Interactions of Direct-Injection Fuel Sprays with In-Cylinder Air Motions

Abstract

An experimental investigation of the effects of injector type and orientation, engine speed, incylinder air swril, compression pressure, and fuel type has been conducted in motored visualization engines. A fuel-spray visualization system has been developed and utilized to obtain high-speed stroboscopic movies of the injection and penetration events. Significantly different interactions between the fuel spray and the in-cylinder air motions were found to result from changes in airswirl ratio, nozzle geometry and injection timing. The maximum spray-tip velocity was found to occur downstream from the injector tip for all conditions tested. For applications requiring minimum fuel-spray penetration, trhe impinging-jet injector was found to be the most promising candididate.