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.

Tip vortex cavitation (TVC) leads to several technical problems, such as efficiency loss and noise. This study explains the patterns of flow around the tip of an elliptical foil and the cavity shape deformations under different flow conditions through experimental analysis. There is good agreement between the vortex cavity shapes captured by this high-speed imaging and those derived in previous studies. Using laser Doppler velocimetry (LDV) measurements and analysis through image processing of high-speed images, we compare the vortex core trajectories in cavitating and non-cavitating conditions.

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. 

The influence of sweep angles on cavitation characteristics and mechanisms of a wedge-section hydrofoil is investigated experimentally and numerically. The wake vortex changes from eddy vortex shedding at the wake region of the straight hydrofoil into two root trailing-edge vortices as the sweep angle increases. The swept hydrofoil reduces the average cavity volume by more than 45% compared with the straight foil. The findings offer valuable insight into the design and optimization of foils for various applications where cavitation affects their performance and stability.