Numerical investigation of body and hole effects on the cavitating flow behind a disk cavitator at extremely low Cheek for cavitation numbers

Supercavitation has been recently proposed as an effective method for drag reduction of underwater vehicles. For this purpose, a cavitator is used to generate a large continuous bubble to cover the vehicle. Extremely low cavitation numbers are required in these applications to provide a sufficiently voluminous cavity. In this study, the effects of body presence inside the cavity of a disk-shaped cavitator are studied numerically. An element based finite volume approach is used for solving Reynolds-averaged Navier-Stokes equations. In order to validate the numerical scheme, turbulence and cavitation models, the cavitating flow over a hemispherical nosed cylinder body and also behind a disk-shaped cavitator has been simulated and the numerical results are validated against existing analytical and experimental data. Next, the effects of body presence inside the cavity of the disk-cavitator on the cavity characteristics are investigated. Results show that the cavity length is slightly smaller when it closes on the body, in comparison with the freely-closing cavity. Furthermore, the effects of adding a concentric hole with various diameters to the disk-cavitator on the cavity features are examined. The degree of drag reduction and changes of the cavity dimensions are determined at various cavitation numbers. (C) 2018 Elsevier Inc. All rights reserved.