Unsteady behavior of ventilated cavitating flows around an axisymmetric body

The objective of this paper is mainly to investigate the ventilated cavitating flow characteristics around an axisymmetric body with a focus on three-dimensional unsteady behaviors. A high-speed camera technique is used to record the ventilated cavitating flow patterns. A homogeneous free surface model coupled with Filter-based turbulence model is used to simulate the time-evolution process of the unsteady cavitating flows. Numerical results show a reasonable agreement with the experimental data. The evolution of the ventilated cavity quasi-periodic unsteady shedding is well captured and discussed. The asymmetric and three-dimensional unsteady behaviors are impressive in the ventilated cavitating flow. Further analysis demonstrates that the re-entrant jet which originates from different circumferential positions at the closure region of the cavity moves upstream with different speeds. Lagrangian coherent structures (LCS) methods are applied to reveal the influence of re-entrant jet on the U-type cavity shedding and it shows that there is a close relationship between unsteady behaviors and the re-entrant jet flow motion consisting of moving upstream and circumferential. In addition, the effect of asymmetry on unsteady shedding behaviors of ventilated cavitating flow at different angles of attack have also been investigated combined with LCS methods.