Experimental and numerical analysis of the physical characteristics of natural and ventilated supercavitating flows

In this experimental and numerical study, we investigate the physical characteristics of a supercavitating flow generated behind a disk-shaped cavitator under both natural and ventilated conditions, an area of research that has not been thoroughly examined. Initially, the experiment is conducted within a cavitation tunnel employing a forward-facing model, complemented by high-speed visualization techniques. Subsequently, an unsteady Reynolds-averaged Navier-Stokes approach is adopted to conduct numerical simulations along with the k-epsilon turbulent model and Ffowcs Williams-Hawkings (FW-H) methods. The outcomes of the study demonstrate that when considering fixed cavitation numbers, the profiles of natural and ventilated cavities are consistent. Under constant flow conditions, the introduction of ventilating air leads to a discernible reduction in hydroacoustic characteristics in the high-frequency spectrum and has the potential to improve flow stability behind the cavitator. The numerical results offer insight into the behaviors of the water, vapor, and ventilation air. In the foamy cavity stage, all the considered phases (water, vapor, and ventilation air) coexist inside the cavity. Upon the formation of a transparent supercavity, the ventilation air primarily gathers around the ventilation holes and the surrounding gas-leakage region. Meanwhile, the vaporous gas is dominant and is concentrated predominantly in the central region of the supercavity. The findings extracted from this study represent a significant advancement in our understanding of the intricacies of supercavities under ventilated and vaporous conditions. These insights hold the potential to drive groundbreaking innovations in the design and control of supercavitating vehicles.