Research on collapse characteristics of ventilated cavities around an underwater vehicle

The collapse characteristics of ventilated cavities around an underwater vehicle are studied through water tunnel experiment, and a behavior of a ventilated cavity stopping subsequent cavity from generating is analiyzed. In order to analyze the oscillation characteristics of cavities during collapse, the high-speed camera and dynamic force-measuring systems are used to record the evolution process of ventilated cavities and the change in pressure on underwater vehicle. The experimental results show that the changing process of shed cavity can be classified into four periods: generation, cavity breakage, cavity shedding, and collapse. Cavity collapse depends on the state of flow field. The cavity collapses when the flow is in turbulent state. The cavity collapse at a fixed point can be captured by the pressure sensors. As a shed cavity moves near mode boundary, the cavity collapses. The shed cavity and pressure are investigated experimentally, and the experimental results of collapse pressure are compared with the calculated results based on Rayleigh-Plesset equation. The experimental value of collapse are in good agreement with the theoretical value.