Experimental study of the cavitation on bio-inspired hydrofoils with leading-edge protuberances

Abstract

Devices that suffer from cavitation can have their lifetime and efficiency decreased. A possible alternative found in the literature to mitigate the cavitation is the use of bio-inspired devices such as leading-edge protuberances. It was verified that the protuberances can increase the lift and reduce the cavitation in specific conditions. So, we investigated, in an experimental work, the possibility of mitigating the cavitation in hydrofoils with leading-edge protuberances. The models analysed are the baseline and two kinds of sinusoidal leading-edge geometries (protuberances) called 4S and 4M. The experimental methodology involved flow visualisation techniques in the vertical hydrodynamic tunnel. The flow was registered by a camera in a range of 2° to 14° of angle of attack and for a Reynolds number up to approximately 2 × 104. After recording the possible incipient cavitation, a high-speed camera was used in a deeper investigation of the best conditions. It was observed a tendency for bubbles to appear in lower Reynolds numbers with the increase of the angle. At an angle of 8°, a significant mitigation of bubbles in the 4S foil is noticeable compared to the other models under the same conditions. Additionally, it was obtained, with the high-speed camera, a detailed visualisation of the incipient cavitation on these bio-inspired hydrofoils that allowed to record more precisely the occurrence of coalescence and the origin of the adhered bubbles. The results obtained can be used as a benchmark in numerical simulation research.