FUNDAMENTAL STUDY ON DIRECT-INJECTION STRATIFIED CHARGE COMBUSTION.

An experimental study has been made on stratified charge combustion which may possibly realize lean combustion in a spark ignition engine. In order to simulate charge stratification, methane was injected into a constant volume vessel, and its temporal and spatial concentrations were measured using a hot wire probe. Thus, fuel distribution maps were drawn throughout the vessel for successive timings after fuel injection. Then, ignitability was determined for various spark plug locations and related to the measured stratified charge. The results have shown that a local mixture exceeding its flammable limit for mean fuel-air ratio can be ignited with a proper turbulence of fuel concentration and that for fast burning of the whole charge, spark ignition should be made at a downstream point of the fuel jet.