneous reactors, premixed and non-premixed
flamelets. However, these model constants are uncertain
because of the inherent uncertainty in the kinetic
parameters of detailed mechanisms. In this study, the
uncertainties in these quantities of interest are evaluated
with a Monte-Carlo method due to the high number of
uncertain parameters in detailed mechanism. This is
done for several types of fuel (hydrogen, methane and
heavier hydrocarbon fuels) in different flame
configurations in a high-performance computing
framework. Several operating conditions are
investigated to identify the most sensitive conditions.
Adjoint-based sensitivity for understanding
chemistry modeling
V. Raman1, K. Braman2 and T. Oliver2
1
2
University of Texas at Austin, USA.
Chemistry models are calibrated mainly using zero or
one dimensional flame experiments. In this work,
adjoint-based sensitivity is used as the basis for
evaluating multi-dimensional flames with the goal of
calibrating and understanding model performance.
Continuous adjoint equations are derived for low-Mach
number flows, and applied to laminar and turbulent
flame simulations. It is shown that adjoints provide a
unique measure for determining the adequacy of
chemistry models through a metric named field
sensitivity
MS4 (4/4)
Needs and progress in assessing the accuracy of LES
J. Oefelein and G. Lacaze
complicated by the interdependence of different subfilter models, competition between model and
numerical errors, model variability, and numerical
implementation. This presentation will provide an
overview of needs and progress to date in the
development of predictive LES and application of UQ
as a tool to validate its accuracy.
Uncertainty quantification of rate rules for normal
alkanes using Bayesian analysis
L. Cai1, L. Kröger1, V. Raman2 and H. Pitsch1
1
2
RWTH Aachen University, Germany.
Universitiy of Michigan, Ann Arbor, USA.
The uncertainties of the rate rules for the mechanism of
C5-C12 normal alkanes, expressed as probability
densities, are estimated using the stochastic Bayesian
approach. Sampling from these estimated probability
densities, the uncertainties of the model prediction for
global combustion targets can be determined. Joint
probability densities of rate rules and model responses
are evaluated to reveal the effect of various rate rules on
fuel reaction pathways and on combustion targets. The
results are also compared to those determined by the
uncertainty quantification method based on the
conventional optimization technique with polynomial
chaos expansions.
Optimal experimental design of furan shock tube
kinetic experiments
D. Kim, F. Bisetti, Q. Long, R. Tempone, A. Farooq
and O. Knio
KAUST, Saudi Arabia.
A Bayesian optimal experimental design methodology
has been developed and applied to refine the rate
coefficients of elementary reactions in Furan
combustion. We focus on the Arrhenius rates of Furan +
OH = Furyl-2 + H2O, and Furan + OH = Furyl-3 +
H2O, and rely on the OH consumption rate as
experimental observable.
A polynomial chaos
surrogate is first constructed using an adaptive pseudospectral projection algorithm. The PC surrogate is then
exploited in conjunction with a fast estimation of the
expected information gain in order to determine the
optimal design in the space of initial temperatures and
OH concentrations.
The Large Eddy Simulation (LES) technique is widely
viewed as an engineering tool of the future that is
conceptually capable of representing a wide variety of
turbulent reacting flow processes. The potential
benefits, however, are shadowed by the fact that LES is
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. MS4: Uncertainty quantification in computational combustion Industrial & applied V/UQ for a 15MW
coal-fired boiler
P. Smith and S. Smith
The University of Utah, USA.
Computational and experimental results from industrial
combustion applications are expensive to obtain, sparse
in number and high in uncertainty. However, there is
high value in extracting as much information as
possible from the combined set of experimental and
computational data. This study targeted a validation
with uncertainty quantification using LES simulations
29 of a 15MW ox-coal power boiler operated by Alstom
Power and using 50 different measurements of the heat
flux, temperature and O2 concentration as the specific
quantities of interest as a function of wall thermal
conductivity, fuel feed rate, and coal reactivity. Our
validation approach identified the region of
simultaneous consistency between experimental and
simulation data, according to a consistency constraint,
where the defect between the quantity of interest as
predicted by the model and as measured by the
experiment is bounded by the measurement uncertainty.
MS5: Numerical methods for compressible combustion
F. di Mare
TU Darmstadt / DLR, Germany.
The solution methods for the simulation of combustion system developed in the last decades have relied on the
assumption that the reacting mixtures behaved ideally and that dynamic effects were largely negligible (low-Mach
approximation). However, as the integrated modelling and simulation of propulsion systems in their entirety will
become necessary for their global design and optimisation, novel, comprehensive solution methods accounting for
complex thermodynamic effects must be developed. The contributions presented during this mini-symposium will
describe advances in efficient solution approaches for fully-compressible solvers where non-ideal effects are taken in
consideration as well as compressibility effects in complex combustion phenomena, such as flashback and thermoacoustic instabilities.
An implicit, density-based algorithm for coupled
simulations of arbitrary gas mixtures
F. di Mare1 and L. di Mare2
1
2
TU-Darmstadt/DLR, Germany.
Imperial College London, UK.
The development of new design concepts for cleaner
and efficient propulsion and energy transformation
devices (gas turbines, combined gas-steam generation
groups) requires the global optimization of all machine
components. In the present work a novel numerical
approach is illustrated, which allows to model
accurately and efficiently departures from an ideal
behaviour of the working fluid in density-based
solvers. The concept of residual internal energy permits
a ready extension of classic flux-difference splitting or
flux-splitting solution algorithms to (reacting) mixtures
of thermally and calorically imperfect gases of variable
composition. A fully implicit formulation is then
derived in terms of mass fractions.
Simulation of high-pressure turbulent mixing and
reacting real gas flows
M. Pfitzner and H. Müller
Bundeswehr University Munich, Germany.
Many technically relevant combustion systems operate
at elevated pressures, where the use of real gas
equations of state might be important to accurately
simulate the turbulent mixing and combustion
phenomena. Examples are rocket combustors, gas
turbine combustors and the combustion in diesel
engines. In the presentation, we will show how to use
pressure correction numerical schemes to simulate lowMach number flows without and with combustion. The
method is implemented in OpenFOAM (RANS and
LES). The resulting real gas CFD code using modern
cubic equations of state is validated with high pressure
mixing and combusting flows.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 30 MS5: Numerical methods for compressible combustion Effect of compressibility in the flashback of
premixed flames in confined channels
Compressible combustion and nonlinear dynamics
for thermoacoustic analysis
M. Hassanaly, H. Koo and V. Raman
C. Lee and S. Cant
The University of Michigan, USA.
University of Cambridge, UK.
Predictive models that could capture the onset and the
propagation of a flashback event would be
indispensable for high-hydrogen content gas turbines
combustors. In this work, we use large eddy simulation
(LES) for describing the boundary layer flashback. A
low-Mach number assumption has been previously used
to study the accuracy of LES chemistry models.
However, Direct Numerical Simulations (DNS) have
shown that the flame interface was also inducing a steep
pressure gradient, whose impact was neglected with the
low-Mach number assumption. The purpose of this
work is to describe and quantify the role of
compressibility on the flashback propagation.
Acoustically-coupled combustion instabilities are
difficult to predict and hard to eradicate in practical
systems. Many of the existing design tools are based on
assumptions of low Mach numbers and linear
perturbations. In the present work, a more general
approach has been developed using fully-compressible
CFD and a set of nonlinear analysis methods. The
approach is described, and results are presented for the
classic Volvo afterburner test case, for which
experimental data is available. Comparisons between
the present results and the experimental data serve to
validate the approach, and conclusions are drawn
regarding the mechanisms behind the observed
combustion instabilities.
MS6: Towards exascale simulation of turbulent combustion
J. Chen1 and R. Sankaran2
1
2
Oak Ridge National Laboratory, USA.
Exascale computing will enable combustion simulations in parameter regimes relevant to next-generation combustors
burning alternative fuels. High-fidelity simulations are needed to provide the underlying science base required to
develop vastly more accurate predictive combustion models used ultimately to design fuel efficient, clean burning
vehicles, planes, and power plants for electricity generation. However, making the transition to exascale poses a number
of algorithmic, software and technological challenges. As Moore’s Law and Dennard scaling come to an end exascale
computing will be achieved only through massive concurrency. Addressing issues of data movement, power
consumption, memory capacity, interconnection bandwidth, programmability, and scaling are critical to its success. In
this minisymposium numerical algorithms, programming models and domain specific languages needed to support high
fidelity numerical simulations of turbulent combustion are presented.
MS6 (1/2)
Legion as a programming model for combustion
simulation at the exascale
J. Chen1, M. Bauer2, S. Treichler2, A. Aiken2 and
A. Bhagatwala1
1
2
Stanford University, USA.
Legion is a programming model designed for exascale
machines with a number of features designed for
heterogeneous, hierarchical machines that are expected
at the exascale. Specifically, Legion supports
hierarchical decomposition of both tasks and data to
match the structure of the machine and provides a
deferred execution model for hiding long and variable
latencies inherent in large, distributed memory
architectures. Legion is designed to provide a level of
abstraction above the concrete hardware with an explicit
mapping from the computation to a specific machine.
Mapping is done dynamically, and so decisions about
where tasks will run and where data will be placed can
take advantage of runtime information. Legion
promotes code portability as porting to a new machine
involves changing only the mapping tuned for the new
machine. Lessons learned from a recent port of a
petascale DNS combustion code, S3D, to Legion on
Titan at ORNL will be discussed.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. MS6: Towards exascale simulation of turbulent combustion Toward large-eddy simulation of complex burners
with exascale super-computers: a few challenges
and solutions
V. Moureau
31 focus on accelerators, massively many core and highly
vectorised architectures and programming models along
with a few recent examples.
CORIA, CNRS & INSA de Rouen, France.
Large-Eddy Simulation (LES) is a powerful approach
for the simulation of complex burners as it resolves the
most energetic scales of turbulence and their
interactions with the reactive fronts. However, LES is
very CPU intensive as it requires fine meshes and long
accumulation times. Future exascale machines present a
number of challenges for combustion LES, which need
to be addressed: i) efficient solving of the low-Mach
number Navier-Stokes equations on a large number of
cores, ii) load balancing of the stiff integration of the
chemical source terms arising in operator splitting
approaches, iii) data mining of billion cells LES.
Combustion simulation on next-generation
architectures
J. Bell
Lawrence Berkeley Laboratory, USA.
Computer architectures are shifting to many-core,
possibly heterogeneous nodes with reduced memory per
core. Block-structure adaptive mesh refinement (AMR)
is well-suited to this type of architecture. AMR reduces
the number of degrees of freedom needed to represent
the solution and provides a hierarchical model for
computation ideally suited to many-core systems.
However, developing AMR methodology for next
generation architectures raises a number of challenges
related to the increased importance of data movement
and load balancing. In this talk, we discuss some of
these issues in the context of both compressible and low
Mach number formulations.
Legacy codes and the jump to exascale : fluid
dynamics simulation with AVBP and HPC
G. Staffelbach1, O. Vermorel1, S. Jaure1, C. Fournier1,
I. D'Ast1 and E. Oseret2
1
2
CERFACS, France.
Exascale Computing Research, France.
Combustion is one of the fields where HPC is the most
needed. Leadership class systems enable large advances
for research on more reliable and pollution compliant
systems using unsteady combustion simulations.
Adapting current programs to benefit from the everchanging improvements of architecture is the key to a
sustainable effort. This talk will present recent
developments for the AVBP code used for LES of
combustion in gas turbines, engines and rockets. It will
Direct numerical simulation of low Mach number
combustion beyond petascale
C. Frouzakis1, A. Tomboulides2, S. Kerkemeier1 and
P. Fischer3
1
2
3
ETH Zurich, Switzerland.
University of Western Macedonia, Greece.
The extension of the open source incompressible flow
solver Nek5000 for the direct numerical simulations of
low Mach number combustion employs the spectral
element method (SEM) for spatial discretization, where
the solution is approximated by tensor product
polynomials of order N (typically 8-12) on each of E
elements. In combination with implicit or semi-implicit
temporal discretization schemes, small dispersion errors
can be efficiently obtained in complex geometries at a
cost per gridpoint that is comparable to low-order
methods.
The analysis of the performance and
scalability of the domain decomposition approaches
indicate that the solver can perform well at exascale for
a granularity of one element per (current-day) core.
Recent applications and current development efforts
will be presented.
Physical and algorithmic approaches to numerical
combustion at the exascale
S. Cant
Cambridge University, UK.
Exascale computing offers great opportunities and also
some potentially serious challenges. The fundamental
physical scaling laws for turbulent combustion ensure
that there is continuing demand for ever-greater
computational resources. On the other hand, it is not
obvious that currently-successful explicit algorithms
will continue to scale well on hardware involving
millions of compute cores, possibly equipped with
numerical co-processors and with increasingly nonuniform access to distributed memory. The present
work explores the options for progress in spatial
discretisation methods and time stepping schemes, with
emphasis on examples from turbulent premixed
combustion, as well as two-phase flow and spray
combustion.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 32 MS6: Towards exascale simulation of turbulent combustion MS6 (2/2)
st
Tuesday April 21 (10h00 – 12h00)
Reacting flow simulation framework for
heterogeneous and many-core architectures
R. Sankaran1, B. Lee2 and H. Im2
1
2
ORNL, USA.
With the advent of exascale computing, the computer
architectures are expected to shift more heavily towards
accelerators and many-core processors. These new
architectures require legacy simulation codes to be
rewritten and engineered to take full advantage of the
hardware. This talk describes a new reacting flow
simulation framework that is being developed to
transition to heterogeneous architectures. The multiphysics models and kernels required for combustion
simulations are expressed as function objects that are
executed on the target processors using parallel
frameworks such as Kokkos. Performance results on
GPU and MIC accelerators are compared for
representative benchmark problems.
Efficient abstractions for exascale software design
J. Sutherland
University of Utah, USA.
Exascale computing will require software abstractions
that expose and exploit hierarchical parallelism while
maintaining programmability. This is particularly
challenging given the complexity of the physics models
that we seek to deploy on exascale systems as well as
uncertainty in what future computer architectures will
be. This talk explores strategies for effectively dealing
with both task and data parallelism in complex PDE
solvers, with particular emphasis on turbulent
combustion simulation. Specifically, directed acyclic
graph approaches for exposing task-level parallelism,
coupled with a domain-specific language that provides
matlab-like syntax and supports deployment on
multicore or GPU systems are discussed. Together,
these abstractions increase programmer productivity
while enabling more complexity in terms of physics and
hardware targets.
Using GPUs to accelerating nonstiff and stiff
chemical kinetics in combustion simulations
K. Niemeyer
Oregon State University, USA.
Combustion simulations with detailed chemical kinetics
require the integration of a large number of ordinary
differential equations (ODEs), with at least one ODE
system per spatial location solved every time step. This
task is well-suited to the massively parallel processing
capabilities of graphics processing units (GPUs), where
individual GPU threads concurrently integrate
independent ODE systems for different spatial
locations. However, the typical high-order implicit
algorithms used in combustion modeling applications
(e.g., VODE, LSODE) to handle stiffness involve
complex logical flow that causes severe thread
divergence when implemented on GPUs, thus limiting
the performance. Alternate algorithms are therefore
needed. This talk will discuss strategies and results
using integration algorithms for nonstiff and stiff
chemical kinetics on GPUs.
GPU based chemistry acceleration for
reacting flow simulations
J. Lee and V. Sankaran
United Technologies Research Center, USA.
Advances in GPU and their programmability make
them attractive for Computational Fluid Dynamics
(CFD). Here we benchmarked a hybrid CPU-GPU
paradigm by simulating an idealized, but fully resolved
combustion problem. This problem retained the
complexity of three dimensional turbulent reactive flow
physics including detailed chemistry, while neglecting
geometrical complexities. We achieved 2-5X overall
speed-up compared to CPU-only simulations. Further
details of the CFD problem, hybrid methodology,
performance metrics definition and benchmarking
results will be presented. This promising technology, if
exploited properly, could quickly enable accurate
predictions of finite rate chemistry effects, such as
pollutant emissions from combustors.
Accelerating combustion modeling with
the Intel Xeon Phi
C. Stone
Computational Science & Engineering, USA.
Promising speed-up of combustion simulations with
GPUs, particularly in regards to kinetics, has been
demonstrated over recent years. Here, we will examine
the speed-up potential of the Intel Xeon Phi coprocessor for combustion applications and compare to
GPU performance. Application benchmarks will be
presented using the Xeon Phi in isolation as well as in
tandem with the host CPU cores to demonstrate the
scalability in the heterogeneous environment. A novel
single-instruction multiple-data vectorization approach
will be presented that improves both Xeon Phi and host
CPU performance by a factor of between two to three
times compared to traditional implementation.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. MS7: Diagnostics for autoignition process 33 MS7: Diagnostics for autoignition processes
M. Valorani
Sapienza University of Rome, Italy.
The efficient design of combustion devices requires a detailed understanding on the dependence of basic autoignition
characteristics (e.g., ignition delay) to various operative conditions, such as type of fuel fuel, initial mixture fraction,
pressure and temperature, uncertain parameters, etc. In the past, researchers were resorting to analytic (mostly
asymptotic) methodologies, so that it was possible to analyze only the cases were a simple reduced model was available.
The development of alternative algorithmic methodologies has recently allowed the analysis of physical problems
modeled by complex kinetic mechanisms. This mini-symposium focuses on recent advances in the development of
algorithmic tools for the study of basic autoignition characteristic. It brings together experts from a wide range of
backgrounds working in computational combustion.
MS7 (1/2)
How details of fuel molecular structure can
accelerate or retard autoignition
C. Westbrook
This presentation will investigate the inherent
uncertainties in predicting ignition delays for a variety
of bio-fuels where many of the rate constants have been
estimated rather than the subject of detailed kinetic
studies. The constraints that ignition delay data may
provide on key parameters within these schemes will be
addressed.
LLNL, USA.
Autoignition of hydrocarbon and other fuels is
responsible for many important combustion properties
that affect fuel performance in practical systems and
fuel safety, and fuel molecular structure can have
important influences on autoignition rates. Kinetic
modeling can show how the presence of different C-H
bonds, C=C double bonds, the specific location of O
atoms in the fuel, the length of carbon atom chains, the
degree of branching in the fuel molecule, and other
factors can either accelerate or retard autoignition in
fuel molecules, and this presentation will discuss those
many factors.
Uncertainties in predicting the ignition properties of
biofuels: what constraints can measurements
provide?
A. Tomlin and E. Agbro
The developing explosive dynamics in the vicinity of
the third explosion limit of H2/air
E. Tingas1, T. Turanyi2 and D. Goussis3
1
National Technical University of Athens, Greece.
Eötvös University (ELTE), Hungary.
3
2
While the discussion on the first and second explosion
limits of H2/air mixtures seems to have come to an end,
the prevailing chemistry for the development of the
third limit is still a subject of research. This topic is
further investigated here by resorting to the CSP
algorithmic tools, in order to identify the reactions and
species that relate the most to the explosive modes, in
the case of a homogeneous constant volume mixture.
Two different sets of initial conditions are considered;
one below the third limit and one above (T0=800 K;
P0=1 atm and P0=5 atm, respectively).
Correctly predicting the ignition properties of fuels and
fuel mixtures is an essential component of chemical
mechanisms if they are to be used within models of
practical combustion
devices. Ignition
delay
measurements from a variety of apparatus including
low and high pressure shock tubes and rapid
compression machines is therefore commonly used as a
method of evaluating combustion mechanisms. For
newly developed mechanisms (e.g. for alternative/biofuels), such data has a role to play in providing realistic
parameterisations of key model inputs. Nevertheless,
such models still contain a high level of uncertainty.
Analytical prediction of syngas induction times
P. Boivin1, A. Sanchez2 and F. Williams3
1
IUSTI, CNRS and Aix-Marseille Université, France.
Universidad Carlos III de Madrid, Spain.
3
UCSD, USA.
2
Computations indicate that, under all possible
conditions of practical interest, including temperatures
both above and below the crossover temperature at
which the rates of the H2 + O2 branching and
termination steps are equal, eleven irreversible
elementary steps suffice to provide accurate values of
induction times in autoignition processes of fuels
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 34 MS7: Diagnostics for autoignition processes consisting of mixtures of H2, CO, and inerts. At high
temperatures, this time is controlled by the time
required for HO2 to reach a steady state, with heat
release being negligible during that time, while below
the crossover temperature, the time to reach this steady
state becomes shorter than the induction time, and the
heat release becomes non-negligible once HO2 has
reached a steady state, resulting in the induction time
progressively approaches that of a thermal explosion,
which includes an effectively autocatalytic production
of H2O2. Analytical approximations are introduced
here that enable induction times to be calculated
accurately under all conditions.
Optimal dimension of the combustion mechanism in
the ignition problem
approximation (up to a suitable order) of the slow
invariant manifold of n-dimensional slow fast
autonomous dynamical systems. Then the Flow
Curvature Method (FCM) will be applied for
determining an approximation of the slow invariant
manifold of the Van der Pol system in dimension 2, of
the Chua’s models in dimension 3, 4 and 5. Then, in
order to compare the FCM with the so-called
Computational Singular Perturbation Method (CSPM),
the slow invariant manifold of the “Davis–Skodje
problem” in dimension 2, of “a 3-species kinetics
problem” in dimension 3, of the Lorenz-Krishnamurthy
model in dimension 5 and of a model of a network of
coupled enzymatic reactions in dimension 6 will be also
analytically computed.
MS7 (2/2)
V. Bykov1, V. Gol'dshtein2 and U. Maas1
1
2
Karlsruher Institut für Technologie (KIT), Germany.
Ben-Gurion University of the Negev, Israel.
In order to model and analyse ignition process a very
detailed description of the chemical kinetics is required.
Therefore, typical combustion mechanisms have
become extremely large during the last few decades.
The question of an optimal dimension (as a number of
degrees of freedom required) to model and analyze the
ignition process accurately enough has become very
important but it is not answered yet in a general context.
In the proposed talk a combination of local (ILDM
based) and global (GQL based) approaches for
mechanism analysis is suggested that answers this
question. The methodology and results for its
application are illustrated and benchmarked by the
methane/air combustion system.
Flow curvature method applied to dynamical
systems analysis
J. Ginoux
Université de Toulon, France.
The Flow Curvature Method is based on the idea that
the trajectory curve, integral of any n-dimensional
dynamical system may be considered as curve in
Euclidean n-space having local metrics properties of
curvatures. Thus, the location of the points where the
curvature of the trajectory curve, integral of any ndimensional dynamical system, vanishes defines a
manifold called: flow curvature manifold. This
manifold (a curve in dimension, a surface in dimension
3, a hypersurface in higher dimension) enables to find
again the main features of such n-dimensional
dynamical system (fixed points and their stability,
center manifolds, local bifurcation of codimension
1,…). More particularly, it has been established that the
flow curvature manifold directly provides an
The developing explosive dynamics during the
autoignition of a DME/air mixture
E. Tingas1, D. Kyritsis2 and D. Goussis1
1
National Technical University of Athens, Greece.
Department of Mechanical Engineering, Khalifa University, Abu
Dhabi, UAE
2
Bio-DME is currently being considered as a potential
second-generation biofuel that can be produced from
ligno-cellulosic biomass. Using a detailed chemical
kinetics mechanism (1542 reactions and 253 species),
the reactions and species related to the generated
explosive modes are identified in the case of a
homogeneous constant volume DME/air mixture, where
phi=1, P0=50 atm and T0=1,100 K. The analysis is
based on various CSP algorithmic tools. The role of the
developing explosive modes is examined and
conclusions are drawn regarding the chemical-thermal
coupling that control the process. The influence of
various additives (i.e., CH4, CH2O etc) on ignition
delay is examined.
Numerical investigation of ignition in laminar
methane/LOx flamelet at supercritical pressures
P. Lapenna, P. Ciottoli, F. Creta and M. Valorani
University of Rome "La Sapienza" Dept. of Mechanical and
Aerospace Engineering, Italy.
High-pressure combustion devices, such as liquid
rocket engines, are characterized by transcritical and
supercritical conditions which influence ignition
processes. In the present study, real fluid effects on both
forced and auto-ignition phenomena are investigated in
the framework of unsteady laminar flamelet equations,
which provide a well established representation and
diagnostic tool for non premixed combustion transient
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. MS7: Diagnostics for autoignition processes 35 phenomena. Real fluid properties are taken into account
using a computationally efficient cubic equation of
state, written in a comprehensive three-parameter
fashion. High pressure conditions for unsteady flame
structure calculations are representative of a
methane/liquid-oxygen rocket engine operating
conditions.
hot spots leading to ignition front propagation, and is
considered to be the main cause for the discrepancies in
the prediction of the ignition delay times. The present
study reports 1D and 2D parametric studies of
computational simulations to represent the distinct
ignition characteristics. Further scaling consideration
leads to a diagram to map out parametric conditions in
which different ignition regimes are identified.
Impact of pilot injections on ignition behaviour at
low in-cylinder temperatures from extreme miller
valve timing in a heavy-duty Diesel engine
S. Pandurangi, Y. Wright, C. Brückner, P. Kyrtatos and
K. Boulouchos
ETH Zürich, Aerothermochemistry and Combustion Systems
Laboratory, Dept. of Mechanical Engineering
Simulations of a heavy-duty single-cylinder research
Diesel engine operating with pilot injections at extreme
Miller valve timing leading to end-of-compression
temperatures between 710–790 K have been performed
with a 3D CFD solver, coupled with the conditional
moment closure (CMC) combustion model. The
influence of adding pilot injections is studied,
concerning their impact on auto-ignition, heat release as
well as soot and NOx formation. An extended CMC
model, capable of incorporating an arbitrary number of
injection events, is employed. An embedded twoequation soot model is included while NOx is
calculated using the Zeldovich mechanism. Predicted
apparent heat-release rates and their response to pilot
injections are in very good agreement with experiments.
Numerical results are subsequently employed to gain
further insight into the impact of pilot injection on sootspecific processes such as formation and oxidation, as
well as on NOx emissions. The auto-ignition behaviour
is further elucidated by discussion of evolutions of
conditional quantities as predicted by CMC. The
findings suggest that the extended CMC model shows
considerable promise for the simulation of Diesel
engines operating with multiple injections under
extreme-Miller conditions.
Regimes of auto-ignition in homogeneous reactant
mixtures with temperature fluctuations
H. Im1, P. Pal2, M. Wooldridge2 and A. Mansfield2
1
2
King Abdullah University of Science and Technology, Saudi Arabia.
“Mild” and “strong” ignition phenomena have been
experimentally observed in shock tubes and rapid
compression machines in which the mixture condition
is expected to be nearly homogeneous. The “mild”
ignition behavior is attributed to early auto-ignition of
Auto-ignition diagnostics using the tangential
stretching rate concept
M. Valorani1 and S. Paolucci2
1
2
Sapienza University of Rome, Italy.
University of Notre Dame, USA.
We analyze ignition phenomena by resorting to a
Tangential Stretching Rate (TSR) parameter which
combines the concepts of stretching rate in dynamical
systems with the decomposition of the local tangent
space in eigenmodes. The main feature of TSR is its
ability to identify unambiguously the most energetic
scale at a given space location and time instant. The
TSR of a state function can be readily computed during
the post processing of reactive flow fields data. We
verified the properties of the TSR with reference to
different simple model problems and for the autoignition of hydrocarbon fuels.
Investigation of the effect of correlated uncertain
rate parameters on a model of hydrogen combustion
using a generalized HDMR method
É. Valkó1, A. Tomlin2, T. Varga1 and T. Turányi1
1
2
Energy Research Institute, University of Leeds, UK.
The High Dimensional Model Representation (HDMR)
method has previously been applied to obtain global
sensitivity indices of uncorrelated model parameters for
several combustion systems. Here a generalized HDMR
method was obtained by using the Rosenblatttransformation on a correlated model parameter sample
to obtain a sample of independent normally distributed
variables. The sensitivity indices were calculated for
these transformed variables using the HDMR method.
This generalized HDMR method was applied for the
determination of sensitivity indices of a hydrogen
combustion model, knowing the covariance matrix of
rate parameters. The effect of the correlation of the rate
parameters was investigated on the calculated
uncertainty of ignition delay times of hydrogen
combustion at various initial conditions.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 36 MS8: Modeling and computation of detonations in high-‐energy explosives MS8: Modeling and computation of detonations in high-energy explosives
A. Kapila and D. Schwendeman
Rensselaer Polytechnic Institute, USA.
Detonations in condensed-phase, high-energy explosives present special challenges not only in experiment but also in
modeling and computation. This mini-symposium gathers four presentations that focus on the modeling and
computation of detonation initiation and propagation in practical explosives, addressing different but related aspects of
the problem. The issues addressed include sensitivity of detonation initiation to initial porosity and initiating stimulus,
hot-spot generation due to binary cavity collapse, role of confinement in transition to detonation, and development of an
accurate numerical framework that applies shock-capturing to detonation propagation.
Sensitivity of run-to-detonation distance in
practical explosives
Propagation of detonations in curved geometries of
compliantly confined solid explosives
J. Gambino, D. Schwendeman and A. Kapila
E. Ioannou, L. Michael and N. Nikiforakis
Rensselaer Polytechnic Institute, USA.
In condensed-phase explosives, run-to-detonation
distance subsequent to the application of an initiating
stimulus is an important measure of both performance
and safety. This study, which continues our work on
the evaluation of multi-phase DDT models, considers
practical HMX-based granular explosives, models them
as two-phase materials, employs realistic constitutive
input including equations of state and chemical kinetics,
and examines the sensitivity of the run-to-detonation
distance to system parameters including the initial
porosity and the initiating stimulus.
Results are
compared with recently-obtained experimental data.
Challenges encountered in the computational process
are also discussed.
This study deals with the propagation of detonation
waves in a solid explosive which is compliantly
confined within a duct with straight and curved
sections. The focus is on the process of transition to
steady state after the detonation wave has entered the
curved region. Previous studies have suggested that the
transition is characterized by an exponential decay of
the outer wall detonation velocity. We show that this is
only part of the process, as local effects also play a role
in the early stages and can be prominent or not,
depending on the specific parameters of the curved
geometry.
Application of two-dimensional shock-fitting to
detonation propagation in high explosives
Coupled simulations of condensed-phase explosives
and elastic-plastic solids
T. Aslam1 and C. Romick2
1
L. Michael and N. Nikiforakis
This research is concerned with the simulation of
combustion and transition to detonation of condensedphase explosives, which are confined by (or in general
interacting with one or more) compliant inert materials.
We couple the chemically active model for the
explosive to an elastic-plastic model in the case of solid
confiner and a separate fluid model for fluid inert
materials. The ghost-fluid method is used to evolve the
explosive/inert material interface and the coupling is
achieved by means of an approximate mixed Riemann
solver. Examples of such simulations are presented.
2
Los Alamos National Laboratory, USA.
University of Notre Dame, USA.
A highly accurate numerical shock-fitting scheme
composed of fifth order spatial and third order temporal
discretizations is applied to the two-dimensional
reactive Euler equations. The steady detonation phase
speed that results from this scheme was compared with
the equivalent from shock-capturing. It was found that,
unlike a shock-capturing scheme, the shock-fitting
scheme allowed for the steady detonation phase speed
to converge at higher than first order while the errors at
the coarser solutions were significantly reduced in
comparison with shock-capturing. Several examples are
given, demonstrating efficiency gains of O(100010000) for shock-fitting versus shock-capturing.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. MS9: High-‐fidelity coupled simulation of reacting systems 37 MS9: High-fidelity coupled simulation of reacting systems
F. Duchaine and L. Gicquel
CERFACS, France.
Multiphysics, multi-scale and multi-component simulations will play an increasing role for better understanding of
reacting flows or in the design of new technologies. Indeed, although complex fluid motions are of prime importance for
first order flow predictions, higher quality numerical predictions will require advanced Computational Fluid Dynamics
(CFD) coupled to more physics. In many fields (combustion, rotating machines, aerodynamic, acoustic...) unsteady flow
methods such as Large Eddy Simulation (LES) or Direct Numerical Simulation (DNS) give already very accurate results.
The step forward is hence to couple these solvers with other physics to compose multiphysics, multi-component
frameworks addressing coupled real flows. The symposium on " High fidelity coupled simulations of reacting systems "
aims at bringing together international researchers and engineers involved in the development and/or use of coupled
solutions. Specific but not limited topics include aerothermal, aeromechanics and aeroacoustic with interests in
applications, models, HPC, methodologies, framework...
MS9 (1/2)
Large eddy simulation and the filtered probability
density function method
and detailed reaction mechanisms and experimental
combustor data will be used for validation of the global
and skeletal reaction mechanisms and the LES
combustion model, respectively.
Coupling approach to account for heat losses in a
practical combustor
W. Jones
In large eddy simulation of combustion flows a method
is needed to account for the influence of unresolved
sub-grid-scale motion on chemical reaction rates. The
evolution equation for the filtered fine grained or subgrid joint probability density function of the scalars
quantities needed to describe reaction represents a basis
on which such a model can be constructed. Because of
the large dimensionality of the equations stochastic
solution techniques are required. For this the Eulerian
stochastic field solution method is adopted. The
capabilities of the approach will be illustrated by
comparisons of LES results with measurements in a
range of configurations.
Heterogeneous multi-scale LES using skeletal
reaction mechanisms
C. Fureby, N. Zettervall and K. Nordin-Bates
The Swedish Defence Research Agency - FOI, Sweden.
In the paper to be presented we plan to examine the use
of skeletal reaction mechanisms in heterogeneous multiscale Large Eddy Simulations (LES) of turbulent
combustion. Physical, chemical as well as numerical
aspects will be discussed, and LES results, using global
and skeletal reaction mechanisms, will be presented and
discussed for an engineering application involving a
premixed turbulent bluff-body stabilized flame.
Comparison with laminar flame data from experiments
D. Mira1, M. Zavala-Ake1, S. Gövert2, J. Kok2,
M. Vazquez1 and G. Houzeaux1
1
2
BSC-CNS, Spain.
University of Twente, The Netherlands.
Heat transfer is a key issue to evaluate the overall
performance and life duration of practical systems. The
heat losses carry a reduction in efficiency that
eventually might lead to an economical cost and
potential failure. The understanding of the distribution
of heat in thermal devices is not only beneficial to
improve particular operating conditions, but also to
enhance aerodynamic, thermal design, and selection of
appropriate materials for a given application.
The proposed work addresses the modelling of heat
losses using a conjugate-heat transfer approach in the
context of large-eddy simulation (LES). The emphasis
is given to the analysis of thermal stresses on the solid
domain with its corresponding boundary conditions for
a given operating condition of the combustor. The
exchange of information between fluid and solid
domains is performed using a parallel coupler and the
application case is a combustor subjected to strong heat
losses.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 38 MS9: High-‐fidelity coupled simulation of reacting systems Analysis of large-eddy simulations of
laboratory-scale fire
M. Rochoux1, B. Cuenot2, F. Duchaine2, E. Riber2,
D. Veynante3 and N. Darabiha3
Aerothermal prediction of an aeronautical
combustion chamber based on the coupling of largeeddy simulation, solid conduction and radiation
numerical solvers
S. Berger1, F. Duchaine2, L. Gicquel2 and S. Richard3
1
Meteorological Research Division - Environment Canada, Canada.
CERFACS, France.
3
2
1
2
3
A large-eddy simulation (LES) approach, coupling
combustion with radiation heat transfer and biomass
fuel pyrolysis, is proposed to solve for the buoyant
flame structure specific to natural fire propagation.
These multi-physics coupled simulations of fire
propagation are performed at laboratory scale and are
compared to measurements to provide a comprehensive
understanding of the mechanisms as well as of the
characteristic time-/length-scales underlying fire
propagation. This approach is found promising to
examine the assumptions used to estimate the rate of
spread as well as the emission factors, the modeling
amount of species released in the atmosphere.
MS9 (2/2)
CERFACS / TURBOMECA, France
CERFACS, France.
TURBOMECA, France.
Wall temperature evaluation is a multiphysics problem
that can be solved numerically jointly through the use
of several dedicated numerical and algorithmic
approaches. In this paper, the partitioned coupling
methodology used relies on a high fidelity Large Eddy
Simulation (LES) reacting flow solver coupled to a
conduction and radiation solvers. A efficient parallel
coupling of the three solvers is obtained thanks to a
code coupler that manages the parallel execution of the
parallel codes as well as the exchange of data between
each physics. Issues linked to the performance and the
accuracy of such high-end coupled simulations are
addressed and the effect of each physical component of
the coupled simulation is discussed based on a real
industrial burner application.
st
Automatic determination of the coupling period in
unsteady conjugate heat transfer. Application to
large-eddy simulation of flame-wall interaction
1
2
C. Koren , R. Vicquelin and O. Gicquel
A 3D coupled approach for the thermal design of
aero-engine combustor liners
A. Andreini, B. Facchini and L. Mazzei
Department of Industrial Engineering - University of Florence, Italy.
2
1
Air Liquide - Laboratoire EM2C, CNRS and Ecole Centrale Paris,
France.
2
Combustors’ increase in size and power leads to a need
of better estimation of wall heat fluxes. To reach this
goal, coupled numerical simulations are carried out
using state of the art numerical tools for each physical
phenomenon. One of the main issues for such an
approach is the determination of an accurate and
efficient coupling period between the different solvers.
We present an approach where this coupling period is
automatically determined. For conjugate heat transfer, a
hybrid cells layer that overlaps on both domains enables
to derive an ordinary differential equation (ODE) for
the wall temperature. Mathematical framework for time
step adaptation in ODEs is then used to estimate the
coupling frequency for a given error criterion. After
being validated in one-dimensional tests, this approach
is carried out in a 3D case of flame-wall interaction.
The implementation of lean burn concept in modern
aero-engine combustors involves a significant reduction
in the available coolant amount. In order to limit the
computational effort due to the presence of effusion
cooling, the proposed 3D coupled approach for metal
temperature estimation relies on the accurate prediction
of hot side heat loads through CFD, modelling coolant
injection with local mass sources, whereas an external
code provides mass flow rate and heat loads on the cold
side, where the flow field can be approximated reliably
through a correlative approach. The application of the
procedure to a representative test case is presented in
this work.
Towards coupled simulation of aero-engines HP
system using industrial CFD solvers
P. Legrenzi
Loughborough University, UK.
This work aims to develop a reliable and robust
methodology to couple two existing industrial CFD
solvers for the simulation of compressor-combustor and
combustor-turbine interactions in an aero-engine gas
turbine. A low-Mach number pressure-based code
specialised for combustion systems and a compressible
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. MS9: High-‐fidelity coupled simulation of reacting systems density-based code specialised for turbomachinery
applications are computed simultaneously, each in its
own domain, exploiting a zonal coupling type of
approach. Two communication methodologies, file
based and memory based, have been used for steady
39 and unsteady RANS simulations respectively. Testing is
carried out using simplified geometries. The approach is
applied to a real combustor-turbine interaction problem.
MS10: LES modeling of oxy-coal combustion
Wednesday April 22nd (10h00 – 12h00)
A. Sadiki1 and H. Pitsch2
1
2
Technische Universitaet Darmstadt, Dept. of Mechanical and Processing Engineering, Germany.
RWTH Aachen University, Germany.
A major part of the carbon dioxide emissions due to human activities come from fossil fuels. Three main approaches are
currently used to capture such undesirable carbon dioxide, namely, pre-combustion capture, post-combustion capture,
and oxy-fuel combustion. Oxy-coal combustion is energetically favorable, but features complex unsteady fluid flow,
mass and heat transfer interaction processes along with heterogeneous combustion and radiation in an atmosphere that is
not usually studied. In order to foster the understanding of these interacting processes and to support the exploration of
design concepts for oxy-fuel burners, boilers and combustors while minimizing trial-and-error iterations, reliable CFD
tools are essential. During this mini-symposium, some efforts related to developing CFD for oxy-coal combustion will be
reported and discussed. Especially CFD tools based on Large-Eddy Simulation related techniques are considered. Four
well-known research groups from Germany (TU-Darmstadt, RWTH-Aachen), Poland (TU- Częstochowa), USA (Utah
University) and USA (Sandia-Lab.) will address this topic.
Developing and validating an oxy-fuel CFD
modelling methodolody
R. Knappstein1, A. Kethelheun1, G. Kuenne1, S. Farazi2,
M. Baroncelli2, A. Sadiki1, H. Pitsch2 and J. Janicka1
1
2
Technische Universitaet Darmstadt, Germany.
Oxy-fuel combustion is recognized as one of the
advanced clean fossil fuel technologies to allow for
capturing CO2. This contribution reports on current
efforts achieved in developing and validating a CFD
modelling methodology for oxy-fuel combustion.
Relying on Large Eddy Simulation techniques, this
modelling approach will enable to provide early
information and analysis of intrinsically unsteady fluid
flow, mixing and reaction characteristics of complex
oxy-fuel combustion systems. An advanced flamelet
based tabulated strategy with a detailed chemistry
mechanism will be used. The modelling endeavors are
closely supported by both DNS and experimental data
for validation.
LES and RANS of pulverized coal oxy-combustion
in swirl burners
A. Bogusławski and P. Warzecha
Czestochowa University of Technology, Poland.
The contribution presents the results of numerical
simulations of pulverized coal combustion process in
swirl burners using RANS and LES methods for
turbulent flow in two test facilities with swirl burners
for combustion in air and in O2/CO2 atmospheres.
Most of the numerical simulations of pulverized coal
oxy-combustion process have been done using RANS
method. Therefore authors took an attempt to analyze
the influence of turbulence model on the results of
pulverized coal oxy-combustion technology. The test
cases analyzed show clearly that proper modelling of
underlying turbulent flow is crucial for quality of
combustion process predictions.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 40 MS10: LES modeling of oxy-‐coal combustion Oxy-coal power boiler simulation and validation
through extreme computing
Transported probability density function modeling
of pulverized coal combustion
P. Smith, J. Thornock, Y. Wu, S. Smith and B. Isaac
X. Zhao
Sandia-Lab, USA.
We have studied the operation of a 15 MW boiler under
oxy-coal firing with flue gas recirculation for carbon
capture. This study was performed using highperformance-computing (HPC) at an extreme scale and
dynamic large eddy simulation. These techniques
allowed for 1-2 cm resolution of turbulence structures
within the boiler and its temporal resolution at
microsecond time scale. All of the scales of the particle
transport and reaction are fully resolved for the entire
particle size distribution. Particle size segregation and
clustering are spatially and temporal resolved.
Experimental measurements collected in an ALSTOM
Boiler Simulator Facility are used for validation.
A transported probability density function method has
been constructed to model the process of pulverized
coal combustion. A Lagrangian particle/Eulerian mesh
(LPEM) algorithm has been employed for the gas
phase, and a particle-source-in-cell method is applied to
the solid phase. Gas-phase chemistry is accounted for
by detailed chemical mechanisms. Temperature, gasphase concentrations, and ignition properties are
calculated. Parametric studies are carried out, including
the variations in turbulence models, turbulent
combustion models, heat transfer models, and the
phase-coupling models.
MS11: Surface evolution methods in gasoline direct injection combustion engines
J. Hahn and P. Priesching
AVL List GmbH, Austria.
In this minisymposium, we focus on extension of advanced numerical methods on surface evolution into a general
unstructured mesh and their practical usages of gasoline direct injection combustion engines. In surface evolution, level
set (Eulerian) methods and direct (Lagrangian) methods are reviewed and novel high order explicit and semi-implicit
finite volume level set methods are proposed on general computational meshes. An efficient and fast parallel computing
of proposed methods is discussed on cell-based overlapping domain prevalent in many commercial numerical CFD
softwares. Even if each domain only allows to contain the first neighboring buffer cells, a high experimental order of
convergence is obtained. In the context of application examples, contemporary standard and innovated numerical
methods in combustion engine simulation from BMW, Germany and AVL, Austria are presented. Moreover, future
challenges in gasoline engines are discussed in the view of practical necessity in real application.
A flame surface tracking method for calculating the
premixed combustion in engines
calculations are based on measured data from a variety
of application examples.
P. Priesching
A new modeling approach for the calculation of
premixed combustion is presented. This model is able
to track the flame surface in a quite accurate manner,
based on the combination of a Lagrangian and Eulerian
method. Comparisons to other modeling approaches are
discussed. In the context of application examples it is
outlined, which problems generally dominate in
developing spark ignited combustion engines today and
how CFD based methods can help to better understand
combustion and emission phenomena. Results of the
Regularized flux-based gradient for
level set methods
J. Hahn
We propose a regularized flux-based gradient method to
solve surface evolution equations in level set literature.
Unlike to using a standard structured mesh, the
proposed method extends well-known advantages in
level set method for surface evolution into a general
unstructured mesh. A high experimental order of
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. MS11: Surface evolution methods in gasoline direct injection combustion engines convergence is obtained by a regularized gradient
computation with compatible discrete operators. An
efficient and fast parallel computing is also achieved on
cell-based overlapping domains which only allow to
have the first neighboring cells. Standard examples in
surface evolution and combustion models are
numerically investigated to show the advantage of
regularized flux-based gradient method.
evolved by nonlinear advection-diffusion equation, and
we present novel high order explicit and semi-implicit
finite volume level set methods suitable for
computations on general Eulerian computational grids.
Simulation of turbulent premixed combustion in
turbocharged direct injection gasoline engines using
a level set based flamelet model
D. Linse
Finite volume methods for evolving surfaces
K. Mikula, P. Frolkovic and M. Remesikova
Department of Mathematics, Slovak University of Technology,
Slovakia.
We present and discuss new finite volume numerical
schemes for evolving surfaces both in level set
(Eulerian) and direct (Lagrangian) formulations. The
methods are capable to solve precisely and in a stable
way the complex surface evolutions advected by
external vector fields and mean curvature as arising in
flame front propagation in numerical combustion. In the
Lagrangian formulation, a triangular surface
representation is evolved and crucial point for stable
and robust computations is usage of a proper
redistribution of discrete nodes along the surface. In the
level set formulation, the so-called level set function is
41 BMW Group, Germany.
We have implemented the G-equation, a level-set based
flamelet model, into the 3D-CFD Solver ANSYS CFX.
It has proven in recent years to be successful in
predicting the turbulent flame front propagation for
turbulent premixed combustion. In this talk we discuss
the applicability of level set based approaches for the
simulation of combustion in turbocharged direct
injection spark ignition engines. Special emphasis is put
on the characterization of the interaction of turbulence
and flame structure. Finally, current and future
challenges for the simulation of combustion in gasoline
engines are highlighted.
MS12: Safety related ignition process
D. Markus1, U. Maas2 and D. Thévenin3
1
Physikalisch-Technische Bundesanstalt, Germany.
3
University of Magdeburg, Germany.
2
The interaction of the various transport processes with chemical reactions during an ignition process is a multi scale
problem which comprises several time and length scales and different physical and chemical phenomena. Therefore,
models to describe ignition processes have to consider a large number of parameters. Especially in the case of safety
relevant ignition processes the challenge remains to cover turbulence, plasma processes, heterogeneous and
homogeneous combustion etc. This mini‐symposium covers different ignition sources near the minimum energy
necessary for ignition. Additionally, the impact of turbulence and mixing on a successful ignition event are investigated.
MS12 (1/2)
Ignition in a premixed propane/air gas by turbulent
jets of its exhaust products
A. Ghorbani1, S. Fischer2, G. Steinhilber2, D. Markus1
and U. Maas2
1
2
Physikalisch-Technische Bundesanstalt (PTB), Germany.
The ignition of a combustible environment by hot jets is
a safety concern in many industries and understanding
the ignition of combustible mixtures by its exhaust
products plays an important role in explosion
protection. This work addresses numerical aspects of
the investigation of such configuration. Calculations are
preformed using a probability density function (PDF)
method in conjunction with a reaction-diffusion
manifold (REDIM) which is used to reduce the number
of dependent variables in the description of the
thermochemical state. The test case considered in the
current work are combustion of premixed hydrogen/air
and propane/air gases which are among the exemplary
fuels in the investigation of maximum experimental
safe gaps (MESG).
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 42 MS12: Safety related ignition process DNS of plasma-assisted ignition in quiescent and
turbulent flow conditions
M. Castela1, B. Fiorina1, O. Gicquel1, A. Coussement2,
C. Laux1 and N. Darabiha1
1
2
Université Libre de Bruxelles, FSA, Belgium.
This numerical study focuses on the ignition of CH4-air
mixtures by nanosecond repetitively pulsed electric
discharges. A sequence of pulses is computed by means
of Direct Numerical Simulations where different initial
conditions of turbulence and pulse frequencies are
considered. This work examines the impact of the
oxygen dissociation, temperature and production of
vibrational states of molecules induced by the plasma
discharges on the flame kernel formation and
propagation. The results show a minor contribution of
the discharge energy stored as gas vibrational energy on
the initial stage of ignition. In turn, the early production
of O atoms favors the initial branching reactions
increasing the concentration of radicals in the vicinity
of the discharge zone. The initial condition of
turbulence inside the discharge zone impacts on the
number of pulses needed to ignite the mixture.
Direct numerical simulation of the auto-ignition of
turbulent ethylene/air mixtures
A. Abdelsamie and D. Thévenin
University of Magdeburg "Otto von Guericke", Germany.
The probability of auto-ignition of turbulent
ethylene/air mixtures has been examined by means of
Direct Numerical Simulations. Various configurations
(isotropic homogenous turbulence and jet, in 2D and in
3D) are considered. The impact of different parameters
(initial temperature, pressure, equivalence ratio and
shear) has been quantified. The UCSD mechanism (64
species, 235 elementary reactions) is used based on
Cantera 1.8 to obtain kinetic, thermodynamic and
transport properties in the DNS. First results show that
2D DNS are sufficient to predict auto-ignition
probability, but further comparisons are needed to
generalize this observation.
Analysis of ignition regimes in rapid
compression machines
M. Ihme1, K. Grogan2 and S. Goldsborough3
1
no affiliation
3
2
Rapid compression machines (RCMs) are used to study
ignition properties of different fuels over a wide range
of pressure and temperature conditions. This results in
accessing different ignition regimes, which are
currently not fully understood. This presentation gives
an overview about relevant system-describing
quantities. Essential parameters associated with
turbulence, ignition chemistry, and heat-transfer are
identified, and a regime diagram is constructed to
delineate different ignition phenomena. Comparison
with measurement are performed to validate the
theoretically developed regime diagram.
MS12 (2/2)
Numerical investigation of ignition over
heated spheres
J. Melguizo-Gavilanes and J. Shepherd
California Institute of Technology, USA.
Ignition of combustible atmospheres by hot particles is
a common issue in industrial safety. Results show the
importance of flow separation in creating zones
conducive to ignition. Far from the ignition threshold,
reaction starts upon contact with reactive mixture, and
ignition times are comparable to or less than the transit
time of a parcel of fluid from front stagnation point to
the separation. Closer to the threshold however, the
volume of gas confined in the separation region ignites
homogeneously after a longer induction time.
Competition between convective losses and heat
addition due to chemical reaction is dynamic in this
regime, with quenching and re-ignition events observed.
Ignition at sub-millimeter sized hot particles: a
numerical and experimental study
D. Roth, T. Häber and H. Bockhorn
Karlsruhe Institute of Technology (KIT), Engler-Bunte-Institute
(Combustion Division), Germany.
Mechanical sparks are small hot particles formed in
mechanical shaping processes like grinding and
hammering. If these glowing, hot particles come in
contact with an explosive gas mixture they may cause
an ignition event. We investigate numerically and
experimentally the required conditions and governing
influences to achieve ignition of combustible-air
mixtures by sub-millimeter sized particles. In favor of
experimental and computational accessibility the
particle generation and consecutive movement will be
neglected, thus we cover ignition processes caused by
spherical particles in quiescent atmospheres. The
surface temperature needed to achieve ignition
correlates well with the minimum ignition energy of
various combustibles.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. MS12: Safety related ignition process 43 Methanol ignition by a line energy source embedded
in a wall
Quasi-spectral element method for numerical
integration of stiff unsteady combustion systems
M. Sanchez-Sanz, E. Fernandez-Tarrazo and A.
Sanchez
A. Koksharov, V. Bykov and U. Maas
Universidad Carlos III de Madrid, Spain.
We consider the transient near-isobaric ignition process
of a semi-infinite methanol-air mixture following the
sudden application of a constant heat flux from a line
energy source placed along a bounding flat wall. In
contrast with the case of an infinite atmosphere, when
the resulting problem is axisymmetric and the
momentum equation becomes secondary for the
computation of the temperature and velocity fields, the
solution involves in this case the integration of the
Navier-Stokes equations, supplemented by the energy
and species conservation equations. The description of
the ignition history provides information of interest in
connection with the problem of micro-scale combustion
in rotary engines.
Although a typical combustion system is both stiff in
time and in space, within an appropriate scale the
solution remains sufficiently smooth. This property is
used to approximate the solution with a set of
polynomials over a proper space-time grid, which
consists of a minimal set of irregular elements in space
and time providing the solution approximation with the
defined tolerance. Starting with a polynomial family
and a provided tolerance our method dynamically
optimises the distribution and the number of elements
during the system integration. This method is
benchmarked by 1D premixed hydrogen ignition
problems using different polynomials.
MS13: Flame topology
S. Cant
The dynamics of turbulent flame propagation and extinction depend strongly on the local geometry of the flame surface.
Statistical analysis of quantities such as the flame surface curvature has already yielded a great deal of useful
information. More advanced methods based on ideas from topology are now emerging which allow for a more detailed
understanding of the local flame behaviour and its dependence on interactions with the surrounding turbulent flow field.
The minisymposium brings together four distinctively different approaches to the common theme of flame topology.
These novel topological analysis methods are based on the extensive use of DNS data, including some of the largest
available datasets. New results have been obtained for the topology of flame-flame interaction, the tracking of flame
extinction holes, and the influence of flame geometry and flame alignment on propagation. New insight has been gained
which will assist in the future development of models.
Topology of turbulent premixed flame interaction
R. Griffiths1, H. Kolla2, W. Kollmann3, J. Chen2
and S. Cant1
1
3
University of California Davis, USA.
occurrence of each type of interaction topology for two
different Damkohler numbers cases. Inferences are
drawn concerning the underlying physical processes
behind each of the observed interaction types.
2
Flame-flame interaction is an important contributor to
flame surface area production and destruction in
turbulent premixed flames. The present work makes
use of a general method for finding the critical points of
line, surface and volume-type geometrical features. A
large DNS database for turbulent interacting hydrogenair flames is analysed and a complete set of flame
interaction topologies is identified using surface shape
factors. Statistical data is obtained on the frequency of
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 44 MS13: Flame topology Extinction and reignition dynamics in turbulent
dimethyl ether jet flames
Effective normal strain rate and scalar gradient
enhancement
A. Bhagatwala1, E. Hawkes2, P. Bremer3, A. Gyulassy4
and J. Chen1
L. Cifuentes1, C. Dopazo1, J. Martin1, P. Domingo2,
L. Vervisch2 and C. Jimenez3
1
University of New South Wales, Australia.
3
Lawrence Livermore National Labs, USA.
4
2
Recent direct numerical simulations of turbulent dimethyl ether temporal slot jet flame at a jet Reynolds
number of 13,050 and low Damkohler number are used
to understand the mechanisms of local extinction and
re-ignition. Topological segmentation methods are used
to understand the spatio-temporal dynamics associated
with the creation and healing of extinction holes and
their dependence on turbulent strain, stretch, and
mixing. Conditional statistics following topological
structures undergoing extinction and re-ignition will be
presented.
Interactions of turbulence and scalar structures in
shear-driven premixed turbulent flames using DNS
H. Wang1, E. Hawkes1, H. Kolla2 and J. Chen2
1
School of Mechanical and Manufacturing Engineering, UNSW,
Australia.
2
Combustion Research Facility, Sandia National Laboratories, USA.
1
LIFTEC, CSIC-University of Zaragoza, Spain.
CORIA - CNRS, Normandie Université, INSA de Rouen, France.
3
Department of Energy, CIEMAT, Spain.
2
Two DNS datasets for turbulent premixed flames
(Flame-A: inflow-outflow configuration; Flame-B: Jet
in a co-flow) are used to investigate local flow
topologies and scalar iso-surface geometries [1]. The
scalar-gradient modulus, |∇ Y|, evolution depends on
the sign of (a_N+ ∂V^Y /∂ x_N), the ‘effective’ strain
rate normal to the iso-scalar surfaces [2]. This study
aims at characterizing the ‘effective’ normal strain rate
for different scalar field geometries and flow topologies
for Flame-A [1] and Flame-B [3].
References
[1] L. Cifuentes, C. Dopazo, J. Martin, and C. Jimenez. Local flow
topologies and scalar structures in a turbulent premixed flame. Phys.
Fluids, 26 (6):065108, 2014.
[2] C. Dopazo, L. Cifuentes, J. Martin, and C. Jimenez. Strain rates
normal to approaching iso-scalar surfaces in a turbulent premixed
flame (under review). Combustion and Flame, 2014.
[3] L. Cifuentes, C. Dopazo, J. Martin, P. Domingo, and L. Vervisch.
Local volumetric dilatation rate and scalar geometries in a premixed
methane-air turbulent jet flame. Proc. Combust. Inst., 35, 2014.
Direct numerical simulations of lean H2/air flames in a
temporally evolving premixed slot-jet configuration are
employed to investigate the alignments of vorticity,
strain rate, and reacting scalar gradient. It is found that
at early times, dilatation from heat release dominates,
and the flame normal n is aligned preferentially with the
most extensive strain e1. As the flame front interacts
with the shear, local strain rate dominants and the
alignments are close to those in non-reacting flows.
Local flow patterns are identified using the invariants of
the deformation rate tensor, and they are shown to be
connected with the alignment characteristics.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP1: Soot 45 CONTRIBUTED PRESENTATIONS
CP1: Soot
CP1 (1/2)
Large eddy simulation of soot formation
in an oxy-coal combustor
Accounting for strain-rate effects in soot modeling
of turbulent flames
B. Franzelli1, A. Cuoci2, A. Stagni2, C. Saggese2,
A. Frassoldati2, T. Faravelli2 and M. Ihme3
1
Laboratoire EM2C (CNRS - Ecole Centrale Paris, France) - CTR
(Stanford University, USA).
2
Politecnico di Milano, Italy.
3
CTR, Stanford University, USA.
The objective of this work is to identify the impact of
reduced descriptions for the modeling of the soot
production in turbulent flames. The performance of a
reduced soot model is here compared against a detailed
description. In a first approach, the role of turbulence on
the soot production is examined in the context of a onedimensional counterflow diffusion flame. To introduce
curvature and transient effects, a two-dimensional
configuration of a flame/vortex interaction is then
investigated. Results show that strain rate and curvature
have a strong effect on the soot production, which has
to be accounted for by the reduced description.
D. Lignell1, A. Josephson1, B. Isaac2 and T. Fletcher1
1
2
Brigham Young University, USA.
Large eddy simulation (LES) of a 100 kW coal-fired
oxy-fuel combustor is presented. Oxy-coal combustion
is a promising technology for carbon capture in coalfired power plants. The combustor is a 1.7 m long, 0.6
m diameter, down fired unit. We compare simulation
results to experiments including heat flux, temperature,
and exit compositions.
Soot formation in coal
combustion is important for accurate capture of
radiative emission and flame temperatures.
Soot
formation is modeled using a method of moments. We
present results of a coal soot model, and uncertainty
quantification of key soot rate parameters and
representation of the particle size distribution.
Sensitivity of soot production to gaseous kinetic
models in LES of aero-engine combustors
B. Franzelli1, E. Riber2, B. Cuenot2 and M. Ihme3
1
Lewis number effects in turbulent nonpremixed
sooting flames
A. Attili1, F. Bisetti1, M. Mueller2 and H. Pitsch3
1
3
Aachen University, Germany.
2
Two direct numerical simulations of planar nheptane/air turbulent jets are compared to assess the
effect of the gas-phase species diffusion model on soot
formation and growth. The statistics of temperature and
major species obtained with a mixture average
formulation are very similar to those in the unity Lewis
number case. The total mass of PAH precursors
decreases by 10 to 20% with the Le=1 approximation,
but their distribution is more homogeneous in space and
time. Due to the non-linearity of the soot growth rate
with respect to the precursors’ concentration, the soot
mass yield decreases by a factor of two.
Laboratoire EM2C (CNRS - Ecole Centrale Paris, France) - CTR
(Stanford University, USA).
2
CERFACS, France.
3
CTR, Stanford University, USA.
The objective of this study is to evaluate the LES
approach for the prediction of soot production in an
experimental swirl-stabilized non-premixed ethylene/air
aero-engine combustor, for which soot and flame data
are available. Three simulations are performed using a
two-equation soot model to compare the performance of
a skeletal kinetic, a hybrid chemical description
(reduced chemistry for the flame structure/tabulated
chemistry for soot precursor chemistry) and a classical
tabulation
method.
Discrepancies
for
soot
concentrations between the three LES calculations will
be analyzed and the sensitivity to chemical models will
be investigated.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 46 CP1: Soot PDF modelling of soot emissions
CP1 (2/2)
M. Schiener and R. Lindstedt
The present work investigates the prediction of soot in
the Delft/Adelaide turbulent natural gas diffusion flame.
A transported pdf approach, closed at the joint-scalar
level, is used in conjunction with a second moment
solution for the velocity field and coupled with the
method of moments for modelling soot coagulation and
agglomeration. Soot oxidation via reactions with O, OH
and O2 is taken into account, and the inclusion of
surface reactions based on a second ring PAH analogy
is investigated. A parametric study of the surface
chemistry growth model is conducted and results are
compared to previous experimental and numerical data.
RANS-based modeling and uncertainty
quantification of soot formation in flames
H. Koo1, M. Mueller2, V. Raman3 and B. Dally4
1
University of Texas, USA.
4
University of Adelaide, Australia.
2
Heterogeneous PAH dimerization as an important
contributor to soot nucleation
N. Eaves1, S. Dworkin2 and M. Thomson1
1
2
University of Toronto, Canada.
Ryerson University, Canada.
Given the upcoming EURO 6 regulations, which
include limits on particle number density, soot models
must be capable of accurately predicting soot particle
sizes. In recent work [N. Eaves et al., Proc. Comb. Inst.
2015], a fundamental model for both the nucleation and
condensation processes that directly accounted for their
reversibility was developed. The model has been
modified to allow nucleation and condensation to occur
from PAHs as small as naphthalene and as large as
benzo[a]pyrene. Preliminary results demonstrate
heterogeneous dimers containing a small and a large
PAH represent the largest contribution to net soot
nucleation rates.
3
The simulation of turbulent sooting flames poses a
tremendous modeling challenge due to the complex
interaction between soot chemistry, particle dynamics,
and the background turbulent flame. Recently, highfidelity experimental data of canonical sooting flames
has been made available by the University of Adelaide.
In this work, Reynolds-averaged Navier Stokes (RANS)
simulation of this flow configuration with detailed
chemistry and soot models are presented. In any
turbulent flow simulation, a number of model
coefficients are used in the sub-models to describe the
participating physics. These model coefficients are
determined from other canonical flows and are subject
to large uncertainties. In order to better judge the
simulation capabilities, the RANS computations are
combined with a sampling-based uncertainty
quantification (UQ) approach. Variations in model
coefficients that determine turbulence properties, inflow
conditions, and soot and combustion models are
considered. The results are then compared with
experimental data to better understand the performance
and failings of the model. Overall, soot volume fraction
is predicted lower compared to experiments, and the
shape of the jet spread (controlled by turbulence model
parameters) has an important role in determining soot
evolution.
Modeling the soot particle size distribution in flames
using an extended quadrature method of moments
approach
S. Salenbauch1, A. Cuoci2, T. Faravelli2 and C. Hasse1
1
2
TU Bergakademie Freiberg, Germany.
Moment methods are an efficient and accurate approach
to model the soot evolution in flames. However, as a
drawback, the fully resolved particle size distribution is
usually not available. In this study, the recently
developed 'Extended Quadrature Method of Moments
[1]', which allows the reconstruction of the size
distribution out of a few moments, is applied to a
detailed, phenomenological soot model [2]. Retaining
the numerical efficiency of a moment approach, the
method enables a very accurate closure of the moment
source terms. Finally, the model is extended to a
bivariate description, which accounts for primary
particles and aggregates.
[1] C. Yuan, F. Laurent, R. Fox, Journal of Aerosol Science 51 (2012)
1-23.
[2] J. Appel, H. Bockhorn, M. Frenklach, Combustion and Flame 121
(2000) 122 - 136
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP1: Soot 47 Modeling soot formation and oxidation in laminar
premixed flames using the method of moments and a
continuous reconstruction of the soot number
density function
1
2
2
3
A. Wick , T. Nguyen , F. Laurent-Nègre , M. Massot ,
R. Fox4 and H. Pitsch5
1
Germany.
2
CNRS, UPR 288, Laboratoire EM2C, France; Ecole Centrale Paris,
France; CNRS, FR 3487, Fédération de Mathématiques de l'Ecole
Centrale Paris, France.
3
Laboratoire EM2C, CNRS and Ecole Centrale Paris, France; CNRS,
Fédération de Mathématiques de l'Ecole Centrale Paris, France.
4
Department of Chemical and Biological Engineering, Iowa State
University, USA; CNRS, UPR 288, Laboratoire EM2C, France; Ecole
Centrale Paris, France; CNRS, FR 3487, Fédération de
Mathématiques de l'Ecole Centrale Paris, France.
5
Germany.
Quadrature-based moment methods have shown to give
a high accuracy for the solution of the Population
Balance Equation for several processes of engineering
interest including the formation of soot. Formally, the
quadrature is equivalent to a representation of the
Number Density Function by a series of delta functions.
In case of particle disappearance due to oxidation, the
flux of particles at minimum size needs to be known,
which requires the reconstruction of the Number
Density Function by a continuous function or a
superposition of continuous kernel functions. Such
methods have recently been developed, and are now for
the first time applied and evaluated in the context of
soot formation and oxidation.
An efficient operator splitting Monte Carlo for
aerosol dynamics simulation with application to soot
formation
A. Abdelgadir1, K. Zhou2 and F. Bisetti1
1
Clean Combustion Research Center, King Abdullah University of
Science and Technology, Saudi Arabia.
2
Wuhan University of Science and Technology, Wuhan, China.
A highly efficient Monte Carlo scheme is developed for
aerosol dynamics simulation. The method accounts for
nucleation, growth and coagulation and has applications
in aerosol dynamics and combustion (soot formation).
It adopts an operator splitting technique to separate
coagulation from other processes. A careful study of the
errors and convergence properties is conducted using
forms of the collision kernel for which the analytical
solutions of the extended Smoluchowski equation are
available. The method is applied to the simulation of
soot in a laboratory flame and the results are in good
agreement with the results obtained using method of
moment.
Development of a unique function for soot surface
reactivity while oxidation and surface growth in
laminar diffusion flames
A. Khosousi and S. Dworkin
Numerical modelling of laminar coflow diffusion
ethylene/air flames is performed using complex
chemistry, detailed transport and sectional soot models.
A newly developed surface character model accounts
for soot surface reactivity in oxidation and surface
growth by considering soot aging and its effects on the
particle surface. It has been shown that soot particles
become less reactive as they age. This new development
eliminates one parameter used in soot numerical
simulations, α, and is implemented using temperature
and residence time. The model has proven reasonably
capable of predicting soot concentrations in a wide
range of laminar flames.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 48 CP2: Numerical methods CP2: Numerical methods
CP2 (1/2)
Adaptation in time and space for multi-scale
combustion fronts with error control based on
operator splitting and multiresolution
Simple and fast integration method for stiff chemical
kinetic ODEs
1
2
3
Y. Morii , H. Terashima , M. Koshi , T. Shimizu
and E. Shima1
M. Duarte1, S. Descombes2, M. Massot3, C. Tenaud4
and S. Candel5
1
1
Japan Aerospace Exploration Agency, Japan.
2
University of Tokyo, Japan.
3
Yokohama National University, Japan.
The simple and fast explicit time integration method for
stiff chemical kinetic ordinary differential equations is
proposed. Numerical simulations of ignition problems
using the proposed method are performed, and the
speed and accuracy of the proposed method are
investigated for comparison with earlier explicit time
integration method, MTS and CHEMEQ2. As a result,
the proposed method shows the superior performance to
the other explicit methods.
Physics-based preconditioning and dual
timestepping for stiff combustion problems with
detailed chemical mechanisms
1
CCSE, Lawrence Berkeley National Laboratory, USA
Laboratoire J.A. Dieudonné, CNRS and Université de Nice - Sophia
Antipolis, France.
3
4
LIMSI, CNRS, France.
5
2
We introduce a new resolution strategy for multi-scale
reaction waves based on time operator splitting and
space adaptive multiresolution. Based on theoretical
numerical analysis studies, this strategy leads to a
splitting time step which is not restricted neither by fast
scales in the source term nor by restrictive stability
limits of diffusive or convective steps, but only by the
physics of the phenomenon and can be dynamically
adapted using a posteriori error estimates. The main
goal is then to perform computationally efficient as well
as accurate in time and space simulations of the
complete dynamics of multi-scale phenomena.
M. Hansen and J. Sutherland
Detailed simulation of turbulent, low-Mach combustion
is difficult due to the breadth of length and time scales
involved. A principal difficulty of combustion is
stiffness due to strong coupling between 'slow'
processes such as convection and mixing and 'fast'
processes such as ignition and equilibration. The
inherent stiffness and nonlinearity of detailed chemical
mechanisms severely constrain traditional integration
methods. Matrix preconditioning is a versatile
acceleration technique which has seen little
development for combustion. We present results that
demonstrate the efficiency of dual time-stepping and a
novel preconditioning approach in resolving lowfrequency physics of stiff, 0-D reactors with detailed
chemical mechanisms.
A new approach to secure scalar boundedness in
flame simulation with high-order spectral difference
methods on unstructured meshes
E. Bossennec, G. Lodato, P. Domingo and L. Vervisch
In flame simulation, it is essential to preserve scalar
boundedness. Various approaches exist to do so, but
none is actually fully satisfactory (clipping, additional
diffusivity, etc.). In the proposed approach, a scalar
discontinuity sensor is obtained from the modal
decomposition of the signal within every cell, in the
context of spectral difference (SD) methods. The
objective of SD is to secure a given degree of accuracy,
whatever the mesh topology and stretching. From the
modal decomposition of the scalar signal, an autocalibration of an additional dissipative term is designed
within every cell element and various tests cases are
discussed.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP2: Numerical methods G-equation based modelling of partially premixed
compressible reactive flows
L. Gastaldo and J. Latché
IRSN, France.
We present a model and a numerical scheme for the
simulation of partially premixed compressible reactive
flows, implemented in the IRSN software P2REMICS.
The flame brush location is determined by a level-setlike equation, the so-called G-equation. To cope with
partially premixed situations, the species mass balances
are however solved, but with a reaction rate depending
on the level-set function. This system is solved by a
fractional-step algorithm, which ensures the essential
stability properties, like keeping the species mass
fractions or thermodynamic variables (pressure, internal
energy) within their physical bounds. The simulation of
a free hydrogen jet explosion is presented.
Modelling of flame lift-off evolution: numerical
implementation of density-pressure coupling
Z. Chen, S. Ruan and N. Swaminathan
Three-dimensional unsteady simulations of turbulent
lifted methane/air jet flames are performed to
investigate transient evolution of flame lift-off process.
Premixed flamelets based partially premixed
combustion modelling framework is implemented using
the OpenFOAM CFD platform. The implementation
effects of using different density-pressure coupling
approaches on the temporal and spatial evolution of the
most upstream point of flame leading edge are studied.
It is found that the final flame lift-off height is
influenced only marginally by these effects, whereas a
highly coupled density-pressure solving approach is
required to capture the transient propagation process of
flame lift-off evolution.
CP2 (2/2)
High-order CENO finite volume scheme for largeeddy simulation of turbulent reactive flows
L. Tobaldini Neto and C. Groth
University of Toronto, Institute for Aerospace Studies, Canada.
A novel, parallel, high-order, central essentially nonoscillatory (CENO), finite-volume scheme is proposed
for large-eddy simulation (LES) of turbulent reactive
flows. The high-order CENO finite-volume scheme is
applied to the solution of the Favre-filtered NavierStokes equations governing a fully-compressible
49 reactive mixture on multi-block, body-fitted,
computational mesh consisting of hexahedral elements.
The CENO method uses a hybrid reconstruction
approach based on a fixed central stencil that avoids the
complexities of other ENO schemes and offers several
computational advantages.
Numerical results are
discussed for laboratory-scale turbulent premixed
methane-air flames and the performance of the highorder approach relative to standard lower-order schemes
is assessed.
LES simulation of reactive flow with effective PDF
models at a minimal cost
Y. Ge, F. Ferraro and M. Pfitzner
der Universität der Bundeswehr München, Germany.
LES is gradually becoming a reliable design tool in
computational fluid dynamics. However, in combustion
CFD, chemical reactions and their interaction with
turbulence are also important. Advanced PDF methods
have been proved to work well in non-premixed
combustion. In a Lagrangian implementation, the
computational cost is linked to the number of particles
involved. Two methods are presented to incorporate the
PDF model into the LES simulation at a minimal cost.
The sparse-Lagrangian simulation requires less Pope
particles than the LES grid cells while a hybrid
LES/RANS-PDF simulation performs the PDF
calculation within RANS context using an averaged
LES flow field.
Large eddy simulation using adaptive mesh
refinement with a multi-level subgrid scaled closure
for turbulent reacting flows
B. Muralidharan and S. Menon
Georgia Institute of Technology, USA.
We employ a new strategy to use adaptive mesh
refinement (AMR) within a LES to couple the largescale features resolved on AMR grid with a subgrid
turbulence-chemistry linear-eddy mixing (LEM) model.
Unlike conventional past implementation of LEM
within a fixed grid LES, in this hierarchical scheme the
subgrid closure for turbulence and for turbulencechemistry occur on independent grids that exploit the
strengths of each approach. Application to turbulent
Hydrogen/Air reacting jet in cross flow (JICF) show
that features such as lifted flame structure and triple
flame formation are captured in good agreement with
low Re DNS. More comparisons with high-Re
experiments of reacting H2/AIR JICF will be shown in
the final presentation.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 50 CP2: Numerical methods Development, validation and application of a DNS
approach for heterogeneous reactive flows
1
2
2
3
A. Chabane , K. Truffin , A. Nicolle , F. Nicoud and C.
Angelberger2
1
IFPEN/ECP, France.
IFPEN, France.
3
Université Montpellier 2, France.
Compressible mixing of liquid fuels
A. Hernandez1, S. Stekovic1, D. Stewart2 and A. Wass1
1
Mechanical Science and Engineering, University of Illinois at
Urbana-Champaign, USA.
2
no affiliation
2
Appropriate boundary conditions accounting for mass,
momentum and heat transfers near a reactive wall are
derived for the Direct Numerical Simulation of
heterogeneous reactive flows. A specifically developed
implicit solver for the resolution of detailed surface and
gas-phase chemistry is coupled with the explicit
LES/DNS code AVBP. The numerical developments
are validated using analytical solutions and academic
configurations for which experimental data are
available. The impact of heterogeneous reactions and
obstacles on transfers near a catalytic surface, on a
catalytically-stabilized reaction zone and on pollutant
conversion kinetics are studied for the case of a
channel-flow monolithic catalyst.
We present a multidimensional combustion model for
high pressure, compressible mixing of liquid fuels that
vaporize and mix with entrained air to burn. A robust
multi-component, fully parallel, finite difference code
was developed to solve these three-dimensional
complex reactive flow problems. The spatial component
of the governing equations is solved by a positive
preserving WENO interpolation solver and the temporal
component uses a TVD Runge-Kutta scheme. For
reflective boundary conditions we developed a
simplified novel point-wise level set scheme that is
local and can efficiently run on parallel machines.
Computed results show good agreement between
numerical and experiment data.
CP3: Kinetics reduction and tabulation
CP3 (1/3)
Extraction of Chemical kinetics insights
with special CSP data
S. Lam
In order to claim insights on a massively complex
chemical reaction system, one needs answers to the
following questions: (1) What are the current time
scales of the reactions? (2) Which reactions are
currently rate-controlling? (3) Which chemical species
and which chemical reactions included in the full
chemistry model are currently unimportant? (4) What
simplified-chemistry models could honor a userspecified species-by-species error tolerance? (5) What
happens to the above answers if some of the parameters
were changed? This paper shows how to
computationally obtain insightful and definitive answers
to such questions by exploiting reaction-specific special
CSP data (S. Lam, Combustion and Flame, 2014).
Reduction of chemical mechanisms for aviation fuels
with RCCE
W. Jones, P. Koniavitis and S. Rigopoulos
Department of Mechanical Engineering, Imperial College London,
UK.
Detailed mechanisms for aviation fuels contain
hundreds of species and thousands of reactions,
indicating a necessity for reduced mechanisms. RateControlled Constrained Equilibrium (RCCE) provides a
physical and mathematical framework for deriving
reduced mechanisms, where the kinetically controlled
(slow) species are determined from the kinetics of the
detailed mechanism, while the equilibrated (fast or
steady-state) species are calculated by minimising the
Gibbs free energy of the system. In this work, we derive
reduced chemical mechanisms with RCCE for kerosene.
Several sets of constraints and surrogate fuels are
employed, and a considerable degree of reduction is
obtained.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP3: Kinetics reduction and tabulation 51 Investigation of corrugated premixed methane-air
flame structure using REDIM
Trivariate chemistry model for the simulation of
high Karlovitz premixed turbulent flames
A. Neagos, V. Bykov and U. Maas
B. Savard and G. Blanquart
The correct description of transient turbulent processes
within thickened and corrugated flames represents a
challenging problem for model reduction. In the present
study the performance of the REDIM model reduction
in such flame scenarios is investigated. Therefore an
examination of the relaxation process of perturbed 1D
premixed methane-air flames is carried out.
Perturbations are implemented via triplet maps leading
to corrugated flame structures. Among other
investigation a comparison of detailed and reduced
calculations regarding relaxation time scales dependent
on size and magnitude of the triplet perturbation is
performed. It is shown that the reduced models (1D and
2D) can capture such critical transient flame behavior
for different equivalence ratios.
A trivariate chemistry model is proposed to capture
accurately the chemical source term fluctuations of
thermodiffusively-stable premixed turbulent flames in
the thin/broken reaction zones regimes. The model is
derived mathematically from a local coordinate
transformation. A progress variable, its dissipation rate,
and the curvature of its isosurfaces are used to represent
the chemical state through a flamelet-generated
manifold. This manifold is first validated using direct
numerical simulations of turbulent flames with detailed
chemistry. The model, which requires a single scalar
transport equation, is then used to simulate these
flames. The model can predict most of the flames'
characteristics at a significantly lower computational
cost.
Flamelet/Progress Variable CFD Modeling of HighPressure Partial Oxidation Flame
CP3 (2/3)
M. Vascellari, H. Xu, S. Hartl and C. Hasse
In partial oxidation processes two significant reactions
regimes can be observed. In the flame zone, the fast
oxidation reactions are mainly governed by the mixing
of the fuel with the reactants, similarly to conventional
lean diffusion flames. In the post-flame zone, the
reforming reactions takes place, slowly approaching to
the chemical equilibrium conditions.
In order to describe both regimes, the flamelet/progress
variable (FPV) approach was successfully applied to
model a pilot-scale High-Pressure Partial OXidation
(HP-POX) reactor fired with CH4 and O2/H2O,
respectively. The chemistry was pre-computed using
laminar one-dimensional premixed freely propagating
flames in physical space for different mixture fractions
and stored in a look-up table. Turbulent fluctuations
were accounted by means of the PDF-averaging of the
laminar solution in flamelet and progress variable
spaces. The laminar solutions were converted from
physical space to a progress variable (PV) space, which
was defined combining different chemical species in
order to have a monotonically growing function.
Additionally, the PV should be accurately defined for
resolving the slow reactions in the post-flame zone.
Finally, the PDF look-up table generated was coupled to
the CFD solution of the turbulent flow in the HP-POX
reactor. The numerical results shows that the FPV
allows to describe both the fast oxidation and the slow
reforming reactions, giving a reasonable agreement with
the experiments.
A reduced and optimized chemical mechanism for ndodecane oxidation
L. Cai, L. Kröger and H. Pitsch
Germany.
A strongly reduced kinetic mechanism for n-dodecane
oxidation will be presented. The mechanism consists of
around 60 species and is quite compact in comparison
with mechanisms in the published literature. For
improved model performance, the reduced n-dodecane
mechanism is further automatically optimized against a
large number of experimental measurements over a
variety of conditions. The resulting mechanism is
compared with detailed and other reduced mechanisms
in the literature to assess model performance in
predictions of combustion properties and engine
simulations. The reduced mechanism presented here is
shown to be quite accurate and besides other quantities
also reproduces burning velocities very accurately.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 52 CP3: Kinetics reduction and tabulation Reduced schemes in combustion
1
1
1
A. Felden , B. Cuenot , E. Riber and P. Pepiot
2
1
CERFACS, Toulouse, France.
Sibley School of mechanical and Aerospace Engineering, Cornell
University, USA.
2
Recent progress in CFD applied to complex combustion
systems, coupled to the increase in available
computational power, now allows for the use of a more
accurate chemistry description through reduced kinetic
schemes. Derived in a fast and efficient way, such
schemes greatly improve flame predictions at a
reasonable cost.
The methodology and available tools for their
derivation will be presented first, followed by a
demonstration of their performances in terms of
accuracy and CPU cost for the combustion of various
hydrocarbons. Finally, a LES of a realistic combustion
chamber using the obtained reduced kinetic schemes is
performed and analyzed. In particular, the potential for
increased prediction capability of such simulations is
discussed.
Using genetic algorithms for optimizing reduced
chemical-scheme for turbulent flames simulation
N. Jaouen, P. Domingo and L. Vervisch
quality of it depends heavily on the choice of the mass
fraction. A regularization method is applied to select
strain parameters, which are optimal with respect to
different sets of constraints. The resulting
parameterizations are tested in large-eddy simulations
of a turbulent premixed jet burner and the sensitivities
of the results are assessed.
Using large eddy simulation (LES) for pollutant
prediction in turbulent flames.
T. Jaravel, E. Riber and B. Cuenot
CERFACS, France.
The accurate prediction of pollutants emitted by
combustion systems remains a challenge due to the
complexity of the involved chemistry and flow. To
describe pollutant chemistry, an analytically reduced
mechanism for methane-air oxidation, including carbon
monoxide (CO) and nitrogen oxide (NOx) is proposed.
This mechanism is first evaluated on laminar flames,
showing a good prediction capability for both CO and
NOx. It is then combined to LES to compute the Sandia
D turbulent diffusion flame. Results are found in good
agreement with measurements in terms of flame
properties and pollutant formation. Effects of grid
resolution and reduced chemical scheme are also
discussed.
A strategy to optimize reduced chemical schemes based
on a genetic algorithm is discussed. The targets of the
optimization procedure are the chemical source profiles
of a reduced number of species. These reference
chemical sources are reconstructed from a detailed
chemical scheme, so that the balance equations of the
reduced number of species are closed when imposing
the profiles obtained with detailed chemistry and for
given transport properties. The optimization is first
performed for H2/Air combustion, to then add the
necessary reactions to simulate CH4/Air premixed
flames at various equivalence ratios.
Application of a regularization method to the choice
of the strain parameter in LES of a turbulent
premixed jet burner
K. Kleinheinz1, E. Knudsen2, E. Hawkes3 and H. Pitsch1
1
Institut for Combustion Technology, RWTH Aachen University,
Germany.
2
Dept. of Mechanical Engineering, Stanford University, USA.
3
Faculty of Engineering, The University of New South Wales,
Australia.
An adaptive strategy for the efficient
implementation of complex chemistry in turbulent
flame simulations
Y. Liang, S. Pope and P. Pepiot
Cornell University, USA.
The integration of detailed chemical kinetics for
practical fuels in turbulent combustion simulations is in
most cases prohibitive in terms of computational cost.
We will describe an adaptive strategy tailored for
LES/particle PDF simulations of turbulent flames that
relies on an a priori partition of the composition space
into a specified number of regions, over which suitable
reduced chemical mechanisms are identified prior to the
simulation. The method is combined in LES/PDF with
In-Situ Adaptive Tabulation (ISAT) and reduced
computational particle representations to show
significant gain, both in terms of memory and CPU
usage.
A strained flamelet model has recently been proposed,
which accounts for turbulence’s perturbations of the
flame structure. Its novelty is the strain
parameterization via a species mass fraction. The
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP3: Kinetics reduction and tabulation CP3 (3/3)
th
Reducing chemistry table sizes by using
polynomial functions
W. Leudesdorff, A. Ketelheun and J. Janicka
Energy and Power Plant Technology, TU Darmstadt, Germany.
Flamelet generated manifolds are well-established in
large eddy simulations of combustion processes.
However, the tables tend to get very large due to the
required resolution and to ensure an efficient searchfree access during the simulation and thus occupy much
memory in parallel computations. With an increasing
number of control variables, this problem gets worse.
Within this work, a method was developed to avoid the
fine equidistant tabulation by using polynomial
functions to represent the variables’ dependencies
especially on the mixture fraction. The results show a
significant reduction in required memory by
maintaining the accuracy of the chemistry
representation.
From fully premixed to highly stratified combustion
using hybrid transported tabulated chemistry
B. Duboc, G. Ribert and P. Domingo
CORIA-Normandy University, France.
A novel way to downsize detailed chemistry, HTTC,
has been recently proposed by Ribert et al. (FTaC
2014). In that method, the major species are transported
while the intermediate species are tabulated, making use
of their self-similarity properties.
In the present work, the capacities of HTTC to handle
combustion regimes from fully premixed to highly
stratified flames, up to the limit of diffusion flames, are
explored. The performances of HTTC will be compared
toward fully detailed chemistry and classic tabulated
chemistry approaches. The numerical set-up consists in
a V-flame, fed by a flow featuring various gradients of
equivalence ratio.
Comparative analysis of kinetic mechanism
reduction methods within the tabulation of dynamic
adaptive chemistry framework
F. Contino1, T. Lucchini2, S. Backaert3, N. Bourgeois3,
A. Parente4 and H. Jeanmart3
1
Vrije Universiteit Brussel, Belgium.
3
Université catholique de Louvain, Belgium.
4
Université Libre de Bruxelles, Belgium.
2
53 simulations, many methods reduce the size of these
mechanisms to the set of species and reactions needed
for the specific thermal-chemical conditions of the case
being investigated. In the context of on-the-fly
reduction coupled to a dynamic tabulation technique,
the size of the mechanism changes during the
simulation which has a great impact on the coupling.
We compare the efficiency of five different reduction
methods in the framework of the TDAC method. This
paper presents the most effective reduction techniques
for two test cases: an inhomogeneous auto-ignition case
and an unsteady flame in a closed vessel.
Principal component transport in turbulent
combustion
T. Echekki and H. Mirgolbabaei
North Carolina State University, USA.
The solution of turbulent combustion problems based
on the transport of principal components (PCs) is
demonstrated. The PCs are derived from a priori
principal component analysis (PCA) of computational
data. This analysis is used to construct and tabulate the
PCs’ chemical source terms and diffusion coefficients
in terms of the PCs using artificial neural networks
(ANN). The a posteriori validation is implemented on
different combustion problems and yields a very good
reconstruction of the original thermo-chemical scalars
profiles with a significant reduction in the number of
transported variables.
Principal component analysis for modelling
turbulent premixed flames
A. Coussement1, O. Gicquel2, B. Isaac3 and A. Parente1
1
Université Libre de Bruxelles, ATM Department, Belgium.
3
University of Utah, Department of Chemical Engineering, USA.
2
In the last years the potential of principal component
analysis for the development of reduced order turbulent
combustion models has been investigated. Recently, a
few methods have been able to perform a posteriori
computations, but no comparative analysis has yet been
performed. This work aims at filling this gap by
presenting a comprehensive comparison between the
MG-PCA and Score-PCA technique for laminar and
turbulent premixed flames. Computations are done
using direct numerical simulations to consider only the
quality of the combustion modelling. Finally, special
care is also applied to the treatment of differential
diffusion including further developments of Score-PCA.
To mitigate the impact of large chemical kinetic
mechanism on the computational time of CFD
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 54 CP4: Internal combustion engines CP4: Internal combustion engines
Assessment of double conditioning of reactive scalar
transport equations for HCCI
1
2
1
Investigations on pressure wave generation and
chemical kinetics during end-gas autoignition on
knocking combustion
3
F. Salehi , M. Talei , E. Hawkes , A. Bhagatwala , J.
Chen3 and S. Kook1
H. Terashima1 and M. Koshi2
1
The University of New South Wales, Australia.
2
The University of Melbourne, Australia.
3
1
This work investigates doubly conditional moment
closure (CMC) equations under HCCI conditions. For
this purpose, a set of direct numerical simulation (DNS)
data is used. In the DNS cases, ignition of a lean
ethanol/air mixture with thermal inhomogeneities is
simulated. Two possible variables including scalar
dissipation and progress variable are introduced as a
second conditioning variable into the first-order CMC
model. A priori test using DNS data shows that the
choice of progress variable significantly improved
results compared to the choice of scalar dissipation
however the former leads to more difficulties in
modelling the joint PDF and the cross dissipation rate.
A knocking combustion modeled using a onedimensional constant volume reactor is simulated in a
manner of direct numerical simulations, in which large
detailed chemical kinetic mechanisms for two premised
gases, n-butane (113 species) and n-heptane (373
species), are directly and efficiently used with the
compressible Navier-Stokes equations. Detailed
mechanisms of pressure wave generation and chemical
kinetics during end-gas autoignition are discussed,
which would lead to an explanation of super-knocking
combustion. The study would also discuss the effects of
wall temperature conditions on the strength of knocking
combustion.
A DNS study of ignition characteristics of a lean
H2/air mixture under HCCI conditions within an
enclosed geometry including wall heat transfer
M. Bolla1, M. Schmitt2, E. Hawkes1 and K. Boulouchos2
2
University of Tokyo, Japan
Prediction of super-knock in a downsized sparkignition engine using Large-Eddy Simulation
K. Truffin, A. Robert, O. Colin and C. Angelberger
IFPEN, France.
1
2
Swiss Federal Institute of Technology, Switzerland.
This work presents results from a two-dimensional (2D)
direct numerical simulation (DNS) of a lean H2/air
mixture under homogeneous charge compression
ignition conditions within an enclosed geometry
including wall heat transfer. Initial and boundary
conditions have been taken from a previous nonreacting DNS [Schmitt et al., Proc. Comb. Inst. 35
(2015) 3069-3077] in an engine-like geometry. The
domain consists of a rectangular 2D slice (75mm x
7.5mm). The initial H2-air mixture is compositionally
homogeneous and is thermally stratified according to
the compression stroke history. The DNS are analysed
to understand the effects of the wall on the ignition
behaviour.
Downsizing is a major pathway to improve the fuel
efficiency and reduce CO2 emissions from Spark
Ignition Engines (SIE). Its principle is to increase the
specific load at which the engine is operated. The
resulting thermodynamic conditions inside the cylinder
however tend to favour the appearance of uncontrolled
auto-ignition and can result in the onset of detonation.
They are therefore very complex to study
experimentally due to the risks of engine damage. The
fundamental novelty of the proposed research is to
develop and validate LES approaches for studying such
soliton cycles and quantifying the probability for their
occurrence.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP4: Internal combustion engines Towards an integrated approach to realistic engine
modeling with large-scale computing
S. Aithal
Predicting the performance and emissions of
automotive engines over a wide-range of operating
conditions is a daunting task. High-fidelity simulations
can provide details of the flow physics but the required
computational effort precludes their use for parametric
55 studies. Reduced-order models can be used for largescale parametric sweeps but require tuned parameters
for realistic results. An integrated approach to realistic
engine modeling combines the unique features of both
the high-fidelity simulations with reduced-order
simulations. This work describes the development of a
framework to conduct large-scale simulations using
such an integrated approach.
CP5: Turbulent combustion
CP5 (1/6)
Modelling of the subgrid scale wrinkling factor for
large-eddy simulation of
turbulent premixed combustion
F. Thiesset1, G. Maurice1, F. Halter1, N. Mazellier2, C.
Chauveau1 and I. Gökalp1
1
2
ICARE, CNRS Orléans, France.
PRISME, Univ. Orléans, France.
We propose a model for assessing the unresolved
wrinkling factor in LES of turbulent premixed
combustion. It relies on a power-law dependence of the
wrinkling factor to the filter size and an original
expression for the ’active’ corrugating strain rate. The
latter is written as a product of a new efficiency
function by a recent expression for the turbulent strain
intensity. Yields functional expressions for the fractal
dimension and the inner cut-off length scale, the latter
being (i) filter-size independent and (ii) consistent with
the Damköhler asymptotic behaviours at both large and
small Karlovitz numbers. A new expression for the
wrinkling factor which incorporates finite Reynolds
numbers effects is also proposed.
sub-grid wrinkling. However, if the TFM
transformation is applied to the complete Navier-Stokes
equations, the effect of sub-grid wrinkling can be
directly captured. Two sets of simulations will be
presented and compared with experimental data. The
effects of TFM on the scalar equation and in the full
Navier-Stokes equations will be investigated.
Analysis of a dynamic flame wrinkling factor model
for large eddy simulations of
turbulent premixed combustion
P. Stefanin-Volpiani, T. Schmitt and D. Veynante
Dynamic models where model parameters are
automatically adjusted from known resolved fields are a
very attractive formulation for large eddy simulations.
Now widely used for unresolved momentum transport,
this approach remains rather marginal to describe
filtered reaction rates despite of very promising results.
The influence of physical (flame wrinkling inner cut-off
length scale) and numerical (test filter width, averaging
procedure, filtering frequency, …) characteristics of a
flame wrinkling factor dynamic model for turbulent
premixed combustion is investigated. Numerical results
are discussed in terms of mean flow fields as well as
dynamical behaviors.
Modelling of lean premixed flames based on a new
artificial thickened flame framework
K. Vogiatzaki1, S. Navarro-Martinez2, S. Hong3,
S. Shanbhogue3 and A. Ghoniem3
A dynamic sub-grid model for turbulent combustion
based on conditional averaging
G. Hendra, M. Salehi and W. Bushe
1
City University, London, UK.
2
Imperial college London, UK.
3
MIT, USA.
In this work we present a numerical investigation of
lean premixed flames behaviour at a backward-facing
step combustor with a modified version of the
Thickened Flame Model (TFM). In conventional TFM
approach, an efficiency function is used to represent the
University of British Columbia, Canada.
The Germano dynamic sub-grid model in Large Eddy
Simulation requires averaging of turbulence parameters
across ensembles of statistical homogeneity. We
propose that binning by mixture fraction (a proxy for
instantaneous position within the mixing layer) could
provide more accurate results than the traditional
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 56 CP5: Turbulent combustion approach of binning by radius (a proxy for average
position). Properly accounting for sub-grid variation in
mixture fraction requires inversion of an integral
expression; the method therefore has a natural synergy
with the Conditional Source-Term Estimation (CSE)
closure for the chemical source term in turbulent
reacting flows, which calculates conditional averages of
progress variables by integral inversion.
Large eddy simulation of turbulent combustion with
a dynamic second-order moment closure model
K. Luo, J. Yang, Y. Bai and J. Fan
Zhejiang University, China.
A new dynamic second-order moment closure (DSMC)
model is developed for large eddy simulation of
turbulent combustion. The averaged reaction rate is
directly closed in the form of Arrhenius law. The thirdorder fluctuation correlations are neglected, and the
second-order fluctuation correlations are closed using
the algebraic form. All the coefficients in the model are
evaluated dynamically. A-priori validation using a DNS
database and a-posteriori validation by LES of Sandia
Flame D are performed. The results show the capacity
of the new model to capture different flame regions and
the efficiency to predict turbulent combustion.
A dynamically adaptive combustion framework for
the general description of complex flame
configurations
H. Wu, Y. See, Q. Wang and M. Ihme
A new combustion modeling framework is developed to
dynamically adapt the local fidelity of the combustion
model for reacting flows by combining a hierarchy of
combustion models with different fidelity. The
adaptation is achieved by dynamically assigning a
combustion model under consideration of their accuracy
and computational cost. The usage of each model is
confined to the trust region whose size is specified by
the user. The choice of combustion model is determined
adaptively such that lower dimension manifold is used
when it is deemed sufficiently accurate. To achieve this,
a manifold assessment method for chemistry is utilized
to estimate the model prediction accuracy of a given
quantity of interest. This fidelity-adaptive model is
applied to a triple flame to demonstrate its capability
and the model performance is assessed through direct
comparisons against a detailed numerical simulation.
CP5 (2/6)
Spectral model of premixed turbulent flame
S. Rashkovskiy
Institute for Problems in Mechanics of the Russian Academy of
Sciences, Russia.
We consider the hierarchical model of premixed
turbulent flame and derive an equation which describes
the propagation of curved premixed flame front in
turbulent flow. We show that in space of wavenumber
of flame disturbances it is possible to formulate the
Cauchy problem and calculate the structure of turbulent
premixed flame and its propagation velocity. We
discuss the numerical method of solution of obtained
equation and compare the results of simulation with
some analytical solutions of this equation.
Analysis of approximate deconvolution strategies
and explicit filtering for LES of turbulent flames
P. Domingo and L. Vervisch
Large eddy simulation of turbulent combustion using
approximate deconvolution and explicit flame filtering
is further discussed. In this approach, the closure of the
unresolved non-linear terms relies on the explicit
filtering of their exact expressions, computed after an
approximate deconvolution of the resolved scalars.
Various strategies may be envisioned to perform this
deconvolution, which provides and approximation of
the unresolved subgrid scale fluctuations in LES. Using
DNS of a jet flame imbedded in LES, approximate
deconvolution based on a series of approaches, as
inverse discrete filtering, analytical inverse filtering or
tabulated inverse filtering with detailed chemistry, are
examined.
Chemical source term modeling in LES of reacting
flows using deconvolution method
Q. Wang and M. Ihme
In this study, an LES model for chemical source term
using deconvolution techniques is proposed. The model
recovers the sub-grid scale scalars that are discarded by
the LES filter from the information retained in the
large-scale structures using a Wiener filter. However,
like other linear deconvolution operations being used in
literature, the Wiener filter has a limitation in
constraining the physical bound of variables. To counter
this limitation, a constrained minimum mean-square
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP5: Turbulent combustion optimization problem is solved locally. No additional
assumptions and relaxation terms are required in the
current model. Both a priori and a posteriori studies will
be conducted.
57 turbulence fluctuations in the flame front and changes
the turbulent flame thickness.
Radiative properties of molecular combustion
products and of some hydrocarbons: state of the art
The framework of multiple mapping conditioning,
its applications and prospects
A. Klimenko1, M. Cleary2, B. Sundaram1 and
L. Dialameh1
1
2
The University of Queensland, Australia.
The University of Sydney, Australia.
The framework of Multiple Mapping Conditioning
(MMC) has undergone a noticeable evolution since the
original MMC was suggested by Klimenko and Pope in
2003. The MMC approach evolved from deterministic
to stochastic and generalized formulations of the model.
In this more general interpretation, MMC is a PDF
approach that allows for enforcing a set desired
properties on mixing operations by conditioning this
operator on MMC reference variables. In this form
MMC is not a specific model but a framework
introducing a set of principles that allow us to improve
modeling through enforcing desired conditional
properties on mixing. This understanding of MMC has
resulted in a number of specific models including
sparse-Lagrangian FDF, Shadow Position Mixing
Model and MMC Partially Stirred premixed reactor. In
context of premixed flames, the MMC approach allows
for modeling of both distributed reactions and flamelet
regimes (as well as any regime in between these
limiting cases). This presentation will discuss major
features and applications of generalized MMC.
Radiation effects on a turbulent premixed
syngas flame
S. Karimkashi1, M. Bolla1, H. Wang1, E.R. Hawkes1,
H.G. Im2, P.G.. Arias2 and M. Talei3
1
School of Mechanical and Manufacturing Engineering, University of
New South Wales, Australia.
2
Clean Combustion Research Center, King Abdullah University of
Science and Technology, Saudi Arabia.
3
Department of Mechanical Engineering, University of Melbourne,
Australia.
In this study, the effect of radiation on a freely
propagating turbulent premixed syngas flame is
investigated using two-dimensional direct numerical
simulation (DNS). Both adiabatic and non-adiabatic
(with radiation) cases are examined and compared. The
radiative transfer equation (RTE) has been solved using
the discrete ordinate method (DOM) and the radiation
properties of the medium are assumed to be grey. The
DNS results demonstrate the role of radiation
absorption affecting the temperature and species
concentrations. Furthermore, radiation moderates
P. Rivière and A. Soufiani
We present in this communication the state of the art
concerning radiative properties of light molecular
species that appear either as final products or as small
hydrocarbons in combustion applications. Discussion
will start with the available up to date spectroscopic
databases and their limitations; then various
approximate models will be introduced and their
accuracy studied in the context of combustion. The last
part of the presentation will address the overlapping
between different species absorption bands in order to
highlight for instance the possibility of preheating of
fresh gases by radiation from combustion products.
CP5 (3/6)
An a priori DNS study of molecular mixing models
in a planar stationary premixed flame
X. Zhao1, H. Kolla2 and J. Chen2
1
2
University of Connecticut, USA.
A statistically stationary planar turbulent premixed
methane flame is simulated using direct numerical
simulations (DNS). The turbulent burning velocity of
the flame is calculated as a volume integral of the fuel
consumption rate across the flame, and through a
feedback loop, maintains the mean inflow velocity to
enforce stationarity. The DNS study includes parametric
variations in Damköhler number and Reynolds number.
Lagrangian tracer particles are advected along with the
flow field in order to aggregate Lagrangian statistics.
The statistics are then used to perform an a priori
assessment of molecular mixing models in the context
of transported probability density function methods.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 58 CP5: Turbulent combustion 3D DNS of methane-air turbulent premixed planar
flame in thin reaction zones
B. Yenerdag, Y. Naka, M. Shimura and M. Tanahashi
Direct numerical simulation of spontaneous flame
propagation under reactivity controlled compression
ignition conditions
A. Bhagatwala1, R. Sankaran2, S. Kokjohn3
and J. Chen1
Tokyo Institute of Technology, Japan.
Three-dimensional direct numerical simulation of
methane-air turbulent premixed planar flame
propagating in homogenous isotropic turbulence is
conducted to investigate local flame structure in thin
reaction zones. A detailed kinetic mechanism (GRIMech 3.0) which includes 53 reactive species and 325
elementary reactions is used to represent methane-air
reactions. For a better understanding of the local flame
structure in thin reaction zones, distributions of mass
fractions of major species, heat release rate and
temperature are investigated. To clarify effects of
turbulence on the local flame structure, the statistical
characteristics of flame elements are also revealed.
A peta-scale direct numerical simulation study on
pollutant formation in turbulent premixed flames
P. Trisjono and H. Pitsch
1
2
3
ORNL, USA.
University of Wisconsin, USA.
Auto-ignition and spontaneous flame propagation in a
primary reference fuel mixture consisting of n-heptane
and iso-octane at reactivity controlled compression
ignition (RCCI) conditions were studied through direct
numerical simulation. The simulations employed a
novel mass source/sink term to replicate the effects of
compression heating. The effect of temperature and fuel
concentration gradients on the combustion mode was
investigated. The effect of varying bulk temperature and
the shape of the stratification were also simulated. It
was found that higher n-heptane concentration and
higher level of thermal stratification resulted in a
greater degree of flame propagation, whereas lower nheptane concentration and higher pressure resulted in
more prevalent autoignition.
Institut für Technische Verbrennung, RWTH Aachen University,
Germany.
The development of high-fidelity modeling strategies
for pollutant formation in turbulent premixed flames is
often severely impeded by the lack of reliable data. In
this work, a new direct numerical simulation of a lean
turbulent methane-air flame at a jet Reynolds number of
Re=9000 including complex NOx and CO pollutant
formation chemistry is presented. The simulation
configuration features a temporally evolving premixed
jet flame that is discretized on almost 3 billion grid cells
and the chemistry is described by a detailed chemical
mechanism consisting of 32 species. This makes this
DNS novel with respect to the level of detail of the
interaction of turbulence and pollutant formation, and a
powerful database for the understanding and modeling
of NOx and CO. There are three objectives for the
present talk. First, the computational approach and the
numerical setup are presented. In this study, the highorder finite difference inhouse code CIAO is utilized,
which features excellent primary and secondary
conservation and scales up to 100.000 cores.
Furthermore, the quality of the DNS database is
discussed, comparing characteristic quantities of the
DNS database against canonical DNS quality criteria
and demonstrating that the presented DNS meets these
criteria. Finally, statistics of formation rates of NOx and
CO are analyzed and assessed in the context of
modeling strategies for large-eddy simulations.
Direct numerical simulation of a turbulent lifted
DME jet flame in a heated coflow
at elevated pressure
Y. Minamoto and J. Chen
Direct numerical simulation (DNS) of a threedimensional turbulent lifted dimethyl ether (DME) jet
flame in a heated coflow is performed at 5 atmospheres.
The jet Reynolds number is 11,700 and and a reduced
chemical mechanism that is comprised of 30 species is
employed to include the effects of negative temperature
coefficient and low-temperature heat release on the
flame dynamics. The near field of the jet including the
lifted flame stabilization is investigated based on flame
structure, propagation, and chemical analysis. The
interaction between premixed flame propagation into a
partially oxidized mixture of low-temperature
autoignition intermediate species and the underlying jet
coherent structures is also discussed.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP5: Turbulent combustion 59 Modal analysis of reacting jet in cross flow using
direct numerical simulations
LES combustion modelling of the dynamics of
turbulent pulsed premixed flames
T. Sayadi1, S. Lyra2, C. Hamman3, H. Kolla2,
P. Schmid4 and J. Chen2
A. Chatelier1, R. Mercier2, N. Bertier3 and B. Fiorina2
1
University of Illinois at Urbana-Champaign, USA.
2
3
Center for Turbulence Research, Stanford University, USA.
4
Department of Mathematics, Imperial College London, UK.
Three-dimensional direct numerical simulations of a
turbulent transverse jet in cross flow (JICF) are
performed in order to study the influence of heat release
on the jet shear layer instability. The numerical
simulations consist of a H2/He jet of Reynolds number
2420, in vitiated cross-flow of methane combustion
products, at a channel Reynolds number of 9840. The
dominant modes of the system are then extracted using
Dynamic Mode Decomposition (DMD). The DMD
algorithm employs a parallel QR-factorization, which is
further used as a basis of the underlying parallel SVD
leading to the modal decomposition. The resulting
parallel algorithm scales well on machines with a large
number of processors and, therefore, allows the
decomposition of very large data-sets (4.7 billion grid
points).
1
ONERA / EM2C, France.
3
ONERA, France.
2
This work presents numerical investigations of
turbulent flame dynamics. The simulations use a recent
formulation of the model F-TACLES (Filtered
TAbulated Chemistry for LES) to address flame front
resolution issues. For that purpose, two filter sizes
associated to the flow and the flame front, respectively,
are introduced in the filtered progress variable balance
equation. This new formalism designed to improve
resolved flame turbulence interactions, is tested on a
pulsed swirled flame stabilized in a non-adiabatic
confined combustor. Comparison between experimental
measurement and numerical prediction of flame transfer
functions is presented.
DNS of high turbulence intensity premixed methane-air
flames in a 3D inflow-outflow configuration
G. Nivarti and S. Cant
CP5 (4/6)
st
Turbulent diffusion flame modelling in large eddy
simulation (LES)
F. Shum-Kivan, B. Cuenot and E. Riber
CERFACS, France.
Diffusion flames appear in many practical systems and
are particularly present in spray combustion. In the
context of LES, the Thickened Flame approach initially
developed for premixed combustion is here adapted to
diffusion flames. A thickening factor based on the
scalar dissipation rate is introduced, and illustrated on
1D flame calculations, using either reduced or detailed
chemistry. To retrieve the correct flame wrinkling, an
efficiency function is derived from Direct Numerical
Simulation of a 3D reacting mixing layer. Finally, a
posteriori validation is presented with LES simulations
of the reacting mixing layer.
Turbulent flame speed is central to several theories of
turbulent flame propagation, but its experimentally
observed variation with turbulence intensity remains
unexplained. Until recently, DNS of turbulent reactive
flows has been restricted to moderate turbulence
intensities due to the prohibitive computational expense
involved at higher intensities. We have conducted a
parametric DNS study of premixed methane-air flames
interacting with intense turbulence by varying the
inflow turbulence intensity in a 3D inflow-outflow
configuration. The bending curve observed through our
simulations has been compared with recent
experimental results and the underlying mechanisms
have been investigated.
Numerical simulation of NOx formation
in syngas combustion
H. Watanabe1, T. Kawai2 and S. Ahn3
1
Kyushu University, Japan.
The University of Tokyo, Japan.
3
CRIEPI, Japan.
2
Characteristics of NOx formation in syngas combustion
under O2/CO2 combustion condition is numerically
investigated by means of homogeneous reactor model
of CHEMKIN, a direct numerical simulation (DNS)
with Arrhenius formulation (ARF) and DNS with the
flamelet/progress variable approach (FPV) in
comparison to air combustion condition. Results show
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 60 CP5: Turbulent combustion that the major pathways for NO formation drastically
change with O2/CO2 combustion condition in the zerodimensional computation. The characteristics shown in
the zero-dimensional computation is also confirmed in
ARF. It is also revealed that the general feature of
syngas combustion and the characteristics of NO
formation can be precisely captured by FPV.
CP5 (5/6)
Numerical and experimental analysis of laminar and
turbulent oxy-fuel jet flames using a direct
comparison of the Rayleigh signal
F. Hunger1, M. Zulkifli2, B. Williams2, F. Beyrau3 and
C. Hasse1
DNS and experiments of H2/He jets in a vitiated
turbulent crossflow
S. Lyra1, B. Wilde2, H. Kolla3, T. Lieuwen2
and J. Chen3
1
School of Mechanical Engineering, Georgia Institute of Technology,
USA.
3
2
Results are presented from a joint experimental and
numerical study of H2/He jet injected into a turbulent,
vitiated crossflow of lean methane combustion
products. High-speed stereoscopic PIV and OH PLIF
measurements are obtained alongside 3D DNS of inert
and reacting JICF with detailed H2/CO chemistry.
Under the investigated conditions a burner-attached
flame initiates uniformly around the nozzle. Significant
asymmetry is observed between the reaction zones
located on the windward and leeward sides, due to the
substantially different scalar dissipation rates. Vorticity
spectra extracted from the windward shear layer reveal
that the reacting jet is globally unstable.
1
2
3
Laminar and turbulent oxy-fuel jet flames are
investigated both experimentally and numerically with
emphasis on the direct comparison of the Rayleigh
signal. The Rayleigh signal was measured for both
flame conditions, especially correcting for background
light. Equivalently, the signal was processed
numerically based on the numerical species data and the
temperature. The laminar flame was used for validating
the procedure of processing the Rayleigh signal by
using the actual species and temperature data. In the
turbulent simulation, the Rayleigh signal was
incorporated in the flamelet/progress variable approach
in order to obtain the Favre-filtered Rayleigh signal
which is of non-linear nature.
Fuel effects on bluff-body stabilized turbulent
premixed flames
V. Katta1 and W. Roquemore2
1
LES flamelet-progress variable modeling of a
turbulent piloted dimethyl ether flame
S. Popp1, F. Hunger1, S. Hartl1, D. Messig1, B.
Coriton2, J. Frank2, F. Fuest3 and C. Hasse1
1
Chair of Numerical Thermo-Fluid Dynamics, ZIK Virtuhcon,
Technische Universität Bergakademie Freiberg, Germany.
2
3
Department of Mechanical and Aerospace Engineering, The Ohio
State University, USA.
Considering complex fuels, e.g. dimethyl-ether (DME),
is a current topic within the field of turbulent
combustion. Recent experimental investigations showed
significant differences in the flame structure when using
DME instead of methane. The scope of this work is the
analysis of the flame structure of a piloted DME-flame,
based on the Sydney/Sandia piloted methane flame
series, using a flamelet-progress variable approach
within an LES framework. Numerical results are
compared to a comprehensive set of experimental data,
including
velocity,
temperature
and
species
measurements. Furthermore, comparison of computed
and directly measured LIF and Rayleigh signals is
proposed.
Otto von Guericke Universität Magdeburg, Germany.
2
Innovative Scientific Solutions Inc, USA.
Air Force Research Laboratory, USA.
Previous experiments and simulations for a bluff-body
stabilized, turbulent lean premixed CH4/air flames
revealed that atom balances are not conserved across
the flame brush going from reactants to products. It was
found that the imbalance in C/H ratio results from
preferential diffusion. It is important to know whether
this imbalance is particular to methane fuel or also
occurs for aviation fuels such as JP8. In the present
paper, reacting flows for the bluff-body burner with
various fuel mixtures are simulated using a detailed
CFD code and investigated the fuel effects on C/Hatom-ratio distributions.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP5: Turbulent combustion Preferential diffusion effects in LES of mild
combustion with Flamelet Generated Manifolds
S. Abtahizadeh, R. Bastiaans, J. van Oijen
and P. de Goey
Eindhoven University of Technology, The Netherlands.
Preferential diffusion effects are investigated in flame
stabilization of turbulent lifted flames using LES with a
FGM-PDF model. The experimental test case is the
Delft JHC burner in which methane based fuel has been
enriched with various amounts of H2. A novel
numerical model is proposed based on the Flamelet
Generated Manifolds (FGM) to account for preferential
diffusion effects in autoignition. Afterwards, this model
is implemented in LES of the H2 enriched turbulent
lifted flames. Main features of these turbulent lifted
flames such as the formation of ignition kernels and
stabilization mechanisms are analysed and compared
with the measurements.
Resolved flame LES of the Cambridge stratified
burner using PFGM
F. Proch and A. Kempf
University of Duisburg-Essen, Germany.
Large eddy simulation results are presented for the
Cambridge stratified burner. The grid resolution is 100
µm, which is sufficient to resolve the progress variable
field for the applied premixed flamelet generated
manifolds approach without any kind of thickening,
filtering or tracking of the flame. To validate the
simulation, mean and rms radial profiles are compared
against the available measurement data. Subsequently,
an a-priori analysis of the progress variable- and
velocity fields is performed to extract the related subfilter contributions for different filter widths. In
addition, JPDFs of equivalence ratio and progress
variable from simulation and experiment are compared.
Large-eddy simulation/probability density function
modelling of Cambridge stratified flame
H. Turkeri and M. Muradoglu
Department of Mechanical Engineering, Koc University, Turkey.
61 time and space. For detailed chemistry representation of
the flame, an augmented reduced mechanism (ARM2)
for methane oxidation, which involves 19 species and
15 reactions (including NO chemistry) is incorporated
into LES/PDF calculations using ISAT algorithm. The
results are in good agreement with the experimental
data.
Challenging modeling strategies for LES of nonadiabatic turbulent stratified combustion
B. Fiorina1, R. Mercier1, G. Kuenne2, A. Ketelheun2, A.
Advic2, J. Janicka2, D. Geyer2, A. Dreizler2, E. Alenius3
C. Duwig3, P. Trisjono4, K. Kleinheinz4, H. Pitsch4,
S. Kang5, F. Proch6, F. Cavallo-Marincola6, A. Kempf6
1
TU Darmstadt, Germany.
3
Lund University, Sweden.
4
Sogang University Korea.
5
Lund University, Sweden.
6
Universität Duisburg-Essen, Germany.
2
This work provides a state-of-the-art picture of a
selection of computational approaches for LES of
stratified flame. Five simulations, which differ by
modeling approach, CFD code, combustion chemistry,
numerical techniques, computational meshes and user,
are presented. Each of these computational strategies is
designed to capture the filtered turbulent flame
propagation speed. In addition, as the models account
for non-adiabatic effects on the combustion chemistry,
quenching phenomena induced by heat losses are
captured. Encouraging similarities between the
computations and the experiments are observed. It
creates some confidence that these modeling
approaches are leading in the right direction.
CP5 (6/6)
Effects of preheat temperatures and turbulence
intensities on the disruption of the reaction zone in
high Karlovitz premixed flames
S. Lapointe and G. Blanquart
In this study, large-eddy simulation (LES)/probability
density function (PDF) method is applied to Cambridge
stratified flame in order to ascertain its ability to
calculate the details of the effects of the stratification. In
LES, large-scale motions are explicitly computed,
whereas the effects of subgrid scale (SGS) motions on
the large-scales are modelled. The interactions between
turbulence and chemistry are modelled by the PDF
method. LES/PDF equations are solved by
OpenFOAM/HPDF code which is second-order in both
Direct numerical simulations of premixed n-heptane/air
flames at Karlovitz numbers above 200 are performed
using
detailed
chemistry.
Different
unburnt
temperatures and turbulence intensities are used and
their effects on the flame structure are investigated. As
the unburnt gases are preheated, the viscosity ratio
across the flame is reduced and the effective Karlovitz
number at the reaction zone is increased. Both the
increase in the unburnt temperature and turbulence
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 62 CP5: Turbulent combustion intensity are found to lead to increased fluctuations in
the local fuel consumption rates. A new criterion for the
transition from the thin to broken reaction zones is
proposed.
LES/FDF of a lean premixed methane
counterflow flame
M. Rieth1, J. Chen2, F. Proch1, P. Lindstedt3
and A. Kempf1
1
Universität Duisburg-Essen, Germany.
3
2
Analysis of natural gas fired furnaces
with different oxygen enrichments
R. Prieler1, M. Demuth2 and C. Hochenauer1
1
2
Graz University of Technology, Austria.
Messer Austria GmbH, Austria.
A CFD modelling that integrates a steady flamelet
model with a detailed chemical mechanism is applied to
a natural gas fired lab-scale furnace under different
oxygen enrichments. Results are compared to measured
temperatures and heat fluxes inside the furnace. A
skeletal mechanism which considered 25 reversible
reactions and 17 species showed very good agreement
with the measurement for all oxygen concentrations in
the oxidizer with marginal differences in flame length
and maximum temperatures. These results are also
compared with those obtained by means of eddy
dissipation concept (EDC). Both approaches calculated
similar results for temperature and species
concentrations.
Lean premixed methane turbulent opposed jet flames in
fractal turbulence with different equivalence ratios,
experimentally investigated at Imperial College
London, have been simulated with a large eddy
simulation and transported filtered density function
(LES/FDF) method. The LES/FDF are performed
massively parallel with around 10 million particles on a
BlueGene machine to study lean premixed combustion
approaching extinction. The (conditional) statistics of
velocity and progress variable are compared to the
experimental data allowing for the assessment of
turbulence-chemistry interaction as well as the overall
performance of the LES/FDF predicting a turbulent
premixed flame.
Sensitivity of internal flow dynamics and boundary
conditions on a turbulent opposed jet flame
configuration
A. Ruiz, G. Lacaze, B. Coriton, J. Frank and J. Oefelein
Implicit large-eddy simulation of a Bunsen-like
burner with multi-scale turbulent forcing
S. Zhao1, N. Lardjane2 and I. Fedioun1
1
2
ICARE-CNRS, France.
CEA-DAM-DIF, France.
A methane-air Bunsen-like burner with multi-scale
turbulent forcing is simulated with a 5th order WENO
scheme at high resolution. A similar experiment is
conducted at ICARE, in which the forcing is achieved
using a system of three differently perforated grids. In
the simulation, the experimental 1D spectrum is taken
as an input for the generation of the turbulent flow field
to be injected at the inlet. An original characteristic
boundary condition has been derived to apply this
prescribed turbulent inlet. The non reacting simulation
matches quite well the experimental data. Reacting
cases are in progress.
Sandia National Labs, USA.
Effects of internal flow dynamics and boundary
conditions on a turbulent opposed jet flame
configuration are analyzed using the Large Eddy
Simulation technique. The geometry corresponds to that
used in experiments by Coriton and Frank for studies of
turbulence-chemistry interactions in canonically
generated flames. Specifying accurate boundary
conditions for simulations is challenging without
resolving the internal flow in the nozzles. Results
presented will provide a systematic characterization of
internal nozzle flow interactions with emphasis on
providing optimal flow conditions, detailed turbulence
characteristics at respective nozzle exits, and an
improved understanding of the effects these phenomena
have on various flame structures.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP6: Coal combustion 63 CP6: Coal combustion
Adaptive kinetic model for coal devolatilization in
oxy-coal combustion conditions
S. Iavarone1, C. Galletti2, F. Contino3, L. Tognotti2,
A. Parente1 and P. Smith4
1
Aero-Thermo-Mechanical Department, Université Libre de
Bruxelles, Belgium.
2
Department of Civil and Industrial Engineering, University of Pisa,
Italy.
3
Department of Mechanical Engineering, Vrije Universiteit Brussel,
Belgium.
4
Institute for Clean and Secure Energy, University of Utah, USA.
The oxy-combustion is emerging as the most likely
low-cost “clean coal” technology for both NOx and
SOx emissions reduction and carbon capture. The use of
CFD tools is crucial for cost-effective oxy-fuel
technologies development and environmental concerns
minimization. The coupling of detailed chemistry and
CFD simulations is still prohibitive and the
improvement of simple but reliable kinetic mechanisms
is therefore necessary. This work presents a CFD study
on coal pyrolysis, regarding implementation, validation
and uncertainty quantification of a reduced adaptive
kinetic model, able to predict the total volatile and tar
yields, depending on heating rate, temperature,
pressure, and coal type.
A modified two-step model for devolatilization
A. Richards and T. Fletcher
Brigham Young University, USA.
Although complex models of coal pyrolysis have been
developed based on chemical structure, simple but
accurate models are currently needed for incorporation
into large boiler simulation models. Many investigators
fit coefficients for a simple model to match predictions
of the complex model over a narrow range of heating
rate or temperature. In this paper, a modified two-step
model for devolatilization is presented. It is used by
combining the original two-step model with a corrective
function developed as part of the Yamamoto one-step
model. The original two-step model works well for
predicting yield values of total volatiles and tar for one
heating rate, but is not as accurate if used over a wider
range of heating rates, meaning a new set of parameters
must be generated for each new heating rate.
Combining the form of the original two-step model with
the corrective function from the Yamamoto model gives
the modified two-step model the predictive capabilities
of the original two-step model, but also the accuracies
inherent in the Yamamoto model compared to the CPD
model. The results for different types of coal are
presented here. The modified two-step model is shown
to be a very accurate model for calculating yields in the
devolatilization process over a wide range of heating
rates (5000 K/s to 1 million K/s). This gives the model
flexibility to model yields at any heating rate inside that
range.
A consistent approach for coupling the
devolatilization of coal particles
with tabulated chemistry
R. Knappstein1, A. Ketelheun1, G. Künne1, J. Köser2,
A. Dreizler2, A. Sadiki1 and J. Janicka1
1
Institute of Energy and Power Plant Technology, TU Darmstadt,
Germany.
2
Institute of Reactive Flows and Diagnostics, TU Darmstadt,
Germany.
Within this work the predictive capability of a FGM
combustion modelling strategy coupled with coal
devolatilization models is investigated. First, the
coupling of the devolatilizing coal particle and the finite
volume scheme is addressed. The verification assessing
the consistency regarding mass, species and enthalpy
conservation combined with the thermo-chemical states
extracted from the three-dimensional chemistry table is
outlined. Second, measurements will be used for
validation of this approach in a quasi-one-dimensional
configuration. At this, coal particles cross a laminar flat
flame whose high temperature causes the volatile gases
to leave the particle and react within their flammability
limits.
Macropore growth in char particles under different
gasification conditions
K. Wittig1, A. Richter1, M. Kestel1, P. Nikrityuk2 and
B. Meyer1
1
2
University of Alberta, Canada.
Macropore growth within a single char particle under
different gasification conditions is studied numerically.
Therefore, a numerical reconstruction method for a
porous particle surface using an adaptive octree-based
subdivision is applied. CFD calculations of single
reacting particles were carried out in order to provide
the temperature and species profiles across the particle.
This approach allows for the pore growth study in
several regimes. Developments of porosity and specific
surface area over carbon consumption are compared for
different points in an entrained-flow reactor.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 64 CP6: Coal combustion 1
2
How does turbulent fluid motion influence
heterogeneous combustion?
Application of a skeletal kinetic mechanism on LES
of a pulverized coal jet flame
J. Krüger1, N. Haugen2 and T. Løvås1
S. Ahn1, H. Watanabe2, K. Tanno1 and N. Hashimoto1
1
EPT, NTNU, Norway.
Sintef Energy AS, Norway.
2
A reactive-particle conversion model, taking into
account internal gradients of concentration, is integrated
into the open-source DNS code called "The Pencil
code". Char particle conversion at constant pressure in
isotropic turbulence with zero mean flow is studied,
using GRI 3.0 and a detailed 26-step mechanism to
model the homogeneous and heterogeneous reactions,
respectively. Mass, species and energy interaction
between the solid and the fluid phases are accounted
for. The focus of the study is on the effect of turbulent
scale and intensity on the reaction rate of the char. This
will be used to develop a turbulent combustion/
gasification model for heterogeneous reactions.
CRIEPI, Japan.
Kyushu university, Japan.
A numerical calculation of a pulverized coal jet flame
has been performed using large eddy simulation (LES)
technique to analyze the reaction field in detail. A
reduced skeletal mechanism generated from a detailed
kinetic mechanism through a reasonable reduction
process is applied in this calculation for more detailed
analysis. The result is verified through a comparison
with experimental results conducted in CRIEPI.
Important characteristics in coal combustion such as
distribution of temperature and gases, particle size and
behavior, flow stream are analyzed and discussed in this
work.
CP7: Rocket engines, ramjets, scramjets
Three-dimensional structure of hypergolic ignition
process for hydrazine/nitrogen dioxide un-like
doublet impinging gas jets
Y. Daimon1, H. Tani1, H. Terashima2 and M. Koshi3
1
University of Tokyo, Japan.
3
2
The understanding of hypergolic fuel ignition process is
very important to develop the bipropellant liquid rocket
engine. In this work, hydrazine (N2H4)/nitrogen
dioxide (NO2) un-like doublet impinging gas jets is
simulated to explore the hypergolic ignition processes
in N2H4/N2O4 bipropellant liquid rocket engines. The
Navier-Stokes equations with a detailed chemical
kinetics mechanism are solved to reveal the influence of
the chemical reaction, i.e. hydrogen abstraction by
NO2. We discuss the differences of three-dimensional
structure of hypergolic ignition process between 400
and 600 K of gas temperature.
Computational modeling of boron particle fueled
ducted rocket combustion chambers
B. Kalpakli and E. Acar
ROKETSAN Missile Ind., Turkey.
A detailed computational model for boron particle
combustion in a reactive and variable composition
atmosphere is developed. The main application area of
the model is Computational Fluid Dynamics (CFD)
based simulations of solid propellant ramjet combustion
chambers and it is aimed to construct a combustion
model for boron containing solid propellants. This
model includes most of the physical processes required
to define a high fidelity particle combustion simulation.
Combustion model consists of surface and gas phase
reactions along with phase change processes including
evaporation and boiling. The reaction rate modeling of
some similar studies are also improved for ramjet
combustion chambers.
Numerical simulation of turbulent combustion
between a hydrogen jet and a supersonic vitiated air
crossflow
A. Techer, G. Lehnasch and A. Mura
Institut Pprime, UPR 3346 CNRS, ISAE-ENSMA, Poitiers, France.
The future of high-speed transportation systems
depends on the development of hypersonic air-breathing
engines. In such conditions, the flow entering the
combustor is maintained supersonic to reduce the
excessive heating and dissociation of air. The
combustor operation therefore concentrates important
difficulties, which dictate the propulsive system
development. We report LES of an under-expanded
hydrogen jet released into a turbulent cross-flow of
vitiated air. This configuration is representative of
practical conditions, encountered for instance in the
dual mode ramjet combustor of the ONERA-LAERTE
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP7: Rocket engines, ramjets, scramjets facility. We investigate the turbulent mixing and
combustion processes downstream of the underexpanded jet for various operating conditions.
Numerical investigation of transverse hydrogen jet
into supersonic crossflow using
detached-eddy simulation
L. Zhaoyang, W. Zenguo, S. Mingbo and W. Hongbo
National University of Defense Technology, China.
Three-dimensional unsteady reacting flowfield that is
generated by transverse hydrogen injection into a
supersonic mainstream is numerically investigated
using detached-eddy simulation and a assumed sub-grid
PDF model. The inviscid flux of Naver-Stokes is
discretized by ninth-order WENO scheme and the
viscous flux is discretized by sixth-order center
difference scheme. The temporal discretization is done
by means of implicit LU-SGS method. Validation is
performed for the jet penetration height, and the
predicted result is in good agreement with experimental
trends. The results indicate that jet vortical structures
are generated as the interacting counter-rotating vortices
become alternately detached in the upstream
recirculation region. Although the numerical OH
distribution reproduces the experimental OH planarlaser-induced fluorescence well, there are some
disparities in the ignition delay times due to the
restricted availability of experimental and numerical
data.
Numerical study of flame dynamic characteristics in
a supersonic combustor with dual cavity
Y. Yixin, W. Hoogbo, W. Zhenguo and S. Mingbo
65 process of flame stabilization in a supersonic combustor
with tandem and parallel dual-cavity. The clipped
Gaussian PDF of temperature and multivariate β-PDF
of composition were implemented to calculate the subgrid chemical sources in the conservation equations.
The sub-grid variances of temperature and composition
were constructed based on the scale similarity approach.
Simulation reproduced the significant movement and
transformation of the flame structure during the
stabilization
process,
which
were
observed
experimentally.
Numerical simulation on detonation initiation and
propagation in supersonic combustible mixtures
with nonuniform velocities and species
X. Cai1, J. Liang1, Z. Lin1, R. Deiterding2 and Y. Che1
1
2
DLR, Germany.
Detonation initiation and propagation using a hot jet in
supersonic combustible mixtures with nonuniform
velocities and species is investigated through highresolution simulations. For nonuniform velocities, when
the velocity in the upper half channel V2=0.5Vcj, the
Mach reflection on the upper wall results in the
formation of a new Mach reflection near the interface,
which is a locally normal detonation wave. The
continuous collisions between the lower wall and the
upper triple point play an important role in the eventual
formation of a dynamic stable structures. When V2 is
increased to 0.6Vcj, 0.7Vcj, 0.8Vcj and 0.9Vcj, the
initiation process becomes more and more similar with
that in uniform supersonic combustible mixtures. For
nonuniform species, it makes a big difference when
exchanging the locations of the species in the upper half
channel and the lower half channel.
A hybrid LES/assumed sub-grid PDF closure model
was carried out to investigate the spatio-temporal
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 66 CP8: Ignition / quenching CP8: Ignition / quenching
CP8 (1/2)
The flame consumption speed – comparison of
theory and numerical simulations
Direct numerical simulations of kernel growth of
turbulent premixed syngas/air flames
1
2
3
G. Giannakopoulos , C. Frouzakis , M. Matalon and
A. Tomboulides1
1
2
3
Swiss Federal Institute of Technology, Switzerland.
University of Illinois Urbana-Champaign, USA.
The early kernel development of spherical expanding
syngas/air flames is studied using parametric direct
numerical simulations in homogeneous isotropic
turbulent flow fields with detailed chemistry and
transport. The effects of mixture composition
(equivalence ratio and CO/H2 ratio) and turbulence
parameters on the flame dynamics are investigated in
circular (2D) and spherical (3D) domains. Emphasis is
given on the local flame structure, the propagation
characteristics and on the proper definition of flame
speed that describes the growth rate of spherical
turbulent flames.
G. Giannakopoulos1, C. Frouzakis2, M. Matalon3 and
A. Tomboulides1
1
Department of Mechanical Engineering, University of Western
Macedonia, Greece.
2
Aerothermochemistry and Combustion Systems Laboratory, ETH
Zurich, Switzerland.
3
Department of Mechanical Science and Engineering, University of
Illinois, USA.
The notion of “flame consumption speed", conveniently
defined as the rate of fuel consumption in a premixed
flame, is discussed and results from the asymptotic
theory are compared to direct numerical simulations for
planar and spherically expanding flames. Differences
between "flame displacement speed" and "flame
consumption speed" are identified and quantified, both
theoretically and numerically. The discussion also
includes the possible definition of a Markstein length
based on the dependence of flame consumption speed
on flame stretch rate, and its relation to the more
common definition of Markstein length.
A statistical model to predict ignition probability
LES analysis of the influence of the turbulence
intensity on the critical ignition energy of a lean
methane/air flame
S. Mouriaux1, O. Colin1, B. Renou2 and D. Veynante3
1
IFP Energies Nouvelles, France.
3
EM2C, CNRS and Ecole Centrale Paris, France.
2
A key parameter to control the success of ignition in
Spark Ignition (SI) engines is the Minimum Ignition
Energy (MIE), minimum energy required to ensure the
growth and the propagation of the flame kernel.
Experimental studies by Cardin et al. highlighted two
regimes for the MIE depending on the Karlovitz
number. This work proposes quasi-DNS simulations of
ignition in a Turbulent Homogeneous Isotropic (THI)
velocity field with the same properties as in the
experiment, showing the ability of the TF-LES model to
reproduce the experimental results and explaining the
dependency of the MIE to the turbulent intensity.
L. Esclapez, E. Riber and B. Cuenot
CERFACS, France.
Based on a series of non-reacting LES solutions, a
model is proposed to predict ignition probability taking
into account the flame kernel motion. The probability of
presence of flame elements at each location is evaluated
and statistics of mixture and turbulence are used to
evaluate the probability of ignition success. This
reduced model then allows the use of Uncertainty
Quantification (UQ), to evaluate the sensitivity of
ignition probability to unknown parameters related to a
spark discharge.
A method for predicting sensitive rate coefficients
with high accuracy tested for the H2/CO/O2-system
T. Methling, M. Braun-Unkhoff and U. Riedel
German Aerospace Center (DLR), Institute of Combustion
Technology, Germany.
An evolutionary strategy and a gradient based solver are
presented, for the sophisticated optimisation of
chemical kinetic reaction models. The novel approach is
based on new variation methods of rate coefficients and
new evaluation methods of the distance between target
values (experimental) and simulation values. Both
solvers are tested on OH*-chemiluminescence data of
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP8: Ignition / quenching 120 shock tube experiments. For validation, the target
data is simulated and random errors are added. Both
solvers fit the simulation and experimental data with
high precision. Furthermore, the gradient based solver is
capable of predicting sensitive rate coefficients with
outstanding accuracy compared to present confidence
intervals.
CP8 (2/2)
Direct numerical simulation of an igniting, turbulent
jet with global n-heptane chemistry at enginerelevant conditions
A. Krisman and E. Hawkes
A direct numerical study of a three-dimensional,
turbulent, temporally evolving slot-jet ignition was
conducted. The fuel was n-heptane, represented by a
four-step global scheme which was selected to
reproduce the two-stages of autoignition of n-heptane
while permitting a feasible computational cost. The
results indicate a complex ignition process wherein
distinct low and high temperature auto-ignition events
lead to the formation of edge-flames. A combination of
propagating edge-flames and auto-ignition produce a
fully-burning nonpremixed flame. The edge-flames
observed are of a hybrid premixed/autoignition
structure previously observed in laminar flame studies
at similar thermochemical conditions.
Direct numerical simulation of investigation of
autoignition with split fuel injection
D. Shin and E. Richardson
University of Southampton, UK.
Direct Numerical Simulation is used to investigate the
effects of split fuel injection on autoignition. Two
pulses of gaseous n-heptane are sequentially injected.
The fuel issues into hot quiescent air with a jet
Reynolds number of 7200. The combustion is modelled
with a global four-step scheme, and additional passive
scalars are transported in order to characterise mixing
between fuel injected at different times. By varying the
pulse duration and pulse separation times, the
entrainment of air; the mixing between the two pulses;
and the effect on the ignition process are investigated.
67 Effects of hydrogen added on the ignition of isooctane in a diffusion layer
Z. Li and Z. Chen
SKLTCS, Department of Mechanics and Engineering Science,
College of Engineering, Peking University, China.
Effects of hydrogen addition on the ignition in a
diffusion layer between cold iso-octane and hot air is
examined using numerical simulation. Detailed
chemistry and transport are considered. The focus is
mainly on the influence of preferential mass diffusion
of hydrogen over iso-octane. The ignition delay time is
found to first decrease and then increase slightly as the
hydrogen blending ratio increases. The ignition
enhancement caused by hydrogen addition is shown to
strongly depend on the mass diffusivity of each fuel
component. Moreover, the movement of the ignition
front is investigated.
Predicting extinction in condensed phase combustion
in a counterflow geometry
S. Koundinyan, D. Stewart, M. Matalon and J. Bdzil
University of Illinois - Urbana Champaign, USA.
We present a two-dimensional combustion model of the
Titanium-Boron (Ti-B) system, which is thermodynamically consistent. For diffusion, we have
combined the traditional Fick’s law with MaxwellStefan diffusion coefficients for a three species model.
We have analyzed the model in counter-flow diffusion
geometry and predict the required diffusion coefficients
that correspond to experimentally observed combustion
temperatures. The numerical code is validated using
asymptotic analysis in the limit of complete
combustion. We predict the extinction strain rate for the
Ti-B system and compare the results between constant
and non-constant density approximations. The
presented analysis can be applied to other condensed
phase combustion systems.
Large eddy simulation of extinction limits in twodimensional plane buoyant turbulent
diffusion flames
S. Vilfayeau, J. White and A. Trouvé
Department of Fire Protection Engineering, University of Maryland,
USA.
The general objective of this project is to support the
development and validation of large eddy simulation
(LES) models used to simulate the response of fires to
the activation of a suppression system (using gaseous
agents or water sprays). The configuration in this joint
experimental/computational study corresponds to a
methane-fueled, two-dimensional, plane, buoyancy-
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 68 CP8: Ignition / quenching driven, turbulent diffusion flame driven to extinction
when exposed to increasing levels of nitrogen dilution
or water mist. The study is aimed at evaluating flame
extinction/re-ignition models using FDS and
FireFOAM, two advanced LES-based solvers
developed by the National Institute of Standards and
Technology and FM Global, respectively.
CP9: Two-phase flows
CP9 (1/2)
Counter-flow spray pulsated flames: from
experimental measurements to numerical simulation
Numerical study of alkane-air spray combustion
J. Brändle de Motta1, M. Boileau1, L. Zimmer1,
B. Robbes1, F. Laurent1 and M. Massot2
C. Nicoli1, P. Haldenwang1 and B. Denet2
1
2
Laboratoire M2P2, CNRS and Aix-Marseille Université, France.
IRPHE, CNRS and Aix-Marseille Université, France.
1
2
This numerical work concerns spray-flame propagation.
Spray is schematizes by alkane droplets located at the
nodes of a face-centered 2D-lattice, surrounded by
gaseous alkane-air mixture. The study focuses on sprayflame speed in rich spray: a simple reduced kinetics
derived for high alkane air mixtures is used. The main
parameters of the study are the lattice path, the liquid
loading, and the surrounding gaseous equivalence ratio.
Our results agree qualitatively with the experimental
observations: spray flame can propagate faster than pure
premixed flames with the same overall equivalence
ratio, as soon as droplet radius is large enough.
The scope of the present contribution is to set up and
simulate a configuration of stationary and pulsated
counterflow sprays flames, where the polydisperse
injected sprays are described through both Lagrangian
and Eulerian multi-fluid approach coupled to a gaseous
flow field in the low Mach number limit. We present
detailed comparisons with experimental measurements
designed for this purpose and using dedicated
diagnostics for quantitive comparisons. Such
configurations are intended to become reference
solutions in order to validate industrial code, as well as
their models and numerical methods for spray and gas
resolution
Spray modeling using a method of moment
approach with droplet size distribution
reconstruction
M. Pollack, S. Salenbauch and C. Hasse
Large eddy simulations of polydisperse turbulent nheptane spray flames with a dynamic ATF
procedure coupled with the FGM chemistry
reduction method
F. Sacomano Filho1, M. Chrigui2, A. Sadiki1 and
J. Janicka1
In order to model sprays in an Eulerian framework, the
Population Balance Equation (PBE) needs to be solved.
An efficient approach is based on the Quadrature Based
Methods of Moments (QMOM). However, evaporation
and dissapearance of the smallest droplets cannot be
accounted for accurately in QMOM. To overcome this
drawback, the droplet distribution is reconstructed
applying the recently developed 'Extended QMOM‘ [1]
for sprays. This allows a very accurate closure of these
fluxes. Finally, this approach is extended to a bivariate
formulation in order to include the temperature as
second internal coordinate.
[1] C. Yuan, F. Laurent, and R. Fox: Journal of Aerosol Science 51,
2012, 1-23.
1
Institute of Energy and Power Plant Technology, Technische
Universität Darmstadt, Germany.
2
Unité de Recherche Matériaux, Energie et Energies Renouvelables,
Université de Gafsa, Tunisia.
Investigations of the capability of a dynamic Artificially
Thickened Flame (ATF) procedure to describe the
behavior of turbulent partially prevaporized spray
flames in the Euler-Lagrange context are performed.
Focus is given on the interactions characteristics
between both phases and on the effects of the flame
front propagation within the multiphase flow. The
chemistry is described by the Flamelet Generated
Manifold (FGM) method using a detailed reaction
mechanism for n-heptane including 88 species and 387
elementary reactions. The configuration analyzed
consists of a spray jet flame stabilized by a pilot flame.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP9: Two-‐phase flows 69 Good agreement with experimental data validates the
proposed approach.
Toward the fully realizable large eddy simulation of
disperse phase flows: Eulerian kinetic modelling
and associated numerical methods
M. Sabat1, A. Vié1, A. Larat1 and M. Massot2
1
2
The Large Eddy Simulation of disperse phase flows,
like droplets in aeronautical combustors, still requires
further research and developments to improve
predictivity as well as efficiency. Eulerian moment
methods are preferred because of their intrinsic HPC
ability. Here we present and validate a complete LES
strategy based on the use of an anisotropic Gaussian
closure for the droplet velocity distribution, a filtering at
the kinetic level, and high order realizable numerical
strategies to preserve the mathematical properties of the
resulting modelling approach with a sufficient
precision. The model is evaluated on configurations of
increasing complexity that exhibit its main features.
Analysis of multi-phase material model for
Al/AlOx droplet
K. Lee and D. Stewart
We present a multi-phase model of a spherical
Aluminum (Al) droplet coated with Aluminum
Oxide(AlOx). The effect of temperature variations on
the droplet is analyzed up to 2300K. Solid species are
considered as an elastic isotropic solid and liquid
species are given by modified form of Birch/Murnaghan
and Fried-Howard free energy EOS. We analyze the
influence of phase change in Al on AlOx at the
interface and compute localized radial and tangential
stress variations. A constitutive mixture relation of solid
Al and liquid AlOx is considered and compared with
the dual-layered spherical model.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 70 CP9: Two-‐phase flows CP9 (2/2)
st
Development of a turbulent liquid flux model for
Eulerian-Eulerian multiphase flow simulations
S. Puggelli1, A. Andreini1, C. Bianchini1, B. Facchini1
and F. Demoulin2
1
Department of Industrial Engineering (DIEF), University of
Florence, Italy.
2
CORIA (COmplexe de Recherche Interprofessionnel en
Aérothermochimie), Rouen, France.
Present work introduces an Eulerian-Eulerian solver for
multiphase flows proposed to include slip velocity
effects in the framework of quasi multiphase approach.
Particular attention is hence devoted to the turbulent
liquid flux modelling: an innovative second order
closure is derived and implemented in the Eulerian
solver derived from the Eulerian Lagrangian Spray
Atomization (ELSA) model. A detailed analysis of the
resulting solver capabilities is performed exploiting a jet
in crossflow test case at two different density ratios.
The comparison with the experimental results shows
that the solver leads to physically consistent
improvements in the description of liquid injection
development.
A monotonic mixing-describing composition-space
variable for the flamelet formulation of spray flames
B. Franzelli1, A. Vié2 and M. Ihme1
1
2
CTR - Stanford University, USA.
The classical mixture-fraction formulation, commonly
employed as describing variable for gaseous diffusion
flames, cannot be used for spray flames due to its nonmonotonicity caused by the evaporation source term in
the corresponding conservation equation. By addressing
this issue, a new mixing-describing variable, called
effective composition, is defined to enable the analysis
of spray-flame structures in composition space. This
effective composition variable is employed for the
derivation of a spray-flamelet formulation. The
structure of laminar one-dimensional counterflow spray
flames is numerically solved in the new phase space and
a comparison with the physical solution is performed to
demonstrate model consistency.
Numerical investigation of shear-driven primary
breakup of liquid fuel flows
developed and applied to primary breakup of liquid fuel
flows. The Robust Conservative Level Set (RCLS)
method uses high-order WENO schemes on mixedelement unstructured meshes to solve the transport
equation for the level-set variable. The method is
implemented within the framework of OpenFOAM, and
is fully parallelised. The present study uses the new
capability to understand the phenomenology observed
during prefilming airblast atomisation of a planar liquid
sheet, for commercial aircraft application, which is
essential for effective control of fuel atomisation and
cleaner, more efficient combustion processes.
Numerical simulations of kerosene spray
atomization with various hybrid breakup models
T. Liu1, L. Hu2, Y. Wu3, D. Zhao3 and G. Wang4
1
School of Engineering Science, University of Science and
Technology of China, China.
2
School of Mechanical Engineering, Shanghai Jiaotong University,
China.
3
Hypersonic Aircraft Research Center, China Aerodynamics
Research and Development Center, China.
4
School of Aeronautics and Astronautic, Zhejiang University, China.
Numerical simulations of kerosene spray are performed
to evaluate the droplet size and distribution during the
spray process of a nozzle using OpenFoam. Six hybrid
breakup models, i.e. the combinations of two primary
breakup models (the hollow-cone injector model and
the Blob Sheet Atomization model) and three secondary
breakup models (the KHRT, TAB and ETAB models),
and LISA model are utilized to describe the whole spray
process and the accuracies of their predictions are
evaluated by comparing with the experimental data. The
collision and coalescence of droplets are considered
using the trajectory model and the wall refection model.
The Sauter mean diameter (SMD) of the droplets and its
distributions are adopted to evaluate those models’
capabilities to predict the spray process of the nozzle.
After comparing between experimental data and
predicted results and analyzing the differences of
predicted results from different breakup models, we can
draw a conclusion that predicted results obtained using
hollow-cone injector model and KHRT model are better
than those obtained using other models for this nozzle.
For the primary breakup models, the Blob Sheet
Atomization model underestimated the breakup rate
around the nozzle’s orifice. The predictions of KHRT
model are the best among three secondary breakup
models. In general, the predicted results show that the
secondary breakup model plays a major role on the
spatial distribution of droplet diameter.
C. Bilger, T. Pringuey and R. Cant
A novel state-of-the-art numerical capability for
efficient modelling of multiphase flows has been
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP9: Two-‐phase flows 1
2
71 Compressibility effects in the initial transient of
high-pressure Diesel injection
Modeling and simulation of a dense
evaporating spray
M. Arienti1 and M. Sussman2
F. Doisneau, M. Arienti and J. Oefelein
Sandia National Labs, USA.
Florida State University, USA.
We discuss the turbulent dispersion of atomized spray
in response to the timed opening of a high-pressure,
sub-critical, non-cavitating Diesel injector. Of interest
in this study is the capability of modeling compressible
flow in both gas and liquid phases while maintaining a
sharp interface between the two. The internal and
external flows are seamlessly calculated across the
injection orifice using the Moment of Fluid method,
with an embedded boundary technique to represent the
injector’s walls. A realistic equation of state,
experimentally calibrated at high pressure for liquid ndodecane, is implemented to relate the transient spray
characteristics to the orifice opening.
We compute a dense spray as it is transported by and
evaporates in a turbulent reacting flow. The
configuration is representative of a sub-critical highpressure reacting Diesel jet. State-of-the-art models and
methods for both gas and liquid phases are coupled in a
way that optimizes the load balance and the accurate
resolution of the couplings, leading to a novel
architecture for spray combustion parallel codes. This
work aims at assessing the capabilities of a massively
parallel LES solver in performing industrial simulations
of sub-critical injection and combustion, which is an
important tool for the design of advanced engines.
CP10: New technologies
CP10 (1/2)
much more regular. Our model describes the flame
anchoring phenomena when the combustion wave is
stabilized inside of the porous media for a range of
inlet velocities.
A discrete model of gas combustion in porous media
F. Sirotkin1, R. Fursenko2 and S. Minaev1
1
Far Eastern Federal University, Russia.
Khristianovich Institute of Theoretical and Applied Mechanics,
Russia.
2
A discrete quasi three-dimensional model of gas
combustion in porous media is proposed. The porous
media is represented as the set of randomly placed solid
grains which are connected trough the artificial solid
plate to mimic thermal conductivity between grains.
The propagation of the combustion wave is simulated in
the frame of thermal-diffusion model with the
prescribed flow field computed preliminary using
Lagrangian particles method. Dependencies of
combustion wave velocity on the inlet gas velocity for
different equivalence ratios and porosities are obtained
and compared with the continuous one-dimensional
thermal-diffusion model. Our results imply that the
flame propagation in the porous media can be
considered as a collective process, when the actual
combustion wave can be represented by a set of
individual flame fronts propagating in the mutually
connected micro-channels of the different diameter. The
discrete structure of the combustion wave is most
prominent when the inlet velocities are small and the
flame propagation is accomplished with pulsations of
flame front fragments. When the inlet velocities are
high enough, the propagation of the combustion wave is
The effect of the three-dimensionality of the flame
front inside a radial-flow porous burner – a detailed
DPLS numerical study
I. Dinkov, P. Habisreuther and H. Bockhorn
Karlsruhe Institute of Technology, Engler-Bunte-Institute, Division
for Combustion Technology, Germany.
In the present study combustion process inside a porous
inert media (PIM) has been numerically investigated
using a real porous inert structure obtained from
computer tomography. The results showed that the
flame structure is substantially affected by the topology
of the PIM at the pore level. Therefore, significant
spatial fluctuations of local properties such as
temperature and velocity are presented along the space
and made obvious the three-dimensionality of the flame
front inside the PIM. A possible way to take these
spatial fluctuations into account with an assumption
analogous to the Boussinesq hypothesis is suggested.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 72 CP10: New technologies Lean hydrogen flames in a narrow adiabatic channel
C. Jiménez, D. Fernández-Galisteo and V. Kurdyumov
CIEMAT, Spain.
We present results of direct simulations of lean
hydrogen-air flames propagating in planar narrow
adiabatic channels, using detailed chemistry. Our
simulations show that, as already predicted by
numerical analysis within a thermo-diffusive
approximation and Arrhenius chemical kinetics, when
Le<1 double solutions, symmetric and non-symmetric,
can exist and coexist for the same set of parameters.
Moreover, the propagation velocities of the symmetric
and the non-symmetric flames are very different, and so
is the flashback critical condition. This can have
important safety implications in devices designed to
burn hydrogen in a lean laminar premixed way, as, for
example, in micro-combustion devices
A numerical investigation of
heterogeneous/homogeneous combustion of ndodecane over Pt for microcombustion
E. Tolmachoff, A. Booth, I. Lee, W. Allmon
and C. Waits
ARL, USA.
For the next generation of portable chemical-toelectrical power converters, high temperature operation
with liquid fuels will be critical for high efficiency and
energy density. This work investigates the combustion
of n-dodecane in a porous platinum-coated foam
reactor. A lumped parameter model describes mass
transport between the gas and the catalyst surface.
Homogeneous chemistry is described by a skeletal
mechanism for low and high temperature n-dodecane
combustion.
Surface
reactions
of
abundant
homogeneous species at the Pt surface are treated as
lumped and irreversible. The resulting combined
mechanism satisfactorily predicts CO2 yield from
experiments for moderate to high temperatures (> 650
C).
Direct numerical simulation of MILD combustion
U. Göktolga, J. van Oijen and P. de Goey
Eindhoven University of Technology, the Netherlands.
MILD combustion is a promising concept which
combines dilution and preheating, and decreases
harmful emissions like NOx. It has been applied to
industrial furnaces for years, but the physical
phenomena occurring are yet to be revealed. In this
study, 2D and 3D DNS calculations of MILD
combustion in the form of auto-igniting mixing layers
were performed. Effects of different parameters like
heat loss and preferential diffusion were investigated.
We found that the heat loss effects are crucial in
predicting ignition delay and flame structure.
Furthermore, we observed that the preferential diffusion
effects were present even in highly turbulent
environment.
Large-eddy simulation of a MILD combustion
burner using conditional source-term estimation
J. Labahn and C. Devaud
University of Waterloo, Canada.
Conditional Source-term Estimation (CSE) has been
successfully applied to different turbulent combustion
problems. In the current study, Large Eddy Simulations
(LES) of the Delft-Jet-in-Hot-Coflow burner, with a
two mixture fraction CSE formulation, are performed to
predict temperature and velocity profiles, and lift-off
heights for two different flames, DJHC-4100 and
DJHC-8100. The mean temperatures and velocities are
in good agreement with the experimental data, with a
slight overprediction of the centerline temperature. The
predicted lift-off height for the DHJC-4100 flame is
found to be lower than the experimental value,
suggesting that a third conditioning variable may be
needed for improved predictions.
CP10 (2/2)
Numerical aspects of the shockless explosion
combustion
P. Berndt1, R. Klein1 and C. Paschereit2
1
2
Freie Universität Berlin, Germany.
Technische Universität Berlin, Germany.
The shockless explosion combustion is a novel
approach to constant volume combustion in gas
turbines. In contrast to pulsed detonation, it aims to
avoid strong shock waves by utilizing homogeneous
auto ignition, similar to the HCCI process in internal
combustion engines. Recharging is handled analogous
to pulsejets through the pressure waves in the
combustion chamber. We introduce the process in detail
and familiarize the audience with the numerical
challenges associated with its simulation.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP10: New technologies 73 Steady laminar one-dimensional flame solvers for
modelling ions in flames
Simulation of turbulent premixed combustion with a
self-consistent plasma model for initiation
B. Lee, M. Cha, H. Im and S. Chung
H. Sitaraman and R. Grout
National Renewable Energy Laboratory, USA.
For predicting the amount of ions and their distribution
in flames with or without external electric fields,
Cantera-based open-source solvers for steady laminar
one-dimensional flames, PREMIX++ and OPPDIF++,
are introduced. To model the transport of charged
species in flames, existing C++ classes of Cantera for
one-dimensional reacting flows are modified to
incorporate drift flux terms and a Poisson's equation of
electric potential. With an extended reaction mechanism
for ion chemistry proposed to model both lean and rich
premixed methane flames, validation against Goodings'
experiments is presented. Prediction of current-voltage
characteristics for an opposed-flow diffusion flame is
demonstrated.
Turbulent combustion simulations are typically initiated
using a time-dependent heat source kernel (representing
an electric spark) in the computational domain to
activate chemical reactions. In reality, the spark not
only increases temperature of the background gas via
ohmic heating, but also creates reactive radical species
via electron impact. A detailed multi-species plasma
discharge model is coupled with turbulent combustion
equations to self consistently capture ignition. A
spectral deferred correction (SDC) based multi-rate
integrator will be used in the combustion solver. The
final work will compare the reaction pathways that
result in ignition to the active pathways under
conventional hot-spot ignition model.
Application of a two-fluid plasma model to the
simulation of premixed flames under electric fields
Computational modeling of plasma assisted
combustion in gas turbines for
electric power generation
T. Casey1, P. Arias2, J. Han2, M. Belhi2, F. Bisetti2,
H. Im2 and J. Chen2
A. Ehn1, J. Zhu1, P. Petersson1, Z. Li1, M. Alden1, C.
Fureby2, T. Hurtig2, N. Zettervall2, A. Larsson2 and
J. Larfeldt3
1
University of California, Berkeley, USA.
King Abdullah University of Science and Technology (KAUST),
Saudi Arabia.
2
1
2
In the numerical studies, interested in combustion
interaction with electric fields, the effects of nonthermal electrons are not considered. To account for
those effects, a two-fluid plasma model is developed.
The gas mixture and electron transport equations are
derived separately from Boltzmann’s kinetic theory.
Boundary conditions for the electric potential, charged
species concentrations and electron energy and velocity
are established. The model is implemented in a fully
compressible DNS reacting flow code to calculate the
distribution of charged species and electric field in a
1D-premixed flame. An analysis of the effect of electric
field on the flame properties is proposed.
3
LTH, Sweden.
FOI, Sweden.
Siemens, Sweden.
To reduce the risk of combustion instabilities, increase
fuel flexibility and combustion efficiency, electrical
energy can be deposited in the flame using e.g.
microwave radiation. This will create a non-thermal
plasma modifying the flame chemistry. Here, the
development and validation of a finite rate chemistry
Large Eddy Simulation (LES) model is described. The
model is based on a skeletal methane-air mechanism,
extended by O3-chemistry, singlet O2-chemistry,
chemoionization, electron excitation, electron impact
dissociation, ionization and attachment, and N2
reactions. The LES model is applied to a methane-air
low-swirl stabilized flame. An applied electrical field
increases the turbulent flame speed by 15%, making the
premixed bowl-shaped flame move closer to the burner
mouth. Good agreement between the experimental and
computational results is observed both with and without
microwave stimulation.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 74 CP11: Detonation CP11: Detonation
CP11 (1/3)
st
Flame acceleration in channels with cold walls
C. Dion1, B. Demirgok2, V. Akkerman2, D. Valiev3 and
V. Bychkov1
FORCE method. The study is performed with the
constant emission rate of igniter. The space-time
evolution of flow variables for three different cases of
propellant burning rate is examined.
Symmetric Baer and Nunziato model
1
Dept. Physics, Umea University, Sweden.
2
Dept. Mechanical and aerospace Engineering, West Virginia
University, USA.
3
Dept. Applied Physics, Umeå University, Sweden.
The present work considers the problem of premixed
flame front acceleration in micro-channels with smooth
cold non-slip walls in the context of the deflagration-todetonation transition; the flame accelerates from the
closed channel end to the open one. Recently, a number
of theoretical and computational papers have
demonstrated the possibility of powerful flame
acceleration for micro-channels with adiabatic walls. In
contrast to the previous studies, here we investigate the
case of flame propagation in channels with isothermal
cold walls. The problem is solved by using direct
numerical simulations of the complete set of the NavierStokes combustion equations. We obtain flame
extinction for narrow channels due to heat loss to the
walls. However, for sufficiently wide channels, flame
acceleration is found even for the conditions of cold
walls in spite of the heat loss. Specifically, the flame
accelerates in the linear regime in that case. While this
acceleration regime is quite different from the
exponential acceleration predicted theoretically and
obtained computationally for the adiabatic channels, it
is consistent with the previous experimental
observations, which inevitably involve thermal losses to
the walls. In this particular work, we focus on the effect
of the Reynolds number of the flow on the manner of
the flame acceleration.
R. Saurel
University Institute of France.
The Baer and Nunziato (1986) is nowadays widely used
in two-phase flow community and particularly in
granular media deflagration and detonation modelling.
However this model is not symmetric in the sense that a
carrier phase is considered with a dispersed granular
one. It implies that the interfacial pressure in the
equations is approximated to the gas one while the
interfacial velocity is assumed to be the solid one. In
many situations this is confusing as both phases may
have very high densities, such as detonation products
and reacting condensed material for example. This is
also limiting when deaingl with gas - granular materials
interfaces.
In a former contribution (Saurel et al., 2003) a
symmetric variant of the BN model was derived for
fluid mixtures; i.e. in the absence of intergranular
effects. The addition of granular effects (contact
pressure, intergranular stress) seemed impossible to
insert. Thanks to a deeper analysis granular effects are
inserted in a symmetric BN formulation, while
preserving both hyperbolicity and agreement with the
second law of thermodynamics. Computational results
demonstrate capabilities of the method.
3D simulation of discrete combustion waves in
mechanically activated powder mixtures
Numerical simulation of shock wave dynamics in
internal ballistics of gun
N. Chirame, D. Pradhan and S. Naik
Defence Institute of Advanced Technology, India.
In this work, we have simulated a 1D two phase flow
Baer-Nunziato model of internal ballistics to study the
shock wave motion inside the gun chamber. The model
consists of conservation equation of mass, momentum
and energy for gas and solid phase with conservation
equation for solid volume fraction. The constitutive
equations are co-volume equation of state and mass
transfer rate of solid propellant. First ORder CEntred
method with operator splitting technique has been
employed to solve the equations. The academic case is
simulated to study the shock capturing nature of
S. Rashkovskiy1 and A. Dolgoborodov2
1
Institute for Problems in Mechanics, Russian Academy of Sciences,
Russia.
2
N. Semenov Institute of Chemical Physics, Russian Academy of
Sciences, Russia.
A method of numerical simulation of propagation of a
chemical reaction in powder mixture is considered. The
method involves two steps: a simulation of powder
structure and simulation of propagation of reaction
wave in this structure. We discuss and estimate the
mechanisms of transferring of the thermal pulse
between the particles. The parametric calculations and
the animation of the results of calculations were made.
It is shown that combustion of powder mixture proceeds
non-uniformly in space and time. The results of
simulations are compared with experimental data.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP11: Detonation Simulations of compressible gas-dust flows
E. Oran and R. Houim
University of Maryland, USA
In dust flows of current interest, gas flow speeds can
range from highly subsonic to supersonic, the grain
packing can range from fully packed to completely
dispersed in the gas, and both the gas and the dust can
range from chemically inert to highly exothermic.
Examples include coal dust in mines, regolith on the
lunar surface, and desert or beach sand, corresponding
to flows generated by explosions, asteroid impact, and
soft aircraft landings. To cover the necessary parameter
range, we solve coupled sets of Navier-Stokes equations
describing the background gas and the dust. As an
example, an reactive-dust explosion in air, one that
results in a type of shock-flame complex, is described
and discussed.
Detonation shock propagation through
nitromethane embedded metal foam
B. Lieberthal and D. Stewart
Explosive devices manufactured from nitromethane and
metal foam have numerous practical military and
industrial applications because the individual
components are safe to transport and easy to assemble.
We run hydrodynamic simulations of a shock wave
propagating through metal foam using a reactive flow
model in the ALE3D software package. We explore in
depth the applied pressure and energy of the shock
wave and its effects on the fluid and inert material
interface. We sample foam models of varying pore size
composed of low and high impedance metals and test
their viability as a hybrid explosive material.
CP11 (2/3)
Three-dimensional simulations of shock-induced
combustion around a spherical projectile with
various diameters
Y. Sakuragi and A. Matsuo
Keio University, Japan.
We carried out three-dimensional simulations of ShockInduced Combustion around a spherical projectile
flying at 1931 m/s into H2-Air mixture, with two-step
reaction model. The unstable behavior in front of
projectile is revealed by a series of simulations with
various projectile diameters. The bigger diameter case
(24 mm) shows the fully three-dimensional unsteady
75 behavior, but the axisymmetric oscillations with
constant period are observed in the smaller case (15
mm). In the intermediates, the three-dimensional
instabilities gradually develop in the flow field with
projectile scale-up. Thus, the three-dimensional
simulations succeed in obtaining unstable behavior
observed in the previous experiments.
Weakly nonlinear detonations: theory and numerics
L. Faria1, A. Kasimo1 and R. Rosales2
1
2
MIT, USA.
Starting from the compressible reactive Navier-Stokes
equations, we derive an asymptotic theory of weakly
nonlinear detonations with diffusive effects retained.
Focusing on the inviscid limit, we show by linear
stability analysis and direct numerical simulations that
the asymptotic system captures several features of
detonations, such as (1) existence and instabilities of
ZND waves, (2) galloping and chaotic detonations in
one dimension, and (3) cellular structures in two
dimensions. Finally, we study the effect of dissipative
processes on the structure and stability of the traveling
waves, and compare the ideal predictions with their
dissipative counterpart.
A compressible LEM-LES strategy (CLEM-LES)
for modeling turbulent detonation propagation
B. Maxwell1, S. Falle2, G. Sharpe3 and M. Radulescu1
1
2
3
University of Ottawa, Canada.
Blue Dog Scientific Ltd., UK.
A turbulent combustion model based on the Linear
Eddy Model for Large Eddy Simulation (LEM-LES)
has been developed to study highly compressible and
reactive flows involving very rapid transients in
pressure and energy. In the current work, the model is
used to simulate 2D unsteady and turbulent detonation
propagation, in a narrow channel, which involves a
premixed methane-oxygen mixture at low pressures.
The results have shown that the simulated detonation
propagates at an average velocity that corresponds to
the theoretical Chapman-Jouguet (CJ) velocity.
Furthermore, the model captures well the twodimensional cellular structure that is observed in
corresponding shock tube experiments.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 76 CP11: Detonation Set-valued solutions for detonations with losses
1
1
1
R. Semenko , L. Faria , A. Kasimov and B. Ermolaev
1
2
2
N. N. Semenov Insitute of Chemical Physics, Russia.
We consider the 1D model of gaseous detonation in the
packed bed of inert solid particles. The model is given
by the reactive Euler equations with losses of heat and
momentum and the Arrhenius-type heat release. The
goal is to see if this simplified model can accurately
reproduce the well-known detonation velocity deficit
due to losses. We study the dependence between
detonation speed and the amount of losses for steadystate solutions. Particularly, it is shown that this
dependence allows for multiple or even set-valued
solutions. The latter means that there can be a
continuous set of solutions for a given fixed set of
problem parameters.
Two-phase simulations of TNT/Aluminium
afterburning during explosions
E. Fedina and C. Fureby
Swedish Defence Research Agency – FOI, Sweden.
Present study investigates the afterburning from
explosions of a TNT charge and a TNT charge
containing aluminium particles (TNT/Al) at two heights
above ground, to demonstrate that numerical
simulations can facilitate evaluation of the performance
of high-explosives. The simulations are conducted using
two-phase finite rate chemistry Large Eddy Simulation
model in Euler-Lagrange form, incorporating
interaction between phases by a two-way coupling. The
results indicate that pure TNT requires shock-mixing
layer interaction to sustain afterburning, while TNT/Al
generates mixing through particle-gas interactions;
hence the afterburning mainly depends on the oxygen
supply. The simulations results show good agreement
with the experimental data.
CP11 (3/3)
Is is possible to achieve DDT behind a continuously
growing Mach stem?
Y. Lv and M. Ihme
moving shock that is reflected at a wedge. This
configuration allows to isolate all physical mechanisms
that are of relevance in triggering detonation.
Parametric studies will be performed to analyze effects
of the wall and relevant gas properties. For the
numerical approach, a high-order discontinuous
Galerkin method is used, and its capability for
addressing such challenging multi-physics flow
problems will be demonstrated.
Numerical investigation on cellular H2-O2-Ar
detonation evolution in mixtures with different
hydrogen concentrations
Q. Xiao, W. Fan, H. Li, K. Wang and Q. He
School of Power and Energy, Northwestern Polytechnical University,
China.
Two-dimensional numerical simulations of cellular
detonation evolution in H2-O2-Ar mixtures at a low
pressure of 6.67 kPa have been performed in a 20 mm
by 200 mm tube with a detailed chemistry kinetic
mechanism. The initial overdriven detonation has been
directly onset by a circular pocket of high pressure and
temperature. The present study mainly focuses on the
whole process of how initial overdriven detonation
evolves to the final stable cellular detonation. Also, the
influence of varied spatial hydrogen and Ar
concentration on cellular detonation propagation is also
investigated.
On the influence of instabilities on the direct blast
initiation of two-dimensional detonations
H. Ng1, C. Kiyand12, G. Morgan2 and N. Nikiforakis2
1
Concordia University, Montreal, Canada.
Cavendish Laboratory, Department of Physics, University of
Cambridge, Cambridge, UK.
2
Two-dimensional,
high-resolution
numerical
simulations are carried out in this study to investigate
the influence of instabilities on the direct initiation of
weakly unstable detonations. The computations are
performed using Euler’s equations with a one-step
Arrhenius kinetic model by general-purpose computing
on graphics processing units (GPGPU). The
introduction of an initial sinusoidal perturbation on the
surface of the high energy source region with different
amplitudes and wavelengths to generate cellular
instabilities is assessed for either promotion of direct
detonation initiation or adverse effect.
Combustion behind a Mach stem is a fundamental
mechanism for front propagation of unstable detonation
waves. In this study, the reflection of a Mach-shock in a
premixed gas mixture will be considered to examine the
detonation mechanism. The Mach-stem is created by a
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP11: Detonation 77 Detonation in a radial supersonic outflow with
simplified and realistic chemistry
Numerical investigation on detonation initiation and
propagation in supersonic reactive flows
S. Korneev and A. Kasimov
J. Li, Q. Xiao and W. Fan
We study cylindrical detonation in a radial supersonic
expansion for various heat release models. At first, we
considered simple Arrhenius kinetics. Two types of
solutions were found which give different instability
pattern: square-wave cylindrical detonation and
cylindrical detonation with very thin induction zone.
The square-wave solution, as it was seen numerically,
tends to collapse to the source and the other type of
steady-state solution tends to expand. It was found, that
expanding solution can be stabilized by set of obstacles
which surrounds the detonation. We also find that
obstacles barrier placed into radial supersonic inert
expansion can initiate the cylindrical detonation. We
perform comprehensive parametric study of radius of
the steady state solution on incoming flow parameters.
Also we study cylindrical steady-sate solution for
Arrhenius kinetics with local density dependence and
realistic two stages kinetics for hydrogen-oxygen
mixture.
School of Power and Energy, Northwestern Polytechnical University,
China.
The initiation and propagation process of detonation
waves in a supersonic combustible flow was
numerically investigated. An auto-ignition detonation
phenomenon was initiated by a wedged channel. The
time-dependent two-dimensional Euler equation was
used to describe the chemically reacting flow with
detonation combustion. The influence of the incoming
Mach number and configuration of detonation chamber
on the detonation initiation and propagation process was
systematically investigated. The existing form of
detonation waves under different conditions, the
interaction between complex waves and the transition
condition between upstream propagating normal
detonation and standing oblique detonation wave were
also addressed.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 78 CP12: Industrial furnaces CP12: Industrial furnaces
Effect of particle shrinkage on the biomass pyrolysis
behavior in a high-temperature
entrained-flow reactor
X. Ku, T. Li and T. Løvås
University of Science and Technology (NTNU), Norway.
Effect of particle shrinkage on biomass pyrolysis
behavior in a laboratory-scale entrained-flow reactor is
numerically investigated by an Eulerian-Lagrangian
CFD model proposed in our earlier paper. The operating
temperature is high (1400 °C) and two shrinkage submodels are adopted. The two different sub-models
consist of (1) constant particle volume, and (2) constant
particle density. Simulation results are analyzed both
qualitatively and quantitatively in terms of particle
distribution, product gas composition, pyrolysis time
and particle residence time. Moreover, the calculated
results are compared with the experimental data
available in the literature.
Avoiding ring formation in cement kilns
D. Lahaye
TU Delft, The Netherlands.
Avoiding the formation of rings in rotary kilns is an
issue of primary concern to the cement production
industry. We developed a numerical combustion model
that revealed that in our case study rings are typically
formed in zones of maximal radiative heat transfer. This
local overheating causes an overproduction of the liquid
phase of the granular material, which tends to stick to
the oven's wall and to form rings. To counteract for this
phenomenon, we propose to increase the amount of
secondary air injected to reduce the peak temperature.
Experimental validation at the plant has confirmed that
our solution is indeed effective. For the first time in
years, the kiln has been operating without unscheduled
shut-downs, resulting in hugely important cost savings.
Large eddy simulation of coal and biomass co-firing
M. Rabacal1, M. Costa1 and A. Kempf2
1
2
Instituto Superior Tecnico, University of Lisbon, Portugal.
University of Duisburg-Essen, Germany.
A large eddy simulation of coal and biomass co-firing
in a large-scale laboratory furnace is presented. The inhouse CFD solver PsiPhi, optimized for massive
parallel execution, is used. Coal and biomass particles
are tracked individually using a Lagrangian approach.
The combustion steps of drying and devolatilization are
modeled using a thin film approach and a single first
order reaction model, respectively. Coal char
combustion is modeled using the Smith model, whereas
for biomass a diffusion-limited surface reaction rate
model is used. Major gas species distribution, particle
properties conditional to gaseous properties and particle
combustion history are discussed.
A laboratory-scale downsizing procedure for highly
resolved LES of large-scale combustion system
B. Farcy, D. Midou, L. Vervisch and P. Domingo
The study of both flame dynamics and combustion
instabilities, as for instance in aeronautical combustion
chambers, have benefited strongly from highly resolved
LES. The lengths in these systems are of the order of
half a meter. On the other hand, industrial combustion
systems featuring length of the order of 10 meters
cannot be addressed today with high resolution. A nonlinear downsizing procedure is discussed, which
preserves characteristic turbulent flame numbers
(Damkohler and Karlovitz), to simulate large furnaces
with high resolution. The method is first validated using
DNS and applied to a DeNOx SNCR system and a blast
furnace coal injector.
Development of an unstructured CFD solver for the
modeling of industrial furnaces
L. Romagnosi, J. Anker, K. Claramunt and C. Hirsch
NUMECA International, Belgium.
The modeling of furnaces can represent a challenging
task since multiple physical processes interact and a
realistic modeling of each of them is necessary to attain
an overall reliable prediction of the heat transfer,
combustion products and the pollutants. To model
industrial furnaces it is necessary to reliably model the
reactive flow as well as the conjugate and radiative heat
transfer. The formation of soot in furnaces can be
beneficial, since it can significantly enhance the
radiative heat transfer. However, since soot it is a
pollutant, attention must be paid that it is oxidized
before leaving the furnace. For environmental reasons
also the CO and the NOx emissions should be kept at a
minimum without compromising the efficiency of the
furnace.
In this study an unstructured, multiphysics-multipurpose CFD solver is presented for the modeling of
industrial furnaces. The numerical scheme as well as
different models available in the solver are explained.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP12: Industrial furnaces 79 Dedicated test cases for CHT in reactive flows,
modeling of radiative heat transfer, modeling of
combustion processes with large heat losses and
pollutants modeling will be used to assess and discuss
the suitability of the various submodels for the
modeling of furnace combustion. The overall modeling
framework is assessed on the glass melting furnace of
IFRF, the BERL natural gas burner and an industrial
furnace geometry comparing the computational results
with available measurement data.
CP13: Instabilities
Nonlinear stability study of a time-delayed
thermoacoustic system
Gas expansion and shear layer effects in turbulent
premixed flames
X. Yang1, A. Turan1 and S. Lei2
1
2
S. Schlimpert, A. Feldhusen, J. H. Grimmen, B. Roidl,
M. Meinke and W. Schröder
The University of Manchester, UK.
Bell Labs, Alcatel-Lucent, Ireland.
This work aims to investigate the various nonlinear
behaviours inherent in a time-delayed thermoacoustic
system, viz. the Rijke tube, using a continuation
approach. Unlike the conventional approach by
Galerkin method to investigate nonlinear behaviour, a
dynamic system is developed by spatially discretizing
the acoustic equations using standard finite difference
schemes in a Method of Lines manner. Temporal
evolution of pressure oscillations is studied to
demonstrate the interaction of acoustics and heat release
perturbations. Moreover, the subcritical Hopf and fold
bifurcations are captured to delineate the linear,
nonlinear stability boundary and limit cycles.
Furthermore, comparison of numerical calculations with
experimental data reveals that the current approach does
yield very good predictions.
Institute of Aerodynamics, RWTH Aachen University, Germany.
Combustion instabilities can cause serious problems
which limit the operating envelope of low-emission lean
premixed combustion systems. Predicting the onset of
combustion instability requires a description of the
unsteady heat release driving the instability. This study
focuses on the analysis of fully coupled two-way
interactions between a turbulent flow field and a
premixed flame by solving the conservation equations
of a compressible fluid in a fully coupled massive
parallel framework. Results of a turbulent jet flame will
be presented at varying gas expansion ratio to analyze
the impact of the hydrodynamic instability and shear
layer effect.
DNS investigation on thermoacoustic oscillation
characteristics of turbulent swirling premixed flame
in a cuboid combustor
K. Aoki, M. Shimura, Y. Naka and M. Tanahashi
Tokyo Institute of Technology, Japan.
To investigate the relation between fluctuations of
pressure, heat release rate and vortical motions, direct
numerical simulations (DNS) of hydrogen-air turbulent
swirling premixed flame are conducted and dynamic
mode decomposition (DMD) is applied to the DNS
results. DMD of pressure and heat release rate fields
and spectral analyses of vortical motions reveal that not
only the quarter wave mode of longitudinal acoustics
but also transverse acoustic modes, which interact with
periodic vortical motions, play important roles in
thermoacoustic instabilities. Acoustic energy budgets
are also investigated based on DMD results of the
source term in the acoustic energy equation.
Large eddy simulation of transverse modes in a
swirled kerosene/air combustor
A. Ghani1, T. Poinsot2 and L. Gicquel1
1
2
CERFACS, France.
IMF Toulouse, France.
Combustion instabilities due to longitudinal and
azimuthal modes have been addressed extensively in the
last years but less attention has focussed on transverse
modes. These modes create strong high-frequency
oscillations leading to high-pitched sound levels and
fast destruction of the system. The prediction of
transverse modes still remains a problem because no
theory is available. LES and acoustic solvers are used in
this work to study transverse modes in a swirled
kerosene/air combustor and propose a modified flame
transfer function framework adapted to these transverse
modes.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 80 CP13: Instabilities Acoustically induced vortex core flashback in a
staged swirl-stabilized combustor
Dynamical modeling of combustion instabilities in
liquid rocket engines
C. Lapeyre1, M. Mazur2, P. Scouflaire2, F. Richecoeur2,
S. Ducruix2 and T. Poinsot3
M. Gonzalez-Flesca, T. Schmitt, S. Ducruix
and S. Candel
1
CERFACS, France.
3
IMFT, France.
2
This paper describes a joint experimental and numerical
investigation of flashback mechanisms in a swirled
turbulent burner. This fully premixed combustor
terminated by a choked nozzle operating at 2.5 bars
shows a flame stabilized either within the combustion
chamber or flashbacked into the injection duct.
Flashback can occur naturally, or be triggered either
through acoustic forcing or self-excited thermoacoustic
instability. In the LES, self-excited oscillations reach
high levels rapidly, leading to flame flashback, as
observed experimentally. These results also suggest a
simple method to avoid flashback by using fuel staging,
which is then tested successfully in both LES and
experiments.
In an effort to predict combustion instabilities in liquid
rocket engines, a reduced order modeling is developed.
It relies on the expansion of the pressure field on the
eigenmodes of the system. This dynamical model
provides a state space description and accounts for the
main effects such as cavity coupling between dome and
chamber, damping, response of injectors to pressure
perturbations, combustion response to acoustic
oscillations or acoustic forcing. The model is used to
study a laboratory scale cold flow model as well as fullscale geometries. The ongoing work consists in the
simulation of a liquid rocket thrust chamber featuring
combustion instabilities under certain operating
conditions, with comparisons with experiments.
CP14: High performance computing / software engineering
Predictive fire simulations with the software ISIS
Scalable parallel and computationally-conservative
implementations of the conditional moment closure
model in large eddy simulations
C. Lapuerta, S. Suard, F. Babik and G. Boyer
IRSN, France.
The CFD software ISIS, developed at IRSN is based on
a coherent set of models that can be used to simulate
fires in mechanically ventilated compartments. This
fire model enables to perform predictive fire
simulations, either using accurate pyrolysis models
either global approaches for complex applications.
Specific boundary conditions are used to predict the
aeraulic behavior of the compartment for which the
ventilation network of the entire facility may be
computed by the IRSN zone code SYLVIA. The latest
developments concern two important topics in fire
modelling: large eddy simulation for reactive flows and
fire suppression by water mist. Documentations and the
open-source code are available at:
https://gforge.irsn.fr/gf/project/isis.
H. Zhang1, A. Garmory2 and E. Mastorakos1
1
2
Loughborough University, UK.
The scalable parallel and computationally-conservative
conditional moment closure (CMC) model in large eddy
simulations (LES) is implemented toward accurately
predicting the turbulence-chemistry interactions in
practical burners. Three parallel strategies are
developed to distribute the CMC workload: fully local
CMC, uniform round-robin and uniform adaptive
allocation based on the instantaneous chemistry
computation overhead. Their parallel efficiencies and
scalability are investigated for stiff/non-stiff chemical
mechanisms and different flame dynamics, e.g. swirling
non-premixed flames far from and close to blow-off.
The effects of CMC cell reconstruction and numerical
flux prediction in physical space are also studied, which
demonstrate the pronounced influence on calculating
critical combustion phenomena.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP14: High performance computing / software engineering A methodology for the integration of stiff chemical
kinetics on GPUs and application to the LES-PDF
simulation of a turbulent non-premixed flame
F. Sewerin and S. Rigopoulos
In numerical schemes for reacting flows, it is common
to isolate the chemical kinetics model by applying the
method of fractional steps. Here, we explore the
possible use of Graphics Processing Units (GPUs) in
order to accelerate the solution of the reaction step for
an implicit integration algorithm of order 5 (Radau5).
The performance of the novel GPU implementation is
evaluated for different reaction mechanisms, numbers
of grid points, time steps and convergence tolerances.
Moreover, strategies for parallelizing the reaction step
across a CPU-GPU pair are investigated and the
implementations are compared for an LES-PDF
simulation of the Sandia D flame.
Load balancing, dynamic repartitioning, and data
migration in turbulent reactors' simulation
P. Pisciuneri, E. Meneses, A. Zheng, A. Labrinidis,
P. Chrysanthis and P. Givi
University of Pittsburgh, USA.
Different approaches for maximizing the scalability of
parallel Lagrangian Monte Carlo solvers for turbulent
combustion are assessed. The issues of load balancing,
(re)partitioning, and data migration are considered via
81 three approaches:
Zoltan (Sandia National
Laboratories), Charm++ (University of Illinois at
Urbana-Champaign), and (P)ARAGON (University of
Pittsburgh). These approaches are compared in terms
of weak and strong scaling in simulation of turbulent
reactor via reduced order, finite-rate kinetics.
PoKiTT: an efficient, platform agnostic package for
thermodynamics, kinetics, and transport properties
in reactive flow simulations
N. Yonkee and J. Sutherland
Department of Chemical Engineering, The University of Utah, USA.
We introduce PoKiTT, a portable, lightweight library
for performing data parallel calculations of
thermochemical quantities commonly encountered in
turbulent reactive flow simulations. The capabilities of
PoKiTT include ideal gas property estimations,
thermodynamic polynomial evaluations (NASA and
Shomate), mixture average transport property
calculations (diffusion coefficients, viscosity, and
thermal conductivity), and detailed chemical kinetics
computations. PoKiTT uses Nebo, a domain specific
language,
to
provide
a
platform
agnostic
implementation which will be ready for future exascale
architectures. We demonstrate the performance benefits
of using PoKiTT over Cantera in the context of a PDE
solver for both CPU and GPU executions.
CP15: Kinetics
A modeling study of the low-temperature oxidation
of n-hexane, 2-methyl-pentane and 3-methyl-pentane
Z. Serinyel1, O. Herbinet2, R. Fournet2, V. Warth2
and F. Battin-Leclerc2
1
2
Kinetic modeling of the combustion of
2-methyl-2-butene
CNRS-ICARE, France.
CNRS-LRGP, France.
Detailed chemical kinetic mechanisms were generated
using software EXGAS for the oxidation of three
isomers of hexane: n-hexane, 2-methyl-pentane and 3methyl-pentane. These mechanisms considered a new
set of kinetic parameters for low temperature reactions
obtained using quantum calculations and were used to
simulate jet-stirred reactor experimental results.
Simulations showed satisfactory agreement for fuel
conversion, as well as the formation of many products,
including the isomers of cyclic ethers (with rings
including 3, 4, 5 and 6 atoms) which were
experimentally quantified. Incorporation of the new set
of rate constants into EXGAS improved model
predictions to an important extent.
C. Westbrook1, P.A. Glaude2, F. Battin-Leclerc2,
O. Herbinet2, O. Mathieu3 and E. Petersen3
1
LLNL, USA.
CNRS-LRGP, France.
3
Texas A&M University, USA.
2
2-Methyl-2-butene is an intermediate chemical species
produced during the combustion of branched alkanes
and a model molecule of the light alkenes chemistry. A
detailed kinetic mechanism has been developed and
validated against low and high temperature data
obtained in a jet stirred reactor and in a shock tube. 2methyl-2-butene produces mostly resonance stabilized
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 82 CP15: Kinetics radicals, which can slowly decompose into more
unsaturated products such as isoprene, 1,2-butadiene
and 2-butyne, or rather react by combinations with HO2
radical. The prompt decomposition of the
hydroperoxydes produced by these latter reactions
enhance the reactivity and can be explained the
formation of the main primary oxygenated products.
combustion model for light aromatics, have been
developed for each compound. Models predict well the
conversion of reactants and the formation of the main
products, such as aromatic tertiary tars, which are soot
precursors.
Comparison of the performance of several recent
hydrogen and syngas combustion mechanisms
C. Olm1, I. Zsély1, R. Pálvölgyi1, T. Varga1, T. Nagy2,
H. Curran3 and T. Turányi1
1
MTA Research Centre for Natural Sciences, Hungary.
3
Combustion Chemistry Centre, NUI Galway, Ireland.
2
A large set of experimental data was accumulated for
hydrogen and syngas combustion, including ignition
measurements in shock tubes and rapid compression
machines, concentration–time profiles in flow reactors,
outlet concentrations in jet-stirred reactors, and flame
velocity measurements. The 7000 datapoints cover wide
ranges of temperature, pressure and equivalence ratio.
The performance of 19 hydrogen and 16 syngas
combustion mechanisms was tested against these
experimental data, and the dependence of accuracy on
the types of experiment and the experimental conditions
was investigated. For both the hydrogen and syngas
combustion, these recently published mechanisms could
be sorted to the categories of good, average and poor
performers, but the performance of a mechanism
depended very much on the conditions where it was
applied. The influence of poorly reproduced
experiments on the overall performance was also
investigated.
Kinetic study of the combustion of phenolic tars
from biomass
M. Nowakowska, O. Herbinet, A. Dufour
and P.A. Glaude
CNRS-LRGP, France.
Tars are by-products of wood combustion and
gasification, which cause fouling, pollutant formation
and catalyst deactivation in processes. A significant
fraction of aromatic tars comes from lignin pyrolysis
mainly composed of guaiacol-type and syringol-type
units. The reactions of methoxybenzene (anisole) and
methoxyphenol (gaiacol) were studied as surrogates of
these phenolic tars from lignin. Detailed kinetic
mechanisms for the pyrolysis and oxidation, based on a
Transition state theory based semi-automatic
generation of surface reaction mechanisms
P. Kraus and P. Lindstedt
The present work focuses on developing a theoretical
framework of estimating Arrhenius parameters in
heterogeneous reaction systems, leveraging the UBIQEP method for estimating barrier heights, and a
combined collision/transition-state theory based method
for estimation of pre-exponential factors. The method is
validated for the case of partial ethane oxidation over
platinum, assessing the impact of key parameters
(oxygen/carbon ratio, inlet velocity, site density, heat
losses). The developed method reproduces experimental
data with an accuracy comparable to the collision
theory approach without the reliance on conjectural
experimental parameters, facilitating an efficient
generation
of
novel
heterogeneous
reaction
mechanisms.
Tabulation strategies of partially premixed
dimethyl-ether flames
S. Hartl, A. Zschutschke, D. Messig and C. Hasse
Dimethyl-Ether (DME) is a promising alternative
diesel-fuel. In contrast to methane, significant amounts
of intermediate hydrocarbons are found, both close to
the reaction zone and in the fuel-rich parts, where
DME-pyrolysis takes place. These differences are
important for combustion models, which are based on
flamelet-like approaches. These flamelet results are
usually tabulated for later retrieval in CFD-calculations.
In this work strategies are proposed for numerical CFDsimulations with tabulated chemistry. Here, we look at
the flamelet-progress-variable approach for DME
flames. Direct-chemistry CFD results of a partiallypremixed and a non-premixed DME-flame are validated
against experiments and further compared to different
tabulation approaches.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP16: Laminar flames 83 CP16: Laminar Flames
Transient response of a laminar premixed flame to a
radially diverging/converging flow
Diffusive-thermal instabilities in premixed flames:
stepwise ignition-temperature kinetics
M. Sahafzadeh1, L. Kostiuk2 and S. Dworkin1
L. Kagan1, I. Brailovsky1, P. Gordon2
and G. Sivashinsky1
1
2
University of Alberta, Canada.
Laminar flamelets are often used to model turbulent
flames. The libraries used for flamelets are typically
based on counter-flow, strained and curved laminar
flames under steady conditions. This research seeks to
further understanding of the current techniques in this
area by proposing a model for the less-considered
laminar flame dynamics of a cylindrically-symmetric
radially advected premixed flow. This model, which is
developed for a transient premixed flame, studies the
flame response to a diverging/converging flow, as the
flame grows or shrinks without being aerodynamically
strained in order to isolate these affects.
The analysis diffusional-thermal stability of rich
hydrogen-air combustion waves in model with
detailed kinetic mechanisms
1
2
The study is motivated by the observation that in
combustion of hydrogen-oxygen/air and ethyleneoxygen mixtures the global activation energy appears to
be high at low enough temperatures and low at high
enough temperatures, reflecting the complex nature of
the underlying chemistry. Numerical simulations of a
planar premixed flame propagation controlled by a
stepwise ignition-temperature kinetics (representing the
activation energy temperature-dependence) is carried
out. It is shown that, for all its schematic nature, the
diffusive-thermal model based on the ignitiontemperature kinetics reproduces successfully the basic
features of both cellular and pulsating instabilities
typical of low and high Lewis number mixtures.
Direct numerical simulation of circular expanding
premixed flames in a lean quiescent hydrogen-air
mixture: phenomenology and detailed
flame front analysis
V. Gubernov1, A. Korsakova1, A. Kolobov1, V. Bykov2
and U. Maas2
1
P.N. Lebedev Physical Institute of the Russian Academy of
Sciences, Russia.
2
Institute of Technical Thermodynamics, Karlsruhe Institute of
Technology, Germany.
The diffusional-thermal stability of rich hydrogen-air
combustion waves under ambient and elevated
pressures is numerically investigated. The model
includes the detailed transport and detailed kinetic
mechanism of hydrogen oxidation. Three different
kinetic mechanisms are employed: GRI3.0, Warnatz,
San-Diego. The critical conditions for the onset of
pulsating instabilities are found in the equivalence ratio
vs pressure parameter plane in each case. It is
demonstrated that the boundaries of stability differ
significantly depending on the specific kinetic
mechanism. This suggests that finding the critical
parameters for the onset diffusional-thermal instabilities
experimentally offers a new way for the verification of
kinetic mechanisms.
Tel Aviv University, Israel.
The University of Akron, USA.
C. Altantzis1, C. Frouzakis2, A. Tomboulides3
and K. Boulouchos2
1
2
3
Massachusetts Institute of Technology, USA.
ETH Zurich, Switzerland.
The combined effect of the hydrodynamic and the
thermodiffusive instability mechanisms on flames
propagating in gravity-free, quiescent mixtures leads to
the distortion of the smooth front by the appearance of
small-scale cellular structures, which in turn influence
the propagation dynamics and induce self-acceleration.
The evolution of a 3D spherical lean H2/air flame,
subject to the above-mentioned mechanisms, expanding
in a laminar environment is studied employing direct
numerical simulation with detailed chemistry and
transport. Detailed local analysis of geometric and
propagation characteristics of the flame together with
statistical analysis is used to elucidate the
phenomenology of cellularity and flame dynamics.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 84 CP16: Laminar flames Propagation of premixed flames in long narrow
channels from a closed end: transition from
constant speed to rapid acceleration
V. Kurdyumov1 and M. Matalon2
1
Department of Energy, CIEMAT, Spain.
Mechanical Science and Engineering, University of Illinois at
Urbana-Champaign, USA.
2
Propagation of a premixed flame in narrow channels
from the closed end is considered analytically and
numerically. An asymptotic approach shows that in
sufficiently narrow channels there are two distinct
solutions with a constant flame velocity corresponding
to slow and fast flames. The solution with the highest
velocity is unstable and therefore cannot be observed in
experiments. The two solutions merge when the channel
width is increased to a critical value, suggesting that the
slow propagation with a constant velocity changes to a
rapid exponentially-like acceleration. This has been
corroborated by direct numerical simulations. The
results thus provide a clear criterion for the conditions
and onset of exponentially-like acceleration in long
channels. Influence of heat losses and differential
diffusion (Lewis number) are also reported.
CP17: Real gas effects
Diffuse interface methods for diffusion flame from
subcritical to supercritical pressure
CP17: LES of transcritical LOx/GH2 injection
in a rocket engine
P. Gaillard, V. Giovangigli and L. Matuszewski
ONERA, France.
L. Matuszewski, P. Gaillard and V. Giovangigli
This study is focused on the subcritical to supercritical
regime transition encountered during the ignition of a
liquid-propellant cryogenic rocket engine. In this work,
both subcritical diphasic and supercritical monophasic
regimes are addressed with a diffuse interface method
allowing the investigation of the structure of a laminar
strained LOx/GH2 diffusion flame from subcritical to
supercritical pressure. Non-ideal thermodynamics and
multi-component transport may lead at low temperature
to instabilities and sharp interfaces separating
immiscible thermodynamical states even at pressure
higher than the critical pressure of the two propellant.
ONERA, France.
The absence of a dense potential core in
transcritical injection
Large eddy simulations of a naturally unstable
transcritical coaxial injector
D. Banuti and K. Hannemann
A. Coussement1, T. Schmitt1, S. Ducruix1, S. Candel1
and Y. Nunome2
German Aerospace Center (DLR), Germany.
Injection of cryogenic nitrogen into a chamber at
supercritical conditions has become a popular test case
for real gas CFD validation. However, there is a
systematic discrepancy: a measured immediate drop of
density upon entering the chamber could not be found
with theory or CFD. It is shown here that heat transfer
to the cryogenic injectant does take place and may
explain the exhibited behavior. In a numerical study,
different break-up modes could be reproduced by
varying heat transfer inside the injector. This thermal
break-up is essentially a new break-up mechanism,
strongly associated with pseudoboiling, a supercritical
state transition from liquidlike to gaslike.
Turbulent dispersion and mixing in the wake of the
injectors influence greatly the shape of the macroscopic
flame in liquid propellant rocket engines. This study is
focused on the effects on these phenomena of the stiff
density gradients arising from the transcritical LOx
injection. This work is based on a simplified multifluid
method which relaxes the mesh size constraints required
to describe the dense to dilute transition. This approach
is used to perform a Large Eddy Simulation of a typical
LOx/GH2 rocket engine injector.
1
2
In the context of liquid rocket combustion instabilities,
a naturally unstable test-bench from JAXA operating in
transcritical conditions is studied numerically, using the
AVBP-RG solver jointly developed by CERFACS and
EM2C. Two cases are considered: the first one
corresponds to experimentally stable injection
conditions, while the other one feature large pressure
oscillations in the combustion chamber. First numerical
results indicate a more dynamic behaviour of the
unstable case, in good qualitative agreement with
experimental data, compared with the stable case. The
current state of our simulations, a possible scenario
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP17: Real gas effects 85 explaining the presence of the instability and ongoing
analysis are presented.
Large eddy simulation of transverse acoustic activity
in a 42-injector rocket engine
A. Urbano1, L. Selle1, G. Staffelbach2, B. Cuenot2,
T. Schmitt3, S. Ducruix3 and S. Candel3
Oscillatory combustion in a sub-scale liquid
rocket chamber
T. Shimizu1, Y. Morii1, Y. Mizobuchi1, Y. Nunome1,
T. Tomita1, H. Kawashima1 and M. Hishida2
1
2
Ryoyu systems Corp., Japan.
Oscillatory combustion in a sub-scale liquid rocket
chamber is studied by a time-dependent numerical
analysis based on Large Eddy Simulation approach. The
dense fluid properties for H2/O2 combustion at supercritical pressure and the laminar flamelet model for
combustion, are implemented in an unstructured flow
solver developed at Japan Aerospace Exploration
Agency (JAXA). The obtained pressure oscillation
agrees well with the experiment. The amplitude of
pressure oscillation in the first longitudinal mode
increased when the inlet hydrogen temperature becomes
low. It is found that the flame length is the key to decide
whether an oscillatory combustion in the short sub-scale
chamber occurs or not.
1
2
3
IMFT, France.
CERFACS, France.
Large Eddy Simulations of a liquid-propellant rocket
engine are carried out. The configuration is an
experimental combustion chamber, called BKD and
operated by DLR, which comprises 42 coaxial injectors.
This engine exhibits high-frequency instabilities under
transcritical injection conditions. The aim of the study is
to gain understanding in the physical mechanisms that
trigger this transverse combustion instability, which is
also a high-performance computing challenge given the
number of injectors. The influence of operating
conditions is investigated on coarse (50 million
elements) and fine (500 million elements) meshes, both
under forced and self-excited conditions, for the first
transverse acoustic mode.
CP18: Gas turbine combustion
Numerical computation methods of hot gases
radiation in a turbofan combustion chamber:
performance comparison for a design process
Detailed analysis of light-round in an annular
multiple-injector combustor
R. Daviot and F. Loureiro
M. Philip, R. Vicquelin, M. Boileau, T. Schmitt
and S. Candel
SAFRAN - SNECMA, France.
In turbofan combustion chambers, hot gases radiation
plays a major role on the temperature reached by the
wall, and therefore on its life limit. During chamber
design, determination of this radiation by a numerical
computation must combine accuracy of solution and
speed of computation. This paper introduces a
comparison of the results achieved through a MonteCarlo method and a Discrete Ordinates one. A
comparative study has been made on an industrial
configuration concerning the influence of gases
radiation models such as 26 bands High Pressure Box
Model and Weighted Sum of Grey Gases on the
solution at different engine operating conditions.
Recent large eddy simulations of the ignition transient
in an annular combustor equipped with sixteen swirling
injectors have shown remarkable agreement with
experimental data in terms of flame topology and full
combustor ignition time. In the present study, a detailed
analysis of the mechanisms that control the light-round
sequence is carried out for two sets of operating
conditions. The ignition dynamics is characterized in
terms of flame tip trajectory, flame surface at resolved
and sub-grid scale levels, absolute and relative flame
displacement velocity. This is then used to analyze the
rate of displacement of the mean flame brush that
determines the overall ignition time.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 86 CP18: Gas turbine combustion Modelling chemistry in coupled combustor and
turbine CFD simulations
Direct numerical simulation of premixed flames
flashback in turbulent channel flows with
fuel stratification
R. Eggels
A. Gruber1, E.S. Richardson2 and J. Chen3
Rolls-Royce Deutschland, Germany.
1
The interaction between engine components, such as
combustor and turbine is getting more important. To be
able to model the combustor and turbine nozzle guide
vanes simultatenously a compressible reacting flow
capabiltiy is required. A method has been developed to
model the combustion process using the Flamelet
Generated Manifold approach, which has been extended
to model compressible flows where both the
temperature and pressure are varying. The changing
pressure and enthalpy and captured with an addional
controlling variable, assuming an isotropic expansion.
Furthermore, additional transport equations for the
enthalpy, NOx and CO are taking into account.
Additinal transport equations for NOx and CO taking
into account, while the NOx and CO chemistry is slow
compared to the change of pressure and temperature
within the NGV. The method has subsequently been
applied to an industrial gas turbine.
Combustor effusion cooling design parameters
analysis and modeling
N. Savary, R. Hervé and G. Cottin
Turbomeca, France.
Meeting the challenge of designing gas turbine more
money and fuel efficient requires among many other
aspects to design cheap combustor able to handle
increasing pressures and temperatures. Effusion cooling
is one of the best value for money combustor cooling
system as well as one of the most complex to model,
due to the high range of scales of the phenomena
involved. This numerical study explores the effect of
the typical design parameters on effusion cooling
efficiency. In particular, it proposes laws describing the
cooling performances as a function of hole diameter,
inclination and arrangement.
SINTEF Energy Research, France.
University of Southampton, UK.
3
2
Among the challenges in enabling lean pre-mixed
combustion technology for gas turbine applications,
accurate prediction of flame flashback in mixing ducts
stands out as a key requirement, in particular for highly
reactive fuels containing hydrogen. Complete
understanding of the complex physical processes that
control flashback is of fundamental importance in gas
turbine burner design and optimization. The present
study, based on computationally demanding and highly
resolved petascale direct numerical simulation (DNS),
focuses on providing unprecedented insight into the
turbulence-chemistry interaction that characterizes
flashback of preheated hydrogen-air flames inside of
mixing ducts. Bringing further previous experimental
and modelling work, the present DNS introduces fuel
stratification in the reactants' flow within the turbulent
channel configuration and has shown that the turbulent
flame shape, its propagation mechanism and its
combustion regime are all considerably affected by fuel
stratification.
Large eddy simulation of a two-stage liquid fueled
swirl burner: influence of injection strategies
B. Cheneau, A. Vié and S. Ducruix
Large Eddy Simulations of a two-stage swirling burner
fueled with liquid dodecane studied experimentally at
EM2C laboratory are performed. For a chosen lean
operating point at constant power, fuel proportion is
varied between the two injection devices, respectively
central hollow cone and peripheral multipoint
injections. Results highlight a dramatic influence on the
flame stabilisation processes: by varying the staging
factor, the flame takes various shapes associated with
different combustion regimes and dynamics, as well as
exhibiting hysteresis phenomena. The numerical
simulations provide additional information that help in
understanding the parameters and physics that trigger
bifurcation and cause the hysteresis loop.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. CP19: Fires 87 CP19: Fires
CFD simulations of fire-induced doorway flows in a
small scale enclosure
S. Suard, A. Koched, H. Pretrel and L. Audouin
IRSN, France.
CFD simulations of a fire in a small scale enclosure
with an open doorway, are presented. Three heat release
rates of 10.6, 15.5 and 21.7 kW, provided with a gas
burner, are numerically studied and compared to
temperature and velocity measurements at the doorway
and temperature measurements inside the enclosure.
Velocity measurements are performed using a SPIV
technique allowing a full comparison with CFD results.
For the three heat release rates, the simulation results
agree well with experimental measurements.
General flow patterns, provided by simulations, are
reported and supply useful information for
understanding enclosure fires.
Mathematical modelling of the interaction between
crosswind and aviation-fuel fire engulfing
a full scale aircraft
G. Wang and H.Y. Wang
Institut P’, Fluides-Thermique-Combustion, CNRS, ENSMA,
Université de Poitiers, France.
Large fully turbulent fires, which result as a
consequence of an aircraft accident, pose a severe
hazard to the occupants and cargo. This numerical study
focuses on the fire phenomenology associated with the
presence of a full scale aircraft immersed within a large
aviation-fuel fire in a moving fluid medium. Large
Eddy Simulation for the fluid dynamic equations of
three-dimensional elliptic flow is coupled with an Eddy
Dissipation Concept, allowing to the simulation of fire
growth and smoke (CO and soot) stratification in
progressively vitiated environment. The prediction
indicates that interaction between the large object and
fire environment combined with the influence of wind
conditions affects dramatically location of the
continuous flame zone and heat flux distribution.
formed by the vegetation and the surrounding
atmosphere, in assimilating the vegetation as a sparse
porous media and performing a homogenization-like
procedure. After a detailed presentation of the physical
and mathematical model, some numerical simulations
are presented, illustrating various configurations of
propagation of fire (surface fire, backfire, counter fire
…), in various ecosystems (grass, shrubs), and under
various external conditions (slope, wind). The problem
of fire safety engineering in the wildland urban
interface (WUI) is also treated.
LES modelling of burning wildland fuels
M. El Houssami1, A. Lamorlette2, D. Morvan2
and A. Simeoni1
1
2
University of Edinburgh, UK.
Thermal degradation and ignition of wildland fuels is
simulated using a multiphase formulation. The physical
model is implemented in FireFOAM, a Large Eddy
Simulation (LES) solver for fire application, derived
from the C++ object-oriented toolbox OpenFOAM.
Fuel degradation is represented in three different steps:
water evaporation, gas pyrolysis and char combustion.
Several strengths and weaknesses of the current submodels (combustion, radiation, convection and
turbulence) are identified by comparing simulations to
experimental results, such as mass loss rates and heat
release rates of burning samples of dry pine needles
exposed to a radiative heat flux.
How simulating the behaviour of wildland fires?
D. Morvan
This communication demonstrates in what manner the
behaviour of wildland fires can be simulated from a
multiphase formulation. This approach consists in
calculating the time evolution of the coupled system
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015. 88 CP19: Fires Evaluation of a sensor-driven wildlandfire spread
modeling strategy using the FireFlux experiment
1
1
1
1
C. Zhang , M. Durand , W. Tang , M. Gollner , A.
Trouvé1, M. Rochoux2, S. Ricci3, B. Cuenot3, J. Filippi4
and C. Clements5
Two and three dimensional numerical simulations
of wildland fires
A. Lamorlette and D. Morvan
1
Department of Fire Protection Engineering, University of Maryland,
USA.
2
Meteorological Research Division, Environment Canada, Canada.
3
CERFACS, SUC-URA1875, CNRS, France
4
Laboratoire Sciences Pour l’Environnement, CNRS and Université
de Corse, France.
5
Department of Meteorology and Climate Science, San Jose State
University, USA.
The objective of this project is to develop a data-driven
simulator capable of forecasting wildfire spread
dynamics. The prototype simulator features the
following components: a fire propagation solver that
adopts a regional scale viewpoint, treats wildfires as
propagating fronts, and uses a description of the local
rate of spread of the fire as a function of vegetation,
topographical and meteorological properties; a series of
observations of the fire front position; and a data
assimilation algorithm based on an ensemble Kalman
filter. The prototype simulator is evaluated in a
validation study corresponding to a controlled
grassland-fire field experiment called FireFlux.
Wildland fire propagation are simulated using a
multiphase formulation. The physical model is
implemented in FireFOAM, a Large Eddy Simulation
(LES) solver for fire application, derived from the C++
object-oriented toolbox OpenFOAM. Two dimensional
and three dimensional simulations are carried out in
typical grassfire conditions, for different wind intensity,
in order to enlighten three dimensional effects on both
fire rate of spread and fire residence time. The role of
radiation and convection ahead of the fire front is also
evaluated, allowing to discuss the assumptions usually
admitted for large scale fire modelling.
15th International Conference on Numerical Combustion, Avignon, France, April 19th – 22nd, 2015.

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