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An experimental investigation of the composition of jet noise

Published online by Cambridge University Press:  29 March 2006

G. Krishnappa  and
G. T. Csanady
G. Krishnappa
Affiliation:
University of Waterloo, Ontario Present address: National Research Council, Ottawa, Ontario.
G. T. Csanady
Affiliation:
University of Waterloo, Ontario
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Abstract

Noise intensity measurements per octave band have been carried out in the far field of a small circular nozzle, at angles 0-150° from the jet axis, with and without vortex generators. The results, interpreted in the light of recent theoretical conclusions, confirm Lighthill's original suggestion that the dominant noise radiator is the pressure-shear x-r quadrupole at all but the lowest frequencies. At very low frequencies Reynolds stress-shear x-x and x-r quadrupoles contribute comparable amounts of radiation. When the product of Strouhal number (based on nozzle diameter and jet velocity) and jet Mach number exceeds unity the geometrical acoustics approximation becomes valid, but even at such high frequencies the shear noise contribution dominates. Vortex generators, while reducing noise intensity, do not appear to modify drastically the above composition of noise radiators.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 37 , Issue 1 , 5 June 1969 , pp. 149 - 159
Copyright
© 1969 Cambridge University Press

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