MS3-5 Coupling of G-Equation Combustion Model with Reduced Chemical Kinetics for Knock Prediction in DISI Engines: Combustion and Knock Prediction in Gasoline Engines (MS …

In this work the G-equation combustion model has been implemented into StarCD code and coupled with an ODE-kinetic solver for predicting knock in a DISI engine based on the Shell autoignition model. The combustion model has been validated for selected engine operating points. A mesh sensitivity analysis highlighting the influences of mesh topology and grid type (hexahedral and polyhedral) is presented. To account for sensitivities of octane number and EGR ratio on knock behaviour, the governing parameters of the Shell model have been identified and optimized with the help of DoE. The knock models presented here can be operated in both a passive and an active way. The validation of both knock models with respect to temporal and local knock onset is done with fibre optical spark plug measurements and evaluation of statistical results of pressure trace analysis for a direct-injection spark-ignition engine. Both passive and active knock model approaches are compared in regards of pros and cons as well as engine performance. Finally the necessity of thin turbulent flame brushes realized with G-equation combustion model and their relevance for knock simulation is discussed.