Prediction of knock onset and the autoignition site in spark-ignition engines

Abstract

A three-dimensional model of knock is developed to predict knock occurrence and the autoignition site in spark-ignition engines. A premixed turbulent combustion model, which falls within the flame area evolution category, and a flame wall quenching model are applied to simulate flame propagation. A reduced kinetic model is used to simulate autoignition in the unburned gas region. Engine experiments are performed to calibrate the reduced kinetic model and to verify the results of this modelling. A spark plug integrated pressure transducer and 11 ion probes are installed in the cylinder head to detect knock occurrences, flame arrival angles and autoignition sites. The model predictions show good agreement with the cylinder pressures, flame arrival angles, knock occurrences and autoignition site of the engine experiments with the variations in spark timing.