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Array Measurements in Wind Tunnels with open Test Sections

Lauterbach, Andreas and Ehrenfried, Klaus and Koop, Lars (2008) Array Measurements in Wind Tunnels with open Test Sections. bebec2008 Berlin Beamforming Conference, 2008-02-19 - 2008-02-20, Berlin. ISBN 978-3-00-023849-9.

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Abstract

Acoustically optimized wind tunnels usually have an anechoic chamber around an open test section. For array measurements in this type of tunnels the acoustic array is typically placed outside the flow field - beside or above the test section. The sound emitted from sources in the flow has to propagate through a turbulent shear layer to reach the microphones. During their passage through the shear layer the sound waves interact with turbulent structures. The higher the frequency of the wave, the more significant the effect of the shear layer is. In the present paper these interaction of sound waves with a turbulent shear layer is investigated. It is analyzed which effects can occur when sound waves propagate through a turbulent shear layer and how these effects can influence the results of array measurements. Experiments with a test source in a wind tunnel with open test section are performed. It is shown that turbulent structures in the shear layer lead to systematic phase fluctuations. These phase fluctuations have a certain spectrum and a distinct spatial correlation. Beside these effects the spectral broadening of tones due to the propagation trough the shear layer is investigated.

Document Type:Conference or Workshop Item (Speech)
Title:Array Measurements in Wind Tunnels with open Test Sections
Authors:
AuthorsInstitution or Email of Authors
Lauterbach, AndreasUNSPECIFIED
Ehrenfried, KlausUNSPECIFIED
Koop, LarsUNSPECIFIED
Date:11 February 2008
Refereed publication:No
In ISI Web of Science:No
ISBN:978-3-00-023849-9
Status:Published
Keywords:microphone array, wind tunnel, shear layer, phase fluctuations, broadening
Event Title:bebec2008 Berlin Beamforming Conference
Event Location:Berlin
Event Type:national Conference
Event Dates:2008-02-19 - 2008-02-20
Organizer:DLR, TU - Berlin, GFaI
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:L VU - Air Traffic and Environment (old)
DLR - Research area:Aeronautics
DLR - Program:L VU - Air Traffic and Environment
DLR - Research theme (Project):L - Quiet Air Traffic (old)
Location: Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Helicopters
Institute of Aerodynamics and Flow Technology > Experimental Methods
Deposited By: Andreas Lauterbach
Deposited On:03 Mar 2008
Last Modified:12 Dec 2013 20:29

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