CAVITATION IN INJECTOR NOZZLE HOLES - A PARAMETRIC STUDY

The fuel injection system in diesel engines has a consequential effect on the fuel consumption, combustion process and formation of emissions. Cavitation and turbulence inside a diesel injector play a critical role in primary spray breakup and development processes. Thus understanding the phenomenon of cavitation is significant in capturing the injection process with accuracy. In this study, the cavitating flow inside an injector nozzle hole was numerically investigated. The two-phase mixture model by Schnerr and Sauer (2001) was adopted along with k-epsilon turbulence model and Fluent CFD package was used to solve the governing equations numerically. The validation of the model was done by comparing the numerical results with the experimental results of Winklhofer et al. (2001) for U-throttle geometry and a good agreement was found. In this paper, a detailed parametric study on the effects of injection pressure, transient analysis for diesel and SME (Soy Methyl Esther) bio-diesel and different geometries on cavitation phenomenon inside the injector nozzle hole was done. The results show that the bio-diesel inhibits the cavitation phenomenon compared to diesel fuel, and positive Kfactor nozzles have higher mass flow rate and higher exit velocity.