Shedding frequency of sheet cavitation around axisymmetric body at small angles of attack

Abstract

Cavity shedding of cavitating flows around an axisymmetric body belongs to the unsteady cavitating flows in the condition of steady incoming current. The periodic characteristics of unsteady cavitating flows around an axisymmetric body at small angles of attack are investigated experimentally and numerically. The evolution and shedding process of the three-dimensional sheet cavitation are computed numerically by the Reynolds averaged Navier-Stokes equations and the RNG k − ɛ model. The modification approach for eddy viscosity coefficient in the transition area of the two-phase flow is adopted to reproduce the shedding process of cavitating flows. The computed frequency of the cavity shedding coincides with the experimental data for the cases of unsteady cavitating flows around axisymmetric bodies with four headforms. Given the cavitation number, the shedding process of the cavitating flow depends heavily on the headform of the axisymmetric body. If the angle of attack of the axisymmetric body is greater than a critical value, the violent shedding of the sheet cavitation seems to be depressed.