Numerical study on the effect of the cavitation phenomenon on the characteristics of fuel spray

Abstract

In direct injection diesel engines, the shape of spray and quality of atomization strongly affect the performance and outlet emissions of engine. If this spray leads to smaller droplets, combustion will become better and faster, performance and torque will be increased, and outlet emissions will be decreased. Cavitation phenomenon in the injector hole of the combustion engines has significant effect on the fuel spray characteristics. In this work, for certain geometry of nozzle, effects of cavitation on quality and spray characteristics like penetration length, SMD and distribution of fuel, was studied numerically. The commercial code, FIRE was used for meshing and simulating and solving the conservation equations, which are based on finite volume method. Finite difference schemes were selected for discretisation of momentum equation and upwind scheme was selected for turbulence and energy equations and the k-ε model was used for simulating the turbulence. The DDM method was selected for modeling the spray flow and finally the WAVE model was selected to study the droplets breakup and secondary break up. To create cavitation phenomenon and study its effects on the spray characteristics, different values of R/D were selected and for all different values of R/D, spray characteristics are obtained and consequently the effect of cavitation phenomenon on the spray quality was revealed.