Numerical Simulation of Cycle-to-Cycle Variation for Knock Prediction in a Turbocharged Spark Ignition Engine

In this paper a novel approach to mimic through numerical simulation Cycle-to-Cycle (CCV) Variations of the combustion process of Spark Ignition (SI) engines is described. The proposed methodology allows to reproduce the variability in combustion which is responsible for knock occurrence and thus to replicate the stochastic behaviour of this abnormal combustion phenomenon. On the basis of the analysis of a comprehensive database of experimental data collected on a typical European downsized and turbocharged SI engine, the proposed approach was demonstrated to be capable to replicate in the simulation process the same percentage of knocking cycles experimentally measured in light-knock conditions, after a proper calibration of the Kinetics-Fit (KF), a new phenomenological knock model which was recently developed by Gamma Technologies. Finally, the capability of the proposed methodology, coupled with the usage of the KF knock model, to correctly identify the Knock Limited Spark Advance (KLSA) on the basis of the CCV-replicating model was assessed over a wide range of different operating conditions, thus confirming its reliability and robustness.