supercavitation

LES simulation predicts variations in supercavity geometry, hydrodynamic force, and supercavitating internal flow under the influence of the forebody length. The results indicate that the time required to generate a clear supercavity for the model with a 10dc forebody length is 6% and 9% less than for the 15dc and 20dc forebody length models, respectively. Additionally, the 10dc forebody length model experiences about 5% smaller total drag force than the longer models. The variations in forebody length significantly influence the supercavitating internal flow and pressure distribution inside the supercavity. Specifically, the ventilation air is distributed as an outer layer of the supercavity for the 10dc forebody length model. 

Air injection in water has several engineering advantages, such as an air lubrication system, cavitation control, and noise reduction. This study investigates the effect of air injection rate and stream velocity on bubble layer volume fraction, thickness, and noise mitigation. Higher stream velocity promotes air bubble breaking and the formation of diverse air bubble patterns such as mono-dispersion bubbles and clustering bubbles. The insertion loss increases with stream velocity as higher flow velocity leads air bubbles to break and form bubble clusters, which is found to be more effective in reducing noise than a single bubble.

Despite decades of rigorous research into supercavitating flow, there is still a lack of in-depth knowledge on ventilated supercavitation with cavitators of varying angle of attack. To address this gap, this study aimed to investigate numerically the supercavity profile, internal pressure behavior, and gas leakage mechanism taking into account the effects of cavitator angle of attack. The results show that changes in the cavitator’s angle of attack have considerable effects on the length and deformation of the supercavity profile. 

Experimental investigation on drag characteristics and flow physics of ventilated supercavitating objects with different body shapes was conducted. The test model consists of a disk-type cavitator with two different fore bodies (slender and blunt shape) and three different rear bodies (flat, shrinkage, and expanded shape). The drag forces acting on different body combinations in fully wetted conditions are measured and the results show that the drag coefficients strongly depend on the body shapes. It explains in detail through particle image velocimetry measurements. The drag characteristics are systematically examined over a broad range of ventilation rates.