NDLI: Refraction and scattering of sound by a shear layer

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Refraction and scattering of sound by a shear layer

Content Provider	NASA Technical Reports Server (NTRS)
Author	Schlinker, R. H. Amiet, R. K.
Copyright Year	1980
Description	The angle and amplitude changes for acoustic waves refracted by a circular open jet shear layer were determined. The generalized refraction theory was assessed experimentally for on axis and off axis acoustic source locations as source frequency varied from 1 kHz to 10 kHz and free stream Mach number varied from 0.1 to 0.4. Angle and amplitude changes across the shear layer show good agreement with theory. Experiments confirm that the refraction theory is independent of shear layer thickness, acoustic source frequency, and source type. A generalized theory is, thus, available for correcting far field noise data acquired in open jet test facilities. The effect of discrete tone scattering by the open jet turbulent shear layer was also studied. Scattering effects were investigated over the same Mach number range as frequency varied from 5 kHz to 15 kHz. Attenuation of discrete tone amplitude and tone broadening were measured as a function of acoustic source position and radiation angle. Scattering was found to be stronger at angles close to the open jet axis than at 90 deg, and becomes stronger as the acoustic source position shifts downstream. A scattering analysis provided an estimate of the onset of discrete tone scattering.
File Size	5762538
Page Count	192
File Format	PDF
Alternate Webpage(s)	http://archive.org/details/NASA_NTRS_Archive_19810008332
Archival Resource Key	ark:/13960/t1jh8c887
Language	English
Publisher Date	1980-12-01
Access Restriction	Open
Subject Keyword	Acoustics Shear Layers Turbulence Sound Propagation Acoustic Scattering Refracted Waves Frequencies Acoustic Attenuation Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science
Content Type	Text
Resource Type	Technical Report

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