Fuel Motion and Pollutant Formation in Stratified Charge Combustion

The concept of charge stratification is examined, using a numerical model for fluid mechanics and chemical kinetics. Initially homogeneous and stratified charge cases are discussed and compared, and simplified global rate expressions for the chemical reactions are compared with a detailed reaction mechanism. Results computed for the stratified models indicate that the fuel can be completely burned before it reaches the walls of the combustion chamber, effectively eliminating wall quenching as a source of unburned hydrocarbon emissions. However, volume flame quenching appears to result in unacceptably large amounts of unburned fuel in the stratified models.