Study of characteristics of unsteady cavitating flow around an axisymmetric blunt body

Cavitating flow around an axisymmetric blunt body is studied based on the experiments and numerical simulations. A high-speed video camera is used to observe the processes of cavity development and shedding. A partially-averaged Navier-Stokes (PANS) method which is a hybrid RANS/LES turbulent model is applied in numerical simulation. The results show that the characteristics of cavity developing and shedding vary as cavitation number is changied. With the decrease in the cavitation number, the period of cavity developing increases and the shedding of small scale vortices occurs. Moreover, it is found that the shedding generally contains two processes: cavity break-off and cavity shedding. The cavity break-off probably occurs at the location which is about 0.3D away from the shoulder. The cavity sheds with U-vortex type which is induced by the re-entrant flow. In addition, the cavity tends to be steady when the break-off cavity is in conjunction with the attached cavity.