Chin. Phys. B ›› 2013, Vol. 22 ›› Issue (12): 124301-124301.doi: 10.1088/1674-1056/22/12/124301

• ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS • 上一篇    下一篇

Investigation of long-range sound propagation in surface ducts

段睿, 杨坤德, 马远良   

  1. Institute of Acoustic Engineering, Northwestern Polytechnical University, Xi’an 710072, China
  • 收稿日期:2013-01-20 修回日期:2013-03-11 出版日期:2013-10-25 发布日期:2013-10-25
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No. 11174235), the Science and Technology Development Project of Shaanxi Province, China (Grant No. 2010KJXX-02), the Science and Technology Innovation Foundation of Northwestern Polytechnical University of China, and the Doctorate Foundation of Northwestern Polytechnical University, China (Grant No. CX201226).

Investigation of long-range sound propagation in surface ducts

Duan Rui (段睿), Yang Kun-De (杨坤德), Ma Yuan-Liang (马远良)   

  1. Institute of Acoustic Engineering, Northwestern Polytechnical University, Xi’an 710072, China
  • Received:2013-01-20 Revised:2013-03-11 Online:2013-10-25 Published:2013-10-25
  • Contact: Yang Kun-De E-mail:ykdzym@nwpu.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No. 11174235), the Science and Technology Development Project of Shaanxi Province, China (Grant No. 2010KJXX-02), the Science and Technology Innovation Foundation of Northwestern Polytechnical University of China, and the Doctorate Foundation of Northwestern Polytechnical University, China (Grant No. CX201226).

摘要: Understanding the effect of source-receiver geometry on sound propagation in surface ducts can improve the performance of near-surface sonar in deep water. The Lloyd-mirror and normal mode theories are used to analyze the features of surface-duct propagation in this paper. Firstly, according to the Lloyd-mirror theory, a shallow point source generates directional lobes, whose grazing angles are determined by the source depth and frequency. By assuming a part of the first lobe to be just trapped in the surface duct, a method to calculate the minimum cutoff frequency (MCF) is obtained. The presented method is source depth dependent and thus is helpful for determining the working depth for sonar. Secondly, it is found that under certain environments there exists a layer of low transmission loss (TL) in the surface duct, whose thickness is related to the source geometry and can be calculated by the Lloyd-mirror method. The receiver should be placed in this layer to minimize the TL. Finally, the arrival angle on a vertical linear array (VLA) in the surface duct is analyzed based on normal mode theory, which provides a priori knowledge of the beam direction of passive sonar.

关键词: surface duct, source-receiver geometry, Lloyd-mirror, normal mode

Abstract: Understanding the effect of source-receiver geometry on sound propagation in surface ducts can improve the performance of near-surface sonar in deep water. The Lloyd-mirror and normal mode theories are used to analyze the features of surface-duct propagation in this paper. Firstly, according to the Lloyd-mirror theory, a shallow point source generates directional lobes, whose grazing angles are determined by the source depth and frequency. By assuming a part of the first lobe to be just trapped in the surface duct, a method to calculate the minimum cutoff frequency (MCF) is obtained. The presented method is source depth dependent and thus is helpful for determining the working depth for sonar. Secondly, it is found that under certain environments there exists a layer of low transmission loss (TL) in the surface duct, whose thickness is related to the source geometry and can be calculated by the Lloyd-mirror method. The receiver should be placed in this layer to minimize the TL. Finally, the arrival angle on a vertical linear array (VLA) in the surface duct is analyzed based on normal mode theory, which provides a priori knowledge of the beam direction of passive sonar.

Key words: surface duct, source-receiver geometry, Lloyd-mirror, normal mode

中图分类号:  (Ray propagation of sound in water)

  • 43.30.Cq
43.30.Bp (Normal mode propagation of sound in water)