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Microphone Array Measurements in a Cryogenic Wind Tunnel

Ahlefeldt, Thomas and Koop, Lars (2010) Microphone Array Measurements in a Cryogenic Wind Tunnel. AIAA Journal, Vol. 48 (7), pp. 1470-1479. AIAA. DOI: 10.2514/1.J050083. ISSN 0001-1452.

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Based on previous studies with microphones and electronic equipment in a cryogenic environment, a test array for cryogenic application has been developed. Electret microphones, electronic equipment and fairing material have been successfully tested by the authors under cryogenic conditions and have demonstrated long-term stability. Subsequently, acoustic array measurements performed in a cryogenic wind tunnel for various temperatures in the range 100 K to 300 K using a single rod configuration are described in this paper. The Mach number was in the range 0.1 to 0.3 and the Reynolds number (based on the cylinder diameter of 2.5 mm) was in the range 5·103 to 8·104. The experiments demonstrated the technical feasibility of performing aeroacoustic array measurements at these low temperatures. A systematic study of Reynolds and Mach number effects on the radiated noise of a single rod configuration has been conducted. The results showed reasonably good agreement between theory and measured sound radiation. A Reynolds number dependency of the measured and predicted sound power can be shown.

Document Type:Article
Title:Microphone Array Measurements in a Cryogenic Wind Tunnel
AuthorsInstitution or Email of Authors
Ahlefeldt, ThomasUNSPECIFIED
Koop, Larslars.koop@dlr.de
Date:July 2010
Journal or Publication Title:AIAA Journal
Refereed publication:Yes
In Open Access:No
In ISI Web of Science:Yes
Volume:Vol. 48
Page Range:pp. 1470-1479
Keywords:microphone array, wind tunnel, closed test section, cryogenic wind tunnel, cylinder noise
HGF - Research field:Aeronautics, Space and Transport
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 > Experimental Methods
Deposited By: Ilka Micknaus
Deposited On:15 Dec 2009 08:42
Last Modified:04 Apr 2013 16:16

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