EFFECTS OF CROSS-FLOW ON FUEL SPRAY INJECTED BY HOLE-TYPE INJECTOR FOR DIRECTINJECTION GASOLINE ENGINE

摘要

The quality of fuel spray plays a vital role in the combustion and emission formation processes in a directinjection (DI) gasoline engine. To fundamentally understand the effects of the airflow on the fuel spray in the combustion chamber in a DI engine the characteristics of the fuel spray in a uniform cross-flow field were experimentally investigated in this study. The fuel was injected by a valve covered orifice nozzle for a DI gasoline engine into an optically accessible rectangular wind tunnel under room temperature and pressure, in which the fuel injection was perpendicular to the orientation of the cross-flow. The velocity of the cross-flow varied from 0 to 9.2 m/s while the injection pressure was 5 and 10 MPa. When the velocity of cross-flow is low, the vertical penetration increases with increasing the injection pressure, while in the case of the horizontal penetration, the distance increases with an increase of the injection pressure and velocity. Empirical correlations were deduced for the temporal variation of vertical penetrations as well as the variation of spray profile in the upstream side with distance along the cross-flow orientation. The velocity of cross-flow plays a more significant role than the injection pressure on the fuel spray in a cross-flow field. Velocity distributions were measured by a particle image velocimetrysystem, and the results show that the horizontal component of the velocity of the atomized droplet was even higher than that of the cross-flow in the lower region of the spray.