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Effect of Injection Pressure and Nozzle Hole Diameter on Mixture Properties of D.I. Diesel Spray
Published May 01, 2006 by Society of Automotive Engineers of Japan in Japan
Event: JSAE Spring Conference
The spray and mixture properties are the primary factors which control the fuel-air mixing formation and subsequent combustion processes in D.I. diesel engines. The quantitative information on the mixture concentration distributions inside a fuel spray is of significant importance in in-depth understanding the spray structure and mixture properties. In this study, the Laser Absorption Scattering (LAS) technique was employed to quantitatively and simultaneously measure the concentration distributions of both the liquid and vapor phases in the fuel spray injected by the common rail hole-type injector for D.I. diesel engines. Based on the LAS measurements of the temporal variations of the concentration distributions in the fuel spray, the effects of injection pressure and nozzle hole diameter were examined. The detailed mixture properties, such as mass of vapor/liquid phases and entrained ambient air, mean equivalence ratio under various injection conditions, were obtained. The comparisons on axial fuel concentration between the momentum theory and the LAS measurement were also made. The results show that increasing the injection pressure can enhance the ambient air entrainment, correspondingly promote the fuel-air mixing and eventually improve the fuel evaporation, whereas the effect of nozzle hole diameter on the fuel-air mixing and evaporation presents double-faced.