Droplet Size Distribution in Diesel Fuel Spray

Measurments on the behavior of diesel fuel spray from a microscopic viewpoint are important to clarify atomization mechanism and temporal change in droplet size distribution. In this study, diesel spray injected from diesel nozzles into a quiescent atmosphere at room temperature and high pressure is observed by means of a direct microscopical photographing method varying the photographing time and the nozzle type. The results show that the mechanism of spray atomization is divided into 4 processes, and spatial distributions of breakup droplets are assessed. As time passes, spray droplets are distributed in a stratiform shape. And total distribution of droplet sizes and droplet size distribution in local region are expressed in equations as a function of time from injection, and changes in the distribution with the nozzle type are discussed. Subsequently, temporal changes in the uniformity of the distribution and in spatial distribution of droplets volume rates are clarified.