Effects of Cavitation Control Methods on Structural Vibration

This thesis investigates passive cavitation control methods and their impact on the fluid-structu-re interaction (FSI) of hydrofoils in cavitating flows, with a particular focus on cavitation-induced vibrations, hydroelastic responses, and cavitation suppression strategies. First, the effectiveness of bio-inspired riblets in reducing cavitation volume and hydrodynamic forces was examined using a circular cylinder. Next, the influence of passive cavitation control on a hydrofoil was explored, with a focus on both cavitation mitigation and acoustic reduction. Additionally, cavitating flow around both rigid and flexible hydrofoils was analyzed across different cavitation regimes in the absence of control measures. To address these effects, a passive cavitation control strategy utilizing biomechanical riblets was developed and applied in various riblets configurations. Advanced experimental techniques, including high-speed imaging, digital image correlation (DIC), acoustic signal detection, and hydrodynamic force measurements were employed within this study. Results demonstrated a substantial reduction in cavitation volume and sound pressure levels through passive control. Specifically, the application of bio-inspired riblets effectively suppressed large-scale cloud cavitation and weakened re-entrant jet formation, thereby mitigating the structural response of flexible hydrofoils. Additionally, a spanwise wedge structure at the leading edge was explored as a passive control mechanism, further reducing cavitation-induced vibrations. The experimental findings offer new insights into the coupled dynamics of FSI in cavitating flows and validate the effectiveness of passive control methods in enhancing hydrofoil performance. These results contribute to the advancement of marine engineering design, particularly in mitigating cavitation-induced damage and improving hydrodynamic efficiency.