Propagation of a flame through a stratified charge combustion chamber

Flame propagation through stratified media is examined with a numerical model of chemically reactive flow in combustion systems. The model includes a detailed reaction mechanism for methane combustion and an implicit Eulerian difference equation form for the hydrodynamics. Calculations of flames propagating through spatially uniform and stratified media are compared. Results are presented which indicate that hydrodynamic factors can have a significant effect on the energy production rates, pressure rise rates, and unburned fuel concentrations for all models. For the stratified charge models it was found that CO and NO_x production rates were significantly lower than for uniform charge models. Significant amounts of unburned fuel are found near the combustion chamber wall, even in some of the stratified charge models, so that reaction quenching at the wall may be important even in the stratified charge cases. Calculations are presented which predict improvements in fuel efficiency and decreases in pollutant formation, resulting from changes in fuel stratification and compression ratio.