Effect of nozzle transients and compressibility on the penetration of fuel sprays

Abstract

A study has been performed using a combination of high speed optical imaging and a synchrotron based technique to obtain a time history of nozzle exit velocity, discharge coefficient, and spray tip velocity of high pressure fuel sprays. The results support a recently proposed theoretical model of spray propagation that suggests a compressible region of flow immediately ahead of the spray has a strong influence on the evolution of the tip velocity profile. Coupled with this is the variation in discharge coefficient due to injector needle movement which largely governs the spray exit velocity immediately after start of injection.