Prediction of Unburned HCs by Using Three-Dimensional Combustion Simulation in Spark Ignition Engines

Abstract

Three dimensional combustion simulation tools with the flame propagation model Universal Coherent Flamelet Model (UCFM) has been applied to SI lean burn combustion to study the influence of equivalence ratio on the amount of unburned fuel. Unburned HCs from piston-cylinder crevices were taken into consideration by using a calculation grid incorporating the actual crevice volume and shape. The oxidation of unburnt fuel from crevice volume and wall quench was enabled to be predicted by applying an autoignition model to post-flame phenomena. The calculation results show the general tendencies for the total amount of unburned HCs and their distribution in the combustion chamber.