Development of flame propagation model for SI engine and its application to knoking prediction

Abstract

Combustion in IC engines involves very complicated phenomena, which are strongly affected by engine speed, load and turbulence intensity. The aim of this study was to develop a flame propagation model and a knock prediction technique applicable to various engine oparating conditions. A new flame propagation model (UCFM) has been developed that improves the Coherent Flamelet Model (CFM) by considering flame growth both in terms of the turbulent flame kernel and laminar flame kernel. A knock prediction model was developed by implementing the Livengood-Wu integral as the autoignition model in the flame propagation model. The combined model allows evaluation of both where and when autoignition occurs in a real shape combustion chamber. The three-dimensional calculation results indicate the general tendency for the pressure history and the location where autoignition occurs in the combustion chamber.