Numerical prediction of periodic cavitation shedding in cylindrical orifice

Cavitation structures inside orifice of high pressure fuel injector nozzles have a major influence on internal flow and quality of spray. The present work provides a detailed understanding of the effect of injection pressure on cavitation and its shedding in the form of cloud cavities inside a cylindrical orifice. Commercial computational fluid dynamics (CFD) software, ANSYS Fluent with Reboud’s correction on the eddy viscosity term of k-ω SST turbulence model is used for the numerical investigations. Comparison of the results with literature on experimental studies shows that the employed modification of turbulent viscosity term by a user defined function helps in prediction of reentrant jet induced cavity shedding. Compressible, multi-phase simulations revealed non-cavitating, periodic cloud shedding, super cavitating and hydraulic flip regimes. Fourier transformation is performed on the time series data of fluctuating vapor fraction to predict the frequency of shedding of cavities for various cavitation numbers. It is shown that with a reduction in cavitation number, length of cavity increases and shedding frequency decreases.