Optical Investigations of Fuel-Mixture Generation at Cold Start Conditions of SI-Engines in Consideration of Heat Loading

The paper presents laser optical investigations of mixture formation at negative pressure conditions, typical for throttle-controlled SI engines. A high pressure injector as well as a low pressure injector is used to estimate the behavior of different fuels (premium gasoline and ethanol) at different negative ambient pressures. The objective is to show the potential of combining the better evaporation due to less ambient pressure with a heat loading effect due to variable inlet timing especially for the use of ethanol.