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The low frequency sound from multipole sources in axisymmetric shear flows, with applications to jet noise

Published online by Cambridge University Press:  29 March 2006

M. E. Goldstein
M. E. Goldstein
Affiliation:
National Aeronautics and Space Administration, Lewis Research Center, Cleveland, Ohio 44135
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Abstract

We have obtained a closed-form solution for the sound radiation from multipole sources imbedded in an infinite cylindrical jet with an arbitrary velocity profile. It is valid in the limit where the wavelength is large compared with the jet radius. Simple formulae for the acoustic pressure field due to convected point sources are also obtained. The results show (in a simple way) how the mean flow affects the radiation pattern from the sources. For convected lateral quadrupoles it causes the exponent n of the Doppler factor (1 - M cosθ)−n multiplying the far-field pressure signal to be increased from the value of 3 used by Lighthill to 5.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 70 , Issue 3 , 12 August 1975 , pp. 595 - 604
Copyright
© 1975 Cambridge University Press

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