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Directional Attenuation of Jet Noise With Eccentric Coannular Nozzle InvestigatedJet noise and flow field were measured to follow up on observations made by Professor D. Papamoschou of the University of California at Irvine (NASA Grant NAG3-2345). When a dual-stream coannular nozzle was arranged non-concentrically, noise was attenuated significantly on the side where the annulus was thicker. A similar observation was also made in reference 2. The practical significance is obvious. If the bypass flow of a jet exhaust in flight could be diverted to form a thicker layer underneath, then less noise would be heard by an observer on the ground. In view of the current emphasis on jet noise abatement, researchers felt that the effect deserved further attention. This prompted an experiment to confirm the phenomenon in a larger facility and to obtain flow-field data to advance understanding of the mechanism.
Document ID
20050217471
Document Type
Other
Authors
Zaman, Khairul B.
(NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
September 7, 2013
Publication Date
June 1, 2005
Publication Information
Publication: Research and Technology 2004
Subject Category
Aircraft Design, Testing And Performance
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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IDRelationTitle20050228985Analytic PrimaryResearch and Technology 2004