0D/3D Simulations of Combustion in Gasoline Engines Operated with Multiple Spark Plug Technology

A simulation method is presented for the analysis of combustion in spark ignition (SI) engines operated at elevated exhaust gas recirculation (EGR) level and employing multiple spark plug technology. The modeling is based on a zero-dimensional (0D) stochastic reactor model for SI engines (SI-SRM). The model is built on a probability density function (PDF) approach for turbulent reactive flows that enables for detailed chemistry consideration. Calculations were carried out for one, two, and three spark plugs. Capability of the SI-SRM to simulate engines with multiple spark plug (multiple ignitions) systems has been verified by comparison to the results from a three-dimensional (3D) computational fluid dynamics (CFD) model. Numerical simulations were carried for part load operating points with 12.5%, 20%, and 25% of EGR. At high load, the engine was operated at knock limit with 0%, and 20% of EGR and different inlet valve closure timing. The quasi-3D treatment of combustion chamber geometry and the spherical flame propagation by the 0D SI-SRM enabled for estimating the impact of number of spark plugs on the combustion progress and the risk of knock occurrence. Application of three spark plugs shortened significantly the combustion process. When the engine was operated at knock limit and with 20% EGR, combustion duration was similar to that of engine operation without EGR and with one spark plug. Overall, the results presented demonstrate that this method has the potential to support early stages of engine development with limited experimental data available.