Acoustic upgrades to wind tunnels at the National Research Council Canada

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Proceedings title18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference)
Conference18th AIAA/CEAS Aeroacoustics Conference 2012 (33rd AIAA Aeroacoustics Conference), 4 June 2012 through 6 June 2012
SubjectAcoustic environment; Acoustic treatment; Aerospace configurations; Aircraft manufacturers; Array measurements; National Research Council; Reduction strategy; Stainless steel mesh; Aeroacoustics; Aircraft; Airframes; Landing gear (aircraft); Microphones; Noise abatement; Research; Structural frames; Wind tunnels; Acoustic noise
AbstractAirframe noise is growing a concern for aircraft manufacturers, operators and commu- nities. The ability to determine the location and strength of noise sources on an aircraft or its components allows noise reduction strategies to be developed which can have sig- nificant impact on the overall noise signature of the aircraft. Phased-microphone array measurement technologies have become an effective tool in noise source localization for aerospace configurations. With the growing national need to address airframe noise is- sues, the National Research Council Canada upgraded two of its wind tunnels to provide a better acoustic environment to make phased-array measurements. The first facility to be upgraded in 2009 was the 0.9m 3/4-open jet low speed research tunnel in which the original metal turning vanes on the corners bounding the test section were replaced with vanes lined with acoustic foam. This reduced the background noise in the test section by 5 - 10dB depending upon the frequency with little reduction in maximum tunnel speed. The second facility to receive an acoustic treatment was the 2m x 3m closed circuit tunnel in 2011. For this facility, an acoustic liner was developed for the test section which allowed the microphones to be recessed out of the flow and decreased the reverberant nature of the hard-walled tunnel. All walls of the tunnel were covered with acoustic foam-filled boxes covered with a stainless steel mesh. This reduced the background noise measured by the recessed microphone array by 15 - 20dB compared to a flush mounted array. In each up-graded facility, an aeroacoustic test of a two-wheel main landing gear of a business jet was carried out (the first at 1/3rd-scale and the second at full scale). Results in the large tunnel show accurate noise source localization with repeatability of 0.15dB for the loudest source and 0.25dB for the second loudest noise source. The two successful wind tunnel entries show the effectiveness of the two wind tunnel acoustic upgrades. © 2012 by Government of Canada.
Publication date
AffiliationNational Research Council Canada (NRC-CNRC); Aerospace (AERO-AERO)
Peer reviewedYes
NPARC number21269511
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Record identifier439992e5-035b-40a9-b7e3-2140a07ca86c
Record created2013-12-12
Record modified2016-05-09
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