Control effect of superhydrophobic grooves on flow-induced noise generated by flow around cylindrical shell at large Reynolds number

Flow-induced noise is an important factor affecting the quiet performance of underwater vehicles. Superhydrophobic surfaces are an emerging technology for underwater vehicles. In this study, a superhydrophobic surface is innovatively applied to the flow-induced noise control of underwater cylindrical shells. Alternating no-slip and no-shear surfaces are used to simulate the superhydrophobic surface with spanwise superhydrophobic grooves so that the flow regime and flow-induced noise of a no-slip cylinder are compared with the superhydrophobic cylinder under a high Reynolds number. The results show that the superhydrophobic surface can effectively delay flow separation and control the size of the wake shedding vortex. The flow-shedding vortices mainly affect the flow-induced noise in the lower frequency range, which is consistent with the vortex shedding frequency. The radiation characteristics of the flow-induced noise generated by the fluctuation pressure are mainly influenced by the eigenfrequency of the model in the range of 100 Hz-5000 Hz. Moreover, the superhydrophobic surface can effectively reduce the flow-induced noise and change its radiation directivity at both high and low frequencies by controlling vortex shedding and reducing the fluctuation pressure, respectively. The findings reported here shed new light on the flow-induced noise control of underwater vehicles.