25th Congress of International Council of the Aeronautical Sciences, 3 - 8 September 2006, Hamburg, Germany
Paper ICAS 2006-2.10.4

ON THE CORRELATION OF ACOUSTIC MODES IN A NOZZLE AND IN THE FAR-FIELD

L. M. B. C. Campos, J. M. G. S. Oliveira
Instituto Superior Técnico, Portugal

Keywords: duct, impedance, noise attenuation, sound radiation

Circumferentially non-uniform liners has been shown to attenuate the acoustic amplitude of some of the modes present in the duct. In this paper the far-field acoustic pressure field radiated from the exit of a lined cylindrical duct is considered and the case of uniform and circumferentially non-uniform liners compared.

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