Investigation of sonar transponders for offshore wind farms

Modeling approach, experimental setup, and results

authored by: Moritz B. Fricke, Raimund Rolfes
Abstract: The installation of offshore wind farms in the German Exclusive Economic Zone requires the deployment of sonar transponders to prevent collisions with submarines. The general requirements for these systems have been previously worked out by the Research Department for Underwater Acoustics and Marine Geophysics of the Bundeswehr. In this article, the major results of the research project "Investigation of Sonar Transponders for Offshore Wind Farms" are presented. For theoretical investigations a hybrid approach was implemented using the boundary element method to calculate the source directivity and a three-dimensional ray-tracing algorithm to estimate the transmission loss. The angle-dependence of the sound field as well as the weather-dependence of the transmission loss are compared to experimental results gathered at the offshore wind farm alpha ventus, located 45 km north of the island Borkum. While theoretical and experimental results are in general agreement, the implemented model slightly underestimates scattering at the rough sea surface. It is found that the source level of 200 dB re 1 μPa at 1 m is adequate to satisfy the detectability of the warning sequence at distances up to 2 NM (≈ 3.7 km) within a horizontal sector of ±60° if realistic assumptions about signal-processing and noise are made. An arrangement to enlarge the angular coverage is discussed.
Organisation(s): Institute of Structural Analysis
Type: Article
Journal: Journal of the Acoustical Society of America
Volume: 134
Pages: 3536-3545
No. of pages: 10
ISSN: 0001-4966
Publication date: 10.12.2013
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Arts and Humanities (miscellaneous), Acoustics and Ultrasonics
Sustainable Development Goals: SDG 14 - Life Below Water
Electronic version(s): https://doi.org/10.1121/1.4823841 (Access: Unknown)