Unsteady flows inside the piping systems of Internal Combustion

Equipe Energétique des Moteurs à Combustion Interne
Laboratoire de Mécanique des Fluides – UMR CNRS 6598
Unsteady flows inside the piping systems of Internal Combustion Engines:
1-D simulation modeling and experimental validation
David Chalet, Pascal Chessé, Michel Violleau
2002 Fall Technical Conference of the ASME Internal Combustion Engine Division
New Orleans, Louisiana, September 8-11, 2002
The main difficulty for the one-dimensional simulation of pressure waves in the inlet
and exhaust systems of Internal Combustion Engines consists in the modeling of singularities
(area changes, bends, junctions, etc.). The models presented in the literature are based on the
behavior of the singularity in steady flow. However the pressure losses due to the wave
propagation are different from those obtained in stationary flow. The authors’ objective is to
propose models with a better precision based on the non steady study of the singularities
which can be found in Internal Combustion Engines. Specifically, this paper presents the
investigation of the pipe wall friction factor and the sudden contraction area. The first step
consists in studying the behavior of pressure waves through pipes with the Fluent CFD code.
Next, a model parameterized with the Reynolds number is proposed for the pipe wall friction
factor while another one with the Mach number is proposed for the sudden contraction area.
These models are included in a 1-D simulation code. Finally, in order to evaluate the accuracy
of the simulation program, the models are compared with experimental data. The results show
a satisfactory agreement between model predictions and experimental measurements.
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