CFD investigation of fuel property effect on cavita ting flow in generic nozzle geometries

Abstract

This paper reports a numerical study of the effect of fuel property and fuel temperature change on mec hanical cavitating flow in generic nozzle geometries. The w ork was based on the commercial CFD code ANSYS CFX11.0. The liquid and the vapor phase were treate d as a homogeneous mixture with a transport equatio n for the volume fraction of the vapor phase. The cavitat ion induced inter-phase mass transfer was calculate d by a Rayleigh-Plesset-Equation based cavitation model. F irst, model parameter calibration was carried out a nd the results were validated against experimental results . Then, investigations were carried out for the eff ects of three important properties, namely the fuel vapour satura tion pressure, density and viscosity, on cavitation behaviour. Simulations were carried out by varying each of the parameters and keeping the other constant in the s ame time and by varying the temperature for the fuel n-hepta ne. Their influences on the discharge coefficient, critical cavitation point, vapour volume fraction distribution, and flow velocity development in the nozzle throttl e were evaluated. The results indicate a strong influence of Reynolds number on mechanical cavitation phenomenon. In addition, the results were found to be useful for u nderstanding and interpretation of practical spray visualization and engine experiment results.