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Abstract

The impact of the noise radiated from merchant ships on marine life has become an active area of research. In this paper, a methodology integrating observation at a single location and modelling the whole noise field in shallow waters is presented. Specifically, underwater radiated noise data of opportunistic merchant ships in the waters of Zhoushan Archipelago were collected at least one day in each month from January 2015 to November 2016. The noise data were analyzed and a modified empirical spectral source level (SSL) model of merchant ships was proposed inspired by the RANDI-3 model (Research Ambient Noise Directionality) methodology. Then combining the modified model with the realistic geoacoustic parameters and AIS data of observed merchant ships, the noise mappings in this area were performed with NĂ—2D of Normal Mode calculations, in which the SSL of each ship was estimated using the modified model. The sound propagation at different receiving positions is different due to the shielding effect of islands and bottom topography. The methodology proposed in this paper may provide a reference for modelling shipping noise in shallow waters with islands and reefs.
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Authors and Affiliations

Zilong Peng
1
Fulin Zhou
2
Jun Fan
2
Bin Wang
2
ORCID: ORCID
Huabing Wen
1

  1. Institute of Noise and Vibration, School of Energy and Power Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, People’s Republic of China
  2. Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China
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Abstract

Using the tunderwater corner reflector (CR) to simulate the acoustic scattering characteristics of the military target is a new technology to counter active sonar detection. Existing underwater CRs only have the ability to interfere with the acoustic field, but have limitations in acoustic wave modulation. Therefore, acoustic metasurfaces applied on CRs to enhance the ability of acoustic wave modulation has a great application prospect. A fast prediction method based on the Kirchhoff approximation (KA) and the ray tracing theory is proposed to calculate the acoustic scattering characteristics of CR with acoustic metasurfaces in grooves array type. The accuracy of the method is verified by the finite element method (FEM) simulation. The modulation effect of CR with grooves array in different gradient combinations on the structural scattering acoustic field is analyzed. The research shows that the CR with different combinations of the acoustic metasurface has an obvious modulation effect on the amplitude of the acoustic waves and the deflection of acoustic field. In particular, the grooves array in combination with positive and negative gradients has an obvious deflection impact on the scattering acoustic field.
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Authors and Affiliations

Jiaman Du
1
Zilong Peng
1
Lili Ge
1
Shijin Lyu
1 2
Fulin Zhou
3
Yan Liu
4
ORCID: ORCID

  1. School of Energy and Power Engineering Jiangsu University of Science and Technology, Zhenjiang, China
  2. National Key Laboratory on Ship Vibration and Noise, China Ship Science Research Center, Wuxi, China
  3. School of Naval Architecture, Ocean and Civi Engineering, Shanghai Jiao Tong University, Shanghai, China
  4. Shanghai Research Institute of Materials, Shanghai, China

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