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Interaction of aerodynamic noise with laminar boundary layers in supersonic wind tunnelsThe interaction between incoming aerodynamic noise and the supersonic laminar boundary layer is studied. The noise field is modeled as a Mach wave radiation field consisting of discrete waves emanating from coherent turbulent entities moving downstream within the supersonic turbulent boundary layer. The individual disturbances are likened to miniature sonic booms and the laminar boundary layer is staffed by the waves as the sources move downstream. The mean, autocorrelation, and power spectral density of the field are expressed in terms of the wave shapes and their average arrival rates. Some consideration is given to the possible appreciable thickness of the weak shock fronts. The emphasis in the interaction analysis is on the behavior of the shocklets in the noise field. The shocklets are shown to be focused by the laminar boundary layer in its outer region. Borrowing wave propagation terminology, this region is termed the caustic region. Using scaling laws from sonic boom work, focus factors at the caustic are estimated to vary from 2 to 6 for incoming shocklet strengths of 1 to .01 percent of the free stream pressure level. The situation regarding experimental evidence of the caustic region is reviewed.
Document ID
19840012713
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Schopper, M. R.
(Systems and Applied Sciences Corp. Hampton, VA, United States)
Date Acquired
September 4, 2013
Publication Date
April 1, 1984
Publication Information
Publisher: NASA
Subject Category
Fluid Mechanics And Heat Transfer
Report/Patent Number
NAS 1.26:3621
NASA-CR-3621
Accession Number
84N20781
Funding Number(s)
PROJECT: RTOP 505-31-23-03
CONTRACT_GRANT: NAS1-16572
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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