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Systematic Comparison of Microphone Array Measurements in Open and Closed Wind Tunnels

Kröber, Stefan und Ehrenfried, Klaus und Koop, Lars und Lauterbach, Andreas und Henning, Arne (2010) Systematic Comparison of Microphone Array Measurements in Open and Closed Wind Tunnels. 16th AIAA/CEAS Aeroacoustics Conference, 7. - 9. Jun. 2010, Stockholm, Sweden. ISBN 978-1-60086-744-6.

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Offizielle URL: http://www.aiaa.org/content.cfm?pageid=230&lumeetingid=2386&viewcon=submit


The phased microphone array has become a widely used tool in aeroacoustic testing for the localisation and quantification of sound sources. The measurements are often carried out in open or closed wind tunnels using scaled models. Test sections in both types of tunnels have advantages and drawbacks when used for aerodynamic and aeroacoustic testing. The closed-test section wind tunnel is normally preferred for measuring aerodynamic properties due to the reduced uncertainties compared with the open section. Conducting aerodynamic and aeroacoustic measurements simultaneously or at least back-to-back helps to reduce wind tunnel access time and costs. Furthermore, in many cases a better microphone array resolution can be achieved because of the shorter distances between array and model. In-flow measurements in closed test sections using flush mounted microphones in the wind tunnel wall are typically subjected to strong hydrodynamic pressure fluctuations induced by the turbulent boundary layer, which can result in a dramatic decrease of the signal-to-noise ratio (SNR). The reverberations in the closed test section are also of concern, since the beamforming accuracy may be affected. In contrast, the open jet acoustic wind tunnel is not plagued by these particular drawbacks. Nevertheless, other problems will occur and can influence the quality of the measurement results. The sound waves have to pass through the wind tunnel shear layer before reaching the microphone. That results in a spatial coherence loss due to turbu- lent scattering and refraction and potentially leads to degraded source maps and under-estimated source levels. In comparison with the closed wind tunnel, far-field measurements can be normally performed.

Dokumentart:Konferenzbeitrag (Vortrag, Paper)
Zusätzliche Informationen:AIAA-2010-3734
Titel:Systematic Comparison of Microphone Array Measurements in Open and Closed Wind Tunnels
AutorenInstitution oder E-Mail-Adresse der Autoren
Henning, ArneTU-Berlin
Referierte Publikation:Nein
In ISI Web of Science:Nein
Band:Vol. 15
Seitenbereich:Seiten 1-8
Name der Reihe:AIAA Meeting Papers on Disc (DVD-ROM)
Stichwörter:microphone array measurement, open and closed wind tunnels, beamforming accuracy
Veranstaltungstitel:16th AIAA/CEAS Aeroacoustics Conference
Veranstaltungsort:Stockholm, Sweden
Veranstaltungsart:internationale Konferenz
Veranstaltungsdatum:7. - 9. Jun. 2010
Veranstalter :AIAA
HGF - Forschungsbereich:Verkehr und Weltraum (alt)
HGF - Programm:Luftfahrt
HGF - Programmthema:Starrflügler
DLR - Schwerpunkt:Luftfahrt
DLR - Forschungsgebiet:L AR - Starrflüglerforschung
DLR - Teilgebiet (Projekt, Vorhaben):L - Flugphysik
Standort: Göttingen
Institute & Einrichtungen:Institut für Aerodynamik und Strömungstechnik > Hubschrauber
Institut für Aerodynamik und Strömungstechnik > Experimentelle Verfahren
Hinterlegt von: Ilka Micknaus
Hinterlegt am:21 Jul 2010 14:12
Letzte Änderung:21 Jul 2010 14:12

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