Effects of Piston Crevice Geometry on the Steady-State Engine-Out Hydrocarbons Emissions of a S.I. Engine 952537
This study investigated the effects of piston Crevice geometry on the steady-state engine-out hydrocarbons (HC) from a Saturn DOHC four-cylinder production engine. A 50% reduction in top-land height produced about 20-25% reduction in HC emissions, at part loads. The effect of top-land radial clearance on HC emissions was found to depend on the value of top-land height, which suggests a complex relation between flame propagation in the piston crevice and crevice geometry. For idle, increasing top-land clearance resulted in an increase in HC emissions. This trend is opposite to the trend at part load. A simple model was developed which predicts surprisingly well the contribution of piston crevices to HC emissions. It was estimated that for the test engine, piston crevices contribute about 50% of the engine-out hydrocarbons. Finally exhaust gas recirculation appears to decrease the sensitivity of HC emissions to crevice dimensions.
Citation: Alkidas, A., Drews, R., and Miller, W., "Effects of Piston Crevice Geometry on the Steady-State Engine-Out Hydrocarbons Emissions of a S.I. Engine," SAE Technical Paper 952537, 1995, https://doi.org/10.4271/952537. Download Citation
A. C. Alkidas, R. J. Drews, W. F. Miller
General Motors Research and Development Center
1995 SAE International Fall Fuels and Lubricants Meeting and Exhibition
Emission Control and Fuel Economy for Port and Direct Injected SI Engines-PT-91, SAE 1995 Transactions: Journal of Engines-V104-3