Fuel-Spray Characteristics of High Pressure Gasoline Injection in Flowing Fields

The direct infection into the cylinders has been regarded as a way of the reduction in fuel consumption and pollutant emissions. The spray produced from the direct injector is of paramount importance in GDI (Gasoline Direct Injection) engines in that the primary atomization process must meet the requirement of quick and complete evaporation and combustion especially to prohibit the excessive HC emissions. The interaction between air flow and fuel spray was investigated in a steady flow system embodied in a wind tunnel to simulate the variety of flow inside the cylinder of the GDI engine. The direct Mie scattered and Shadowgraph images presented the macroscopic view of the liquid sprays and vapor fields. The velocity and particle size of fuel droplets were investigated by Phase Doppler Anemometer (PDA) system. The processes of atomization and evaporation with a GDI injector were observed and consequently utilized to construct the data-base for the spray and fuel-air mixing mechanism as a function of the flow characteristics.