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Some factors influencing radiation of sound from flow interaction with edges of finite surfacesEdges of surfaces which are exposed to unsteady flow cause both strictly acoustic effects and hydrodynamic effects, in the form of generation of new hydrodynamic sources in the immediate vicinity of the edge. An analytical model is presented which develops the explicit sound-generation role of the velocity and Mach number of the eddy convection past the edge, and the importance of relative scale lengths of the turbulence, as well as the relative intensity of pressure fluctuations. The Mach number (velocity) effects show that the important paramater is the convection Mach number of the eddies. The effects of turbulence scale lengths, isotropy, and spatial density (separation) are shown to be important in determining the level and spectrum of edge sound radiated for the edge dipole mechanism. Experimental data is presented which provides support for the dipole edge noise model in terms of Mach number (velocity) scaling, parametric dependence on flow field parameter, directivity, and edge diffraction effects.
Document ID
19770016955
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Hayden, R. E. (Bolt, Beranek, and Newman, Inc. Cambridge, MA, United States)
Fox, H. L. (Bolt, Beranek, and Newman, Inc. Cambridge, MA, United States)
Chanaud, R. C. (Bolt, Beranek, and Newman, Inc. Cambridge, MA, United States)
Date Acquired
September 3, 2013
Publication Date
January 1, 1976
Subject Category
Acoustics
Report/Patent Number
BN-2797
NASA-CR-145073
Accession Number
77N23899
Funding Number(s)
CONTRACT_GRANT: NAS1-9559
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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