Influence of the wall temperature on the mixture preparation in DI gasoline engines

Abstract

Spray-wall interaction and liquid film models are developed, validated and used to provide better understanding of fuel distribution in a DI gasoline engine with a 'wide' concept. Numerical calculations including combustion were performed to study the influence of piston temperature on mixture preparation under stratified charge operating conditions. During cold operation or cold start, up to 25% of injected mass forms a liquid film on the piston bowl bottom. This largely affects the combustion efficiency. Increasing piston temperature decreases the gasoline unburned film amount. No significant liquid film remains on the piston when its temperature exceeds the mean of the boiling and Leidenfrost temperatures. This result agrees well with the available experimental observations which confirm the absence of liquid film when piston temperature exceeds 460 K.