Experimental Investigations on Fuel Spray and Impingement for Gasoline Direct Injection Engines

Spray-wall impingement is a widespread phenomenon applied in many fields, including spray-wall cooling system, spray coating process and fuel spray and atomization in internal combustion engines. In direct-injection spark ignition (DISI), it is difficult to avoid the fuel film on the piston head and cylinder surfaces. The wet wall caused by impingement affects the air-fuel mixture formation process, which finally influence the subsequent combustion efficiency and performance. Therefore, the fuel spray and impingement under gasoline engine-like conditions were characterized. Mie scattering technique was applied to visualize the spray evolution and impingement processes in a high-pressure and high-temperature constant chamber. Meanwhile, the adhered fuel film on the wall was measured by refractive index matching (RIM) under non-evaporation and evaporation conditions considering the effects of different injection pressures, ambient pressures and ambient temperatures. Additionally, the fuel film formation and evaporation evolution models were proposed with the help of these mechanisms.