Three-dimensional calculation of unburned hydrocarbon oxidation in spark-ignition engines

A 3-dimensional simulation method has been developed to predict the oxidation rate of unburned HCs in the combustion chamber and exhaust port of spark-ignition engines. A computational mesh with a moving grid for valve and piston motions has been constructed for a commercial 4-valve spark-ignition engine. A premixed turbulent combustion model and a flame wall-quenching model have been applied. In order to predict the oxidation of the unburned HCs, a 4-step oxidation model is used and the coefficients of the model have been modified for the engine oxidation environment using the results from a full chemical kinetic mechanism. The mixing of unburned hydrocarbon and burned gases is examined, and the oxidation rates within the cylinder and the exhaust port are investigated.