FUNDAMENTAL STUDIES ON DIRECT INJECTION STRATIFIED CHARGE COMBUSTION IN A CONSTANT VOLUME BOMB.

In spark ignition engines, direct injection stratified charge combustion system is an anticipated alternative to conventional engines. Because it has some advantages of high thermal efficiency, multi-fuel combustion capability and low carbon monoxide and nitric oxide emissions. It has, however, an unfavorable feature of high unburned hydrocarbon emission levels especially during light-load operations. In this paper, fundamental studies on this system were carried out using a pancake typed constant volume bomb. Some features of combustion behavior were made clear for several overall equivalence ratios. Then, two-points ignition system and locally homogenized stratified charge combustion system were examined for the purpose of shortening combustion duration and reducing unburned hydrocarbon emissions. The stratification and mixing process of fuel jet and combustion process were observed by schlieren photography. And variation process of local fuel concentration was measured by concentration probe.