Numerical study of hot-gas ventilated supercavitating flow

Abstract

This paper describes a numerical investigation of the characteristics of supercavitating flow using hot gas. The numerical results are validated through an experimental study under the same conditions at Chungnam National University Cavitation Tunnel. The temperature gradient, velocity profile, and pressure distribution inside the supercavity are investigated. The multiphase numerical study uses the volume of fluid method and the realizable k–ε turbulence model to solve the governing equations. The internal flow structure inside the hot-gas ventilated supercavity can be classified into three distinct regions: the hot-gas ventilation effect region, internal boundary layer, and reverse flow region. The pressure inside the supercavity remains unchanged in the region close to the cavitator, and does not depend on the temperature variation of the ventilation gas; however, a slight increase in pressure occurs in the region near the closure part of the supercavity with maximum increase of 18%. Moreover, the gas leakage mechanism of the hot-gas ventilated supercavity is found to be the twin-vortex tubes, which become a single-vortex tube as the free-stream velocity increases. The temperature distribution is concentrated in the hot-gas effect region. The hot-gas is observed to diffuse very quickly near the injection holes. The present article provides a better understanding of the fluid mechanism inside supercavities, and presents new results on the behavior of hot-gas ventilation. • Simulation of hot-gas ventilated supercavity (the highest temperature of 2773 K) is carried out. • The results reveal findings below. (1) Internal flow structure of the supercavity. (2) Pressure and temperature distributions inside the supercavity. (3) Hot-gas leakage mechanism through the twin-vortex tubes.