Hydrodynamics and modeling of a ventilated supercavitating body in transition phase

Compared to other underwater vehicles, supercavitating vehicles can attain a high speed because they eliminate drag by creating a large cavity, thus establishing the so-called "supercavitating condition." Such a cavity is difficult to develop under normal conditions, hence, ventilation is used to attain the supercavitating condition in the initial phase of flight. In this paper, we focus on the hydrodynamic characteristics of a ventilated supercavitating vehicle. First, dynamic modeling of the supercavitating vehicle is performed to calculate the hydrodynamic force/moment acting on the vehicle for a given size of cavity. We then define the relationship between the ventilation rate and the cavitation number based on an air entrainment model of the ventilated cavity. Numerical simulations were performed to analyze the physical feasibility and characteristics of the modeling. The results show that the cavity length/radius increases with the ventilation rate, proving that ventilation can be used to attain the supercavitating condition.