Flow noise response of a diaphragm based fibre laser hydrophone array

Chandrika, Unnikrishnan Kuttan; Pallayil, Venugopalan; Lim, Kian Meng; Chew, C. H.

doi:10.1016/j.oceaneng.2014.09.014

Cited by 5 publications

(2 citation statements)

References 27 publications

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“…Especially at medium and high velocity, hydrodynamic noise has become the main factor to affect the self-noise of sonar platforms on underwater vehicles. The study and suppression of the hydrodynamic noise on the surface of the underwater vehicle dome and towing array [11][12][13][14][15][16] attach great importance to increase the detection range of the sonar platform and improve the signal-to-noise ratio. Traditionally, the acoustic performance of underwater vehicles is considered from linear optimization, material optimization, and structural optimization.…”

Section: Introduction and Principle Headingsmentioning

confidence: 99%

Noise Reduction Effect of Superhydrophobic Surfaces with Streamwise Strip of Channel Flow

et al. 2021

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Superhydrophobic surface is a promising technology, but the effect of superhydrophobic surface on flow noise is still unclear. Therefore, we used alternating free-slip and no-slip boundary conditions to study the flow noise of superhydrophobic channel flows with streamwise strips. The numerical calculations of the flow and the sound field have been carried out by the methods of large eddy simulation (LES) and Lighthill analogy, respectively. Under a constant pressure gradient (CPG) condition, the average Reynolds number and the friction Reynolds number are approximately set to 4200 and 180, respectively. The influence on noise of different gas fractions (GF) and strip number in a spanwise period on channel flow have been studied. Our results show that the superhydrophobic surface has noise reduction effect in some cases. Under CPG conditions, the increase in GF increases the bulk velocity and weakens the noise reduction effect. Otherwise, the increase in strip number enhances the lateral energy exchange of the superhydrophobic surface, and results in more transverse vortices and attenuates the noise reduction effect. In our results, the best noise reduction effect is obtained as 10.7 dB under the scenario of the strip number is 4 and GF is 0.5. The best drag reduction effect is 32%, and the result is obtained under the scenario of GF is 0.8 and strip number is 1. In summary, the choice of GF and the number of strips is comprehensively considered to guarantee the performance of drag reduction and noise reduction in this work.

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Section: Introduction and Principle Headingsmentioning

confidence: 99%

Noise Reduction Effect of Superhydrophobic Surfaces with Streamwise Strip of Channel Flow

et al. 2021

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“…[15][16][17] Since the towing experiments were conducted in open water (lakes/seas), the TBL parameters such as d/a could not be measured unlike in wind or water tunnel. 10,[18][19][20] These papers offer baseline experimental data to validate CFD models for wall pressure spectra (Table 1).…”

Section: Introductionmentioning

confidence: 99%

Numerical prediction of flow noise levels on towed sonar array

Karthik

Jeyakumar

Sebastin

2020

Proceedings of the Institution of Mechanical Engineers, Part M:

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Flow noise originating in the turbulent boundary layer (TBL) often severely limits the performance of towed sonar array. Therefore, it is necessary to predict this noise for the design of an efficient towed array. This paper presents large eddy simulation methodology to establish the TBL properties and wall pressure fluctuations on a 12 m long towed array with length to diameter ratio of 1200 in the operating tow speed range of 2 to 5 knots in water. The computed flow noise levels are compared with experimental measurements available in the literature successfully. The effectiveness of scaling the flow noise spectra with the diameter and tow speed is discussed, and non-dimensional wall pressure spectra presented with respect to non-dimensional frequency. The overall sound pressure levels are also compared with experimental data that show good accuracy achieved by the proposed numerical methodology.

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