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Article

Scattering and Directionality Effects of Noise Generation from Flapping Thrusters Used for Propulsion of Small Ocean Vehicles

1
School of Naval Architecture & Marine Engineering, National Technical University of Athens (NTUA), Heroon Polytechniou 9, 15780 Athens, Greece
2
School of Mechanical Engineering, National Technical University of Athens (NTUA), Heroon Polytechniou 9, 15780 Athens, Greece
*
Author to whom correspondence should be addressed.
Academic Editor: Michele Viviani
J. Mar. Sci. Eng. 2022, 10(8), 1129; https://doi.org/10.3390/jmse10081129
Received: 24 July 2022 / Revised: 6 August 2022 / Accepted: 11 August 2022 / Published: 17 August 2022
Flapping-foil thrusters are systems that operate at a substantially lower frequency compared with marine propellers and are characterized by a much smaller power concentration. These biomimetic devices are able to operate very efficiently, offering desirable levels of thrust required for the propulsion of small vessels or autonomous underwater vehicles (AUVs), and can be used for the standalone propulsion of small vessels or for augmenting ship propulsion in waves, alleviating the generation of noise and its adverse effects on sea life, particularly on marine mammals. In this work, we consider the generation of noise by flapping foils arranged in the neighborhood of the above vessels including the scattering effects by the hull, which, in addition to free-surface and seabed effects, significantly contribute to the modification of the characteristics of the acoustic field. A Boundary Element Method (BEM) is developed to treat the 3D scattering problem in the frequency domain forced by monopole and dipole source terms associated with the Ffowcs Williams and Hawkings (FW-H) equation. Numerical results are presented in selected cases illustrating that the hull geometry and acoustic properties, as well as the sea surface and seabed effects, are important for the determination of the directionality of the generated noise and significantly affect the propagation in the underwater ocean environment. View Full-Text
Keywords: flapping thruster; AUV; noise generation and propagation; scattering and directionality effects flapping thruster; AUV; noise generation and propagation; scattering and directionality effects
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MDPI and ACS Style

Belibassakis, K.; Prospathopoulos, J.; Malefaki, I. Scattering and Directionality Effects of Noise Generation from Flapping Thrusters Used for Propulsion of Small Ocean Vehicles. J. Mar. Sci. Eng. 2022, 10, 1129. https://doi.org/10.3390/jmse10081129

AMA Style

Belibassakis K, Prospathopoulos J, Malefaki I. Scattering and Directionality Effects of Noise Generation from Flapping Thrusters Used for Propulsion of Small Ocean Vehicles. Journal of Marine Science and Engineering. 2022; 10(8):1129. https://doi.org/10.3390/jmse10081129

Chicago/Turabian Style

Belibassakis, Kostas, John Prospathopoulos, and Iro Malefaki. 2022. "Scattering and Directionality Effects of Noise Generation from Flapping Thrusters Used for Propulsion of Small Ocean Vehicles" Journal of Marine Science and Engineering 10, no. 8: 1129. https://doi.org/10.3390/jmse10081129

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