Experimental study on dribbling characteristics of gasoline/biodiesel blends after the end-of-injection

Abstract

The effects of biodiesel addition on gasoline fuel dribbling process and characteristics after the end-of-injection (EOI) were investigated in a constant volume chamber at different injection pressures and ambient temperatures. The fuel dribbling process was recorded with high spatial and time resolution by using the microscopic shadow imaging technique, and the corresponding dribble velocity, dribble volume and droplet size were extracted. The results showed that the fuel dribbling experienced four typical morphological structures (spray-like, membrane-type, ligament-type, droplets) after the EOI under all the tested conditions. Additionally, increased biodiesel proportion in the blends caused decreased dribble velocity, longer dribbling duration, and increased droplet size, indicating deteriorated breakup and atomization processes of the dribbling flow. Moreover, the higher injection pressure increased the dribble amount but reduced the dribbling duration and droplet size. The increased ambient temperature caused faster evaporation of the dribbling fuel, resulting in a significant decrease in the dribble size. So, these two strategies were believed to be overall favorable to restrain the adverse effect on gasoline fuel dribbling characteristics caused by the addition of biodiesel.