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On the scaling of small-scale jet noise to large scaleAn examination was made of several published jet noise studies for the purpose of evaluating scale effects important to the simulation of jet aeroacoustics. Several studies confirmed that small conical jets, one as small as 59 mm diameter, could be used to correctly simulate the overall or perceived noise level (PNL) noise of large jets dominated by mixing noise. However, the detailed acoustic spectra of large jets are more difficult to simulate because of the lack of broad-band turbulence spectra in small jets. One study indicated that a jet Reynolds number of 5 x 10(exp 6) based on exhaust diameter enabled the generation of broad-band noise representative of large jet mixing noise. Jet suppressor aeroacoustics is even more difficult to simulate at small scale because of the small mixer nozzles with flows sensitive to Reynolds number. Likewise, one study showed incorrect ejector mixing and entrainment using a small-scale, short ejector that led to poor acoustic scaling. Conversely, fairly good results were found with a longer ejector and, in a different study, with a 32-chute suppressor nozzle. Finally, it was found that small-scale aeroacoustic resonance produced by jets impacting ground boards does not reproduce at large scale.
Document ID
19950028567
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Soderman, Paul T.
(NASA Ames Research Center Moffett Field, CA, United States)
Allen, Christopher S.
(Sterling Federal Systems, Moffett Field, CA United States)
Date Acquired
August 16, 2013
Publication Date
May 1, 1992
Subject Category
Acoustics
Report/Patent Number
AIAA PAPER 92-02109
Accession Number
95A60166
Distribution Limits
Public
Copyright
Other

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