A study on the Lloyd’s mirror effect on the underwater radiated noise for the underwater vehicle

Seung-Hee Kang

doi:10.7776/ASK.2021.40.4.314

All Issue

2021 Vol.40, Issue 4 Preview Page Next Page

Research Article

A study on the Lloyd’s mirror effect on the underwater radiated noise for the underwater vehicle 수중운동체 방사소음의 로이드 미러 효과 연구

31 July 2021. pp. 314-319

PDF XML

Abstract

The measurement of the Underwater Radiated Noise (URN) for the underwater vehicle should consider both the acoustic interference due to the surface reflection and the calculation of the Closet Point of Approach (CPA). In this paper, I tried to analyze the underwater vehicle’s URN using the Lloyd’s mirror effect. First, the theoretical Lloyd’s mirror pattern was compared with the sea trial result, and the sea trial results corresponded well with the theoretical predicted pattern. And then the CPA distance could be estimated by the Lloyd’s mirror pattern. As a results, acoustic source level shows the spectral fluctuation due to the acoustic interference of the Lloyd‘s mirror effect.

Keywords

Underwater Radiated Noise (URN)

Spectrum level

Lloyd’s mirror effect

Interference pattern

수중운동체의 수중방사소음을 측정하기 위해서는 수중음향 최근접점 거리의 계산과 해표면 반사 등에 의한 음향간섭이 음향준위에 미치는 영향이 고려되어야 한다. 그러므로 본 논문에서는 해표면 반사에 의한 음향간섭으로 발생하는 로이드 미러 효과가 수중운동체의 수중방사소음 측정 결과에 미치는 영향을 분석하고자 하였다. 수중운동체의 수중방사소음 측정결과에 로이드 미러 효과에 의한 주파수스펙트럼 레벨의 변동이 나타나는 것을 확인하였고, 이론식으로부터 예측한 로이드 미러 패턴이 측정결과와 일치됨을 확인할 수 있었다. 확인된 로이드 미러 패턴으로부터 수중운동체의 최근접점거리를 추정하였으며, 표면 간섭으로 나타나는 로이드 미러 효과가 수중운동체의 수중방사소음 준위 분석에 영향을 미치는 것을 확인하였다.

키워드

수중방사소음

스펙트럼 레벨

로이드 미러 효과

간섭무늬

References

ANSI/ASA S12.64-2009/Part 1, Quantities and Procedures for Description and Measurement of Underwater Sound from Ships, - Part 1 : general requirements, 2009.

G. Grelowska, E. Kozaczka, S. Kozaczka, and W. Szymczak, "Underwater noise generated by a small ship in the shallow sea," Archives of Acoustics, 38, 351-356 (2013). 10.2478/aoa-2013-0041

P. T. Arveson and D. J. Vendittis, "Radiated noise characteristics of a modern cargo ship," J. Acoust. Soc. Am. 107, 118-129 (2000). 10.1121/1.428344

A. Brooker and V. Humphrey, "Measurement of radiated underwater noise from a small research vessel in shallow water," Ocean Engineering, 120, 182-189 (2016). 10.1016/j.oceaneng.2015.09.048

M. A. Ainslie, Principles of Sonar Performance Modelling (Springer-Praxis, Chichester, 2010), pp. 34-36.

D. Ross, Mechanics of Underwater Noise (Peninsula Publishing, California, 1987), Chap. 2.5.

L. E. Kinsler, A. R. Frey, A. B. Coppens, and J. V. Sanders, Fundamentals of Acoustics (John Wiley & Sons, New Jersey, 1999), Chap. 15.

C. Audoly and V. Meyer, "Measurement of radiated noise from surface ships - Influence of the sea surface reflection coefficient on Lloyd's mirror effect," Proc. Mtgs. Acoust. Soc. Am. 1-10 (2017).

D. Kapolka, "Equivalence of the waveguide invariant and two path ray theory methods for range prediction based on Lloyd's mirror patterns," Proc. Mtgs. Acoust. Soc. Am. 3638-3641 (2008). 10.1121/1.2979233

Information

Publisher :The Acoustical Society of Korea
Publisher(Ko) :한국음향학회
Journal Title :The Journal of the Acoustical Society of Korea
Journal Title(Ko) :한국음향학회지
Volume : 40
No :4
Pages :314-319
Received Date : 2021-04-28
Revised Date : 2021-06-21
Accepted Date : 2021-06-30
DOI :https://doi.org/10.7776/ASK.2021.40.4.314

The Journal of the Acoustical Society of Korea ISSN:1225-4428(Print) 2287-3775(Online) 한국음향학회지

All Issue