A simplified mechanism for the prediction of the ion current during methane oxidation in engine-like conditions

Abstract

This paper outlines a simplified mechanism for methane oxidation for modelling the ion current in internal combustion engines. The mechanism was used to simulate a laminar flame at elevated pressures and equivalence ratios typical of a spark-ignited engine. The predicted flame speed was found to be accurate between equivalence ratios of 0.9 and 1.1 at pressures of 10atm and 20atm. Good agreement was found between published experimental results and numerical results for the flame composition of atmospheric laminar flames at different equivalence ratios.Experimental results of the ion current and chamber pressure are presented for the combustion of methane in a constant volume chamber at different initial pressures and equivalence ratios. The experimental data obtained were used to validate the mechanism developed. The prediction of chamber pressure and ion current timing were found to be accurate, while there were some inaccuracies in the prediction of the ion current’s magnitude.