Optimization of a novel biomimetic vortex generator structure based on cavitation intensity and stability control

Abstract

Cavitation phenomena in the fields of hydraulic machinery and underwater submersibles have brought numerous negative impacts, such as vibration noise and mechanical damage. To suppress cavitation intensity and reduce the negative effects of cavitation instability, a biomimetic vortex generator (BVG), arranged on the surface of hydrofoils, is proposed in this study. The renormalization group k-ε turbulence model with density correction and the Ffowcs Williams and Hawkings acoustic model are employed. The cavitation intensity and cavitation stability of the BVG hydrofoil at different arrangement densities are analyzed. Cavitation control performance can be enhanced by reducing the spacing between structures on the hydrofoil. However, an excessively high BVG arrangement density may cause large-scale cavities to collapse prematurely, promoting the formation of small-scale cavities. This exacerbates cavitation instability, intensifies high-frequency pressure oscillations, and consequently amplifies noise. To mitigate performance degradation in hydrofoils caused by high-density BVG arrangements, the effects of structural height on the reentrant jet and surface vortices are analyzed. As a result of BVG structural optimization, cavitation intensity is further reduced, and cavitation stability is improved. Compared to the baseline hydrofoil, the time-averaged vapor volume over three cavitation cycles is reduced by 22.68%, the overall sound pressure level at receiver F decreases by 5.7 dB, and the dominant frequency of S3h2 hydrofoil cavitation decreases by 1.87 Hz. Ultimately, the optimization of the BVG structure enhances cavitation stability and significantly reduces high-frequency noise caused by pressure fluctuations on the hydrofoil surface.