Experimental and numerical study on flow dynamics and universal characteristics of ventilated supercavities behind different cavitators

Abstract

In this study, physical aspects of a ventilated supercavity behind different cavitator geometries such as the hydrodynamic characteristics, distribution of pressure within the cavity, hysteresis phenomenon, and gas leakage mechanism were qualitatively and quantitatively investigated using experimental and numerical methods. For the simulation and tunnel tests, we employed five cavitators, each with different angles (45°, 60°, 90°, 135°, and a 180° cavitator, commonly referred to as a disk cavitator), all sharing the same diameter. The results revealed that the drag force experienced on the cavitator decreased linearly with an increase in the ventilation rate, and a consistent trend was observed for all test cavitator angles. Through experimental measurements, a universal equation has been derived to predict the drag force exerted on a supercavitating vehicle employing a cavitator. In addition, the pressure distribution inside the supercavity was significantly influenced by the angle of the cavitator. The pressure kept almost unchanged in the first half of supercavity; a slight increase in pressure occurred in the remainder of the supercavity. Twin-vortex gas leakage mode was clearly observed. The distance between the two hollow vortices increased significantly, whereas the incline angle of these vortices and the horizontal line changed insignificantly.