An Experimental Study on Mixture Formation Process of Flat Wall Impinging Spray Injected by Micro-Hole Nozzle under Ultra-High Injection Pressures 2008-01-1601

Increasing injection pressure and decreasing nozzle hole diameter have been proved to be two effective approaches to reduce the exhaust emissions and to improve the fuel economy. Recently, the micro-hole nozzles and ultra-high injection pressures are applicable in commercial Diesel engines. But the mechanism of these two latest technologies is still unclear. The current research aims at providing information on the spray and mixture formation processes of the micro-hole nozzle (d=0.08mm) under the ultra-high injection pressure (P_inj=300MPa). The flat wall impinging sprays were focused on and the laser absorption-scattering (LAS) technique was employed to obtain the qualitative and quantitative information at both atmospheric and elevated conditions. The spray parameters were collected, the mixing rate was discussed, and the effects of various parameters on mixture formation were clarified. Experimental results demonstrate that the combination of the micro-hole nozzle and the ultra-high injection pressure is very effective to increase the mixing rate. The high ambient gas density has a strong positive influence on the uniform lean mixture preparation.