Effects of Nozzle Hole Diameter and Injection Pressure on Fuel Adhesion of Flat-Wall Impinging Spray 2019-01-2246

In direct injection spark ignition (DISI) engine, it is difficult to avoid the spray impingement of fuel on the cylinder wall and piston head, which is a possible source of hydrocarbons and soot emission. The injector nozzle geometry and injection pressure are essential components for the spray atomization and mixture formation. For better understanding the effects of injector hole diameters and injection pressure, the fuel spray and adhesion on a flat wall by different mini-sac injectors with a single hole was examined in this study. A flat-wall made of quartz glass was used as the impingement plate. Refractive Index Matching (RIM) method was applied to measure the thickness of fuel adhesion on the wall. All the cases performed in constant high-pressure chamber were under high temperature condition considering the real gasoline engine condition. Time-resolved behaviors of the fuel adhesion as well as adhesion mass, area and thickness were discussed. Results show that the decreased nozzle hole diameter and increased injection pressure reduce the fuel adhesion mass, area and thickness. Moreover, the enlarged nozzle hole diameter and injection pressure improve the uniformity of the adhesion thickness.