A Comparison between Two Combustion Models for Premixed Charge Spark Ignition Engines

In this paper, two advanced combustion models for premixed charge spark ignition (SI) engines have been analysed, implemented and validated. This study arises from the need to have a more reliable and accurate computational tool for analysing the physical and chemical phenomena during the combustion process in SI engines. The Local Equilibrium Characteristic Time (LECT) model and the Coherent Flame Model (CFM) have been considered. These sub-models have been implemented in a full 3-D model that can simulate reciprocating and rotary engines. Simulations of the combustion process have been carried out in a premixed charge spark ignition engine in a relatively simple geometry. The combustion chamber has an axisymmetric geometry with the spark plug located on the engine head along the axis. A parametric study of the two combustion models has been carried out and, by changing the initial values of some physical quantities, it is shown that correct trends are obtained. The sensitivity of the results to model parameters shows a strong dependence when CFM is used.