Numerical investigation of the cavitation phenomenon on spray behavior of diesel fuel in injector

In direct injection diesel engines, diesel nozzle geometry is a major issue in order to fulfill control of emission due to the influence on internal flow, cavitation phenomenon, spray characteristics and therefore atomization behavior, which are very important for engines performance and
pollutant formation. The aim of this article is to study the effect of cavitation on Diesel spray behavior such as spray penetration lengths and sauter mean diameter. In this study To create a cavitation phenomenon and to investigate its effect on the fuel spray characteristics two similar injector different in the inlet cross section nozzle have been considered and their internal liquid flow and the behavior of their resulted sprays have been investigated( this has been done by moving nozzle on the injector body). AVL-Fire CFD code has been used for meshing and simulating and solving the conservation equations. The results show that by placing the nozzle hole in lower part of the injector sac, the volume fraction of the vapor phase increases. So the growth of the cavitation phenomenon increases. Also the results of the spray show that the spray penetration length for lower nozzle hole increases. An interesting point is that there is no significant change in the size of the spray droplet for two injectors. Most importantly, the spray penetration length can be controlled by place of nozzle hole.