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Reduction of Hydrodynamic Noise of 3D Hydrofoil with Spanwise Microgrooved Surfaces Inspired by Sharkskin

by Zhigao Dang 1,2,*, Zhaoyong Mao 1,2 and Wenlong Tian 1,2
1
School of Marine Science and Technology, Northwestern Polytechnical University, Xi’an 710072, China
2
Key Laboratory for Unmanned Underwater Vehicle, Northwestern Polytechnical University, Xi’an 710072, China
*
Author to whom correspondence should be addressed.
J. Mar. Sci. Eng. 2019, 7(5), 136; https://doi.org/10.3390/jmse7050136
Received: 4 April 2019 / Revised: 4 May 2019 / Accepted: 7 May 2019 / Published: 10 May 2019
(This article belongs to the Section Ocean Engineering)
Loud hydrodynamic noise is not only potentially harmful to the health of organisms in the ocean, but it is also a threat to the survival of underwater vehicles. Different from the general noise reduction technologies at present, a new idea for a flow-induced noise reduction design with spanwise microgrooved surfaces inspired by sharkskin is introduced in this paper. Large eddy simulations (LES) combined with the Ffowcs Williams and Hawkings (FW-H) equation are adopted to simulate the hydrodynamic noise of the three-dimensional (3D) hydrofoil. The accuracy of the numerical predictions is checked against existing experimental data, achieving good agreement. With the increase of observing distance, the noise reduction effect at the trailing edge direction is gradually apparent, and a maximum noise reduction of up to 7.28 dB can be observed. It is seen from the noise spectra of the biomimetic hydrofoil that the main peaks are eliminated, and the noise level at high frequency is also decreased. The cause of noise reduction lies in the secondary vortex generated in the microgrooves, which hinder the process of turbulence, consume the energy of the flow, and weaken the intensity of turbulent burst. The results of this study provide a new way to design low-noise underwater structures with hydrofoils. View Full-Text
Keywords: hydrodynamic noise reduction; spanwise microgrooved surface; large eddy simulation; hydrofoil; sound pressure; secondary vortex; biomimetic hydrodynamic noise reduction; spanwise microgrooved surface; large eddy simulation; hydrofoil; sound pressure; secondary vortex; biomimetic
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Dang, Z.; Mao, Z.; Tian, W. Reduction of Hydrodynamic Noise of 3D Hydrofoil with Spanwise Microgrooved Surfaces Inspired by Sharkskin. J. Mar. Sci. Eng. 2019, 7, 136.

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