Whale-inspired hydrofoil design reduces cavitation, noise

One of the biggest problems faced by designers of underwater propellers and turbines is cavitation. At the surface of moving edges, large pressure drops can result in a sudden vaporization of the fluid, which leads to a loss of efficiency and structural damage. Cavitation is also a leading cause of underwater noise pollution, which hurts wildlife and damages ecosystems.

Simanto et al. tested an alternative hydrofoil design inspired by humpback whale fins. By adding protuberances to the leading edge of the hydrofoil, they sought to minimize cavitation effects and uncover how the design affects fluid flow. In particular, they sought to understand the development of sheet cavities and the shedding of cloud cavities, two forms of partial cavitation common in hydrofoils.

“In our experiment, we modified the leading edge of the hydrofoil models with sinusoidal protuberances,” said author Byoung-Kwon Ahn. “According to our observations, leading-edge protuberances can effectively suppress both cavitation and noise at higher Reynolds numbers when the partial sheet cavity grows large and cloud shedding is more significant as a noise source.”

Previous studies have found that leading-edge protuberances improve hydrofoil efficiency, and the authors sought to test the impact on cavitation. Using a cavitation tunnel, they subjected a collection of hydrofoils with different protuberance shapes to a variety of conditions and analyzed the results. They found that the protuberances direct the flow into the troughs, limiting the amount of cavitation. Under certain conditions, cavitation can be reduced by up to 60 percent.

“We are now working on designing three dimensional models with leading-edge protuberances, and we will conduct experiments and numerical analysis,” said Ahn.

Source: “Experimental investigation on cavitation and induced noise of two-dimensional hydrofoils with leading-edge protuberances,” by Rafat I. A. Simanto, Ji-Woo Hong, Ki-Seong Kim, Byoung-Kwon Ahn, and Suyong Shin, Physics of Fluids (2022). The article can be accessed at https://doi.org/10.1063/5.0127170 .

This paper is part of the Cavitation Collection, learn more here .