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Low-frequency sound propagation in a quasi-one-dimensional flow

Published online by Cambridge University Press:  20 April 2006

R. Mani
R. Mani
Affiliation:
General Electric Company, Corporate Research and Development, Schenectady, New York 12301, U.S.A.
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Abstract

A systematic low-frequency theory is developed for the propagation of one-dimensional sound waves in a variable-area duct. The mean flow in the duct is assumed to be isentropic, compressible, and one-dimensional. Two applications are made of the theory. One concerns the reflexion coefficient from a pipe-nozzle combination, in which case comparisons are also made with some experimental data. In the second application, we consider the case of a sonic throat separating subsonic and supersonic flow. In this case, if the mean Mach number distribution in addition to being unity at the throat is also stationary at the throat, there is an axial ‘boundary-layer’ region in which the impedance of the sound wave changes from a fundamentally unsteady (reflexion-free) value at the sonic throat to the quasi-steady value away from the throat.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 104 , March 1981 , pp. 81 - 92
Copyright
© 1981 Cambridge University Press

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