A THEORETICAL MODEL FOR TWO-PHASE FUEL INJECTION IN STRATIFIED CHARGE ENGINES

A computational model is presented which can deal with a variety of fluid-dynamic problems associated with injection of fuel into engine chambers. The model differs from previous ones in that it depends more on the basic equations of fluid dynamics and less on experimental correlations. It has been applied to a wide variety of gas jet injection problems examining the effects on the flow field and fuel/air mixing caused by variations in injection velocity, mass flow rate, air swirl, and injector location. Increased jet velocity markedly enhances air/fuel mixing; increasing the air swirl rate enhances the mixing to a lesser degree. Slower mixing results when the injector is located at the chamber wall than when it is located close to the chamber axis. Use of the spray droplet model has identified the physical processes characterizing the evolution of such sprays. The gas jet and the droplet jet are qualitatively and quantitatively different, and the conventional use of gas jet models in environments which are not close to the thermodynamic critical point is probably not appropriate in most cases.