The Effect of Ambient Gas Temperature and Density on the Development and Wall Impingement of High-Injection-Pressure Diesel Fuel Sprays

Abstract

An investigation of the effect of ambient gas temperature and density on diesel fuel spray penetration, spray angle, and wall impingement at an injection pressure of 75–134 MPa was conducted in a constant-volume bomb with a reconstructed Cummins PT fuel system by using a high-speed photographic technique. The results show that penetration does not increase monotonically with injection pressure, and ambient temperature has more effect on a high-pressure spray than on those with conventional pressures. With the high temperature, the penetration of a high injection pressure spray is reduced a bit, while the spray angle increases obviously. When the high-pressure spray impinges on a wall at ordinary temperature, the rebounding droplets can hardly be seen, but at higher wall temperature, a cloud of dense spray will be observed near the wall, and sometimes a vapor layer will be formed between the spray and the wall. Based on experimental results, an empirical formula considering the effects of both the ambient temperature and injection pressure is presented.