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Emission of Sound from Turbulence Convected by a Parallel Mean Flow in the Presence of a Confining DuctAn approximate method for calculating the noise generated by a turbulent flow within a semi-infinite duct of arbitrary cross section is developed. It is based on a previously derived high-frequency solution to Lilley's equation, which describes the sound propagation in a transversely-sheared mean flow. The source term is simplified by assuming the turbulence to be axisymmetric about the mean flow direction. Numerical results are presented for the special case of a ring source in a circular duct with an axisymmetric mean flow. They show that the internally generated noise is suppressed at sufficiently large upstream angles in a hard walled duct, and that acoustic liners can significantly reduce the sound radiated in both the upstream and downstream regions, depending upon the source location and Mach number of the flow.
Document ID
20000000186
Acquisition Source
Glenn Research Center
Document Type
Reprint (Version printed in journal)
Authors
Goldstein, Marvin E. (NASA Glenn Research Center Cleveland, OH United States)
Leib, Stewart J. (Ohio Aerospace Inst. Brook Park, OH United States)
Date Acquired
September 7, 2013
Publication Date
January 1, 1999
Subject Category
Acoustics
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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