Large eddy simulation of combustion process in a boosted and downsized gasoline engine

The intake, spark ignition and combustion process in a boosted downsized gasoline engine was simulated using LES. The effect of turbulence fluctuation above the subgrid length scale on the combustion process in combustion chamber was assessed. A k-equation SGS model was implemented in the KIVA-Chemkin code. Progress in early flame kernel growth was predicted with the DPIK ignition model. Turbulent flame propagation was described using the level set G-equation combustion model. A 47-species, 142-reactions PRF mechanism was adopted to predict the auto-ignition of the end gas in front of flame front and the post-oxidation process in the burned zone. Under high load operation conditions, the simulation results agree with the experimental data for both normal combustion and knocking combustion. The simulation captured the turbulent flame propagation, flame wrinkles and end gas auto-ignition during the spark ignition process.