Kolloquiumsvortrag, (ET/IT), Dr. Jan Abshagen, Wehrtechnische Dienststelle für Schiffe und Marinewaffen, Maritime Technologie und Forschung - WTD 71. / am 16.04.2018

16.04.2018 von 17:15 bis 18:00

Institute Ostufer, Geb. D, "Aquarium", Kaiserstr. 2, 24143 Kiel

Titel: Flow-induced Noise in Hydroacoustic Sensor Systems

Abstract: Sound can propagate over a large distance in the sea without significant attenuation and is therefore of unique importance in underwater communication, navigation, and detection. Underwater sound is received in these applications with hydroacoustic sensor systems that are often attached to or towed behind a vessel. The turbulent flow that forms around the hull of the moving sensor system induces hydroacoustic noise in the interior that dominates the noise level (and therefore limits the performance) at larger speeds due to the strong speed dependence of flow acoustic sources (e.g. Lighthill’s v8-law). In a series of research cruises in recent years the statistical properties and underlying physical mechanisms of interior hydroacoustic noise induced from outer turbulent flows have been investigated under sea conditions with towed measurement systems. The talk will focus on the spatio-temporal correlation of the turbulent noise sources as well as the filter properties of the mechanical hull structure and the embedded hydrophones. The analysis is predominantly performed in wavenumber-frequency space. New developments in piezoelectric thin-film sensor technology allow in principle the design of specific wavenumber filters for flow noise reduction. The potential of such sensors for future underwater applications is discussed.

Prof. Schdmidt

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