Gasoline Compression Ignition has been widely studied in recent years. The in-cylinder stratified charge in gasoline Partially Premixed Compression Ignition (PPCI) can extend the high load range with lower pressure rise rate than Homogeneous Charge Compression Ignition (HCCI). However, it is still not clear that whether there is flame propagation in the gasoline compression igntion mode and how the flame propagation influences the combustion process and pollution formation. In order to investigate the effect of flame, several gasoline compression ignition cases, including the single-stage and two-stage heat release processes, are simulated with the KIVA-3V Release 2 code in this study. The G-equation is employed to account for flame propagation, and the reduced i-octane/n-heptane mechanism is used to handle the chemical reactions.
The results show that the flame propagation exists in the combustion process and it can accelerate the heat release slightly. However, the effect of the flame propagation on the whole combustion process is not significant. In the two-stage gasoline combustion, more flame front can be found during the second combustion process. When the flame propagation is considered, the emission results are better predicted, even though the magnitude of NOx is higher than the experimental data.