Spray Layout And Optimization In Two-cylinder Two-stroke Direct Injection Horizontally-opposed Gasoline Engine

The benefits of two-stroke engine are high power, few parts and simple structure, but,BSFC and emission are disadvantage. In recent years, vehicle engine require lower andlower BSFC and fewer and fewer emission, so two-stroke engine are used less. Buttwo-stroke engine have more potential. stroke engine have simple structure, few parts,light mass, small shaping and high power density, all this benefit make two-stroke enginefit for Hybrid Electric Vehicle and Pure Electric Vehicle Range-Extended.Why two-stroke engine have the defect of high BSFC and bad emission? The mainreason is scavenging. In the process of scavenging, the unburned gasoline run off fromcylinder to exhaust port. If gasoline direct inject in cylinder, we can control the inject timeto avoid the Unburned gasoline loss, we can inject the gasoline when exhaust port shutdown, so the question will be solved.The main content of this study is about the layout and optimization of two-strokedirect injection engine’s spray in the cylinder. First, based on the deep researched spraycharacteristics of fuel injector with laser testing methods, a simplify cylinder model shouldbe established and be used for the layout of spray through the processed spay image. Onthis basis, the distance between the spray and cylinder wall should be further analysis forthe optimization of the spray layout.According to the optimization of the single working conditions motor in this study,the spray in the central of the cylinder is the appropriate selection, because the spray iswell-distributes in the cylinder and a enough distance to the cylinder wall should beexisted for the wetted wall risk reduction.Based on the optimization results, the prototype engine has been developed and tested. During the testing, through adjustment of the ignition injection timing andoptimization of the engine performance, the testing results is very close to the results ofthe spray optimization, The feasibility of the layout optimization of two-stroke directinjection engines spray in the cylinder was verified.