Development of a Low-Noise, Low-Turbulence Free Jet Wind Tunnel
1969; Acoustical Society of America; Volume: 46; Issue: 1A_Supplement Linguagem: Inglês
10.1121/1.1972508
ISSN1520-9024
Autores Tópico(s)Wind and Air Flow Studies
ResumoA small-scale free jet wind-tunnel facility for aerodynamic noise studies has been fabricated and installed in the anechoic chamber of the Rye Canyon Acoustics Laboratory of the Lockheed-California Company Research Center. Using wind-tunnel supply air at flow rates up to 20 lb/see, the facility operates at Mach numbers up to 0.4 and Reynolds numbers up to 3×106/ft with a test section whose dimensions are 4×20 in. A unique multiple-jet pressure reducer/muffler has been incorporated into the initial duct section and widespread use made of compressed polyurethane foam for acoustical treatment of duct walls and turning vanes. Damping screens and a honeycomb of soda straws are incorporated in the final settling chamber to reduce turbulence and flow noise. Preliminary measurements have been made of velocity profile at the nozzle exit plane, as well as background noise levels in the settling chamber, at nozzle sidewall, and in the free field of the jet. At M=0.41, variations in velocity profile were less than 0.2% in the core of the jet. Aeolian tones generated by a 12 in. diam. rod in the potential core and in the turbulent mixing region of the jet gave a signal/noise ratio of approximately 10–15 dB, clearly indicating the adequacy of the facility for the study of vortex shedding noise.
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