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Aerodynamic noise emission from turbulent shear layers

Published online by Cambridge University Press:  29 March 2006

S. P. Pao
S. P. Pao
Affiliation:
University of Alabama, Huntsville
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Abstract

The Phillips (1960) convected wave equation is employed in this paper to study aerodynamic noise emission processes in subsonic and supersonic shear layers. The wave equation in three spatial dimensions is first reduced to an ordinary differential equation by Fourier transformation, then solved via the WKBJ method. Three typical solutions are required for discussions in this paper. The current results are different from the classical conclusions. The effects of refraction, convection, Mach-number dependence and temperature dependence of turbulent noise emission are analysed in the light of solutions to the Phillips equation. Owing to the inherent restrictions of the WKBJ transformation, the results of the present paper should be applied to wave radiation from shear layers whose thickness is no less than approximately one quarter of a wavelength. Such a condition is satisfied for turbulent round jets with an exit velocity greater than 0·6 times the ambient speed of sound.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 59 , Issue 3 , 17 July 1973 , pp. 451 - 479
Copyright
© 1973 Cambridge University Press

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