The spray characteristics of a multihole gasoline direct injection system have been investigated through a visualization technique. Further, the influences of ambient pressure, injection pressure, and injector mounting angle on the spray behavior were studied. In particular, the impingement of the sprayed gasoline on the piston surface was visualized and analyzed. The development of a free shear layer in which mixing of air and sprayed fuel occurs has been observed. The results show that as the injector mounting angle and ambient pressure are reduced, the concentration of atomized fuel increases near the spark plug.

spray, injection pressure, piston surface, multihole GDI injector.