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Investigation of the systematic phase mismatch in microphone-array analysis

Koop, Lars and Ehrenfried, Klaus and Kröber, St. (2005) Investigation of the systematic phase mismatch in microphone-array analysis. AIAA. 11th AIAA/CEAS Aeroacoustics Conference, 2005-05-23 - 2005-05-25, Monterey, CA (USA). ISBN 1-56347-761-0.

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The paper investigates phase deviations as they occur in aeroacoustic array measurements in open jet wind tunnels. The accuracy of an approximative zero-thickness shear layer model, which is used in practice to predict the phase shift between source and microphones, is investigated numerically. The exact wave propagation through a generic shear layer is calculated by solving the full linearized Euler equations using a finite element method and by means of geometrical acoustics. The results are taken to determine the phase deviations between the simplified model and the exact case. It is demonstrated that the position of the zero-thickness shear layer is important for the accuracy at high frequencies. Additionally measurements are made to analyze the phase fluctuations which are generated by the scattering at turbulent structures in the open-jet shear layer. A procedure is proposed to compensate these phase fluctuations and to improve the array efficiency.

Document Type:Conference or Workshop Item (Speech, Paper)
Additional Information: LIDO-Berichtsjahr=2005, monograph_id=AIAA 2005-2962,
Title:Investigation of the systematic phase mismatch in microphone-array analysis
AuthorsInstitution or Email of Authors
Ehrenfried, KlausUNSPECIFIED
Kröber, St.TU-Berlin
Refereed publication:No
In ISI Web of Science:No
Volume:Vol. 10
Page Range:pp. 1-18
Series Name:CD-ROM Conference Proceedings
Keywords:microphone array, phase mismatch, shear layer, open test section, phase calibration, linearized Euler equation, ray acoustics
Event Title:11th AIAA/CEAS Aeroacoustics Conference
Event Location:Monterey, CA (USA)
Event Type:international Conference
Event Dates:2005-05-23 - 2005-05-25
Organizer:American Institute of Aeronautics and Astronautics
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Aeronautics
HGF - Program Themes:Aircraft Research
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Flight Physics
Location: Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Helicopters
Institute of Aerodynamics and Flow Technology > Experimental Methods
Deposited By: Ilka Micknaus
Deposited On:11 Jul 2007
Last Modified:14 Jan 2010 19:50

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