Multiple Spark Plug Approach: Potential for Future Highly Diluted Spark Ignited Combustion

Numerical simulations and experimental works have been carried out to analyze the impact of multiple spark plug technology (MSP) on diluted combustion processes of spark ignition (SI) engines. Calculations were carried out using a zero-dimensional (0D), probability density function (PDF)-based stochastic reactor model for spark igni-tion engines (SI-SRM). The capability of the SI-SRM to account for the effects of MSP operation has been verified via comparison to three-dimensional (3D) computa-tional fluid dynamics (CFD) simulations that were carried out for the same engine and operating point. The quasi-3D treatment of the combustion chamber geometry by the 0D SI-SRM enabled simulating a 3D character of the flame propagation. The influ-ence of the number of spark plugs and their locations on the combustion progress has been analyzed. The detailed chemistry consideration by the SI-SRM enabled to access the risk of knock occurrence. The application of three spark plugs has short-ened significantly the combustion process. This, for engine operated at knock limit, and with 20 % of exhaust gas recirculation (EGR), has led to the combustion duration similar to the engine operated without EGR and with one spark plug – but with clearly improved combustion phasing, leading to more efficient engine operation in knock-restricted map areas.
Furthermore, the proposed simulation method has proven to be relevant for the ap-plication at early stages of engine concept development with limited experimental data available.