Experimental and numerical investigation on the gas leakage regime for ventilated tail cavity of an underwater vehicle

The objective of this paper is mainly to investigate the ventilated tail cavity flow of an underwater vehicle with focus on the gas leakage regime by experimental and numerical methods. A high-speed camera and pressure measurement system are used to record the cavity flow patterns and pressure behavior, respectively. The numerical simulation is carried out with volume of fluid (VOF) model and Filter-based turbulence model (FBM). Good agreement can be obtained between the experimental and numerical results. There are three gas leakage types in the evolution of the intact tail cavity, i.e., twin-vortex tube entrainment (TVTE), toroidal vortex shedding (TVS) and hybrid twin-vortex tube entrainment and toroidal vortex shedding (TVTE-TVS). With the increase of Fr, the unsteady behavior of the cavity with different gas leakage types becomes more apparent. The internal flow characteristics revealed three distinct regions including the ventilation influence region, the reverse flow region and the high shear flow region and have an important effect on the transition of gas leakage regime.