Numerical study of cavitating flow in orifices and its effect on spray characteristics

Abstract

The bubbly flow regime inside orifices has significant effects on several applications, and studying its trend along an orifice could be helpful in identifying the flow mechanism in various situations. The flow regime inside an orifice depends on the situation which has been specified for the orifice. Orifice geometry has a considerable effect on bubbly flow in injectors. Meanwhile, spray characteristics are influenced by the fuel flow inside an orifice, which has strong effects on the mixture of fuel - air. In this study, spray characteristics are studied for different values of the orifice angle. The cavitation phenomenon which occurs inside an orifice varies in intensity and patterns at different angles of the orifice and consequently has diverse effects on spray characteristics. The governing equations are solved by the SIMPLE algorithm. The spray flow is modeled by the discrete droplet method (DDM), the droplet breakup is modeled by the WAVE model, and the primary breakup is modeled by the DIESEL BREAK UP model. In order to generate cavitation phenomenon inside orifices and investigate its effect on spray characteristics, the angle of orifice with respect to the injector body is varied and the problem is studied for different angles of orifice.