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Simulation of Acoustic Scattering from a Trailing EdgeThree model problems were examined to assess the difficulties involved in using a hybrid scheme coupling flow computation with the the Ffowcs Williams and Hawkings equation to predict noise generated by vortices passing over a sharp edge. The results indicate that the Ffowcs Williams and Hawkings equation correctly propagates the acoustic signals when provided with accurate flow information on the integration surface. The most difficult of the model problems investigated inviscid flow over a two-dimensional thin NACA airfoil with a blunt-body vortex generator positioned at 98 percent chord. Vortices rolled up downstream of the blunt body. The shed vortices possessed similarities to large coherent eddies in boundary layers. They interacted and occasionally paired as they convected past the sharp trailing edge of the airfoil. The calculations showed acoustic waves emanating from the airfoil trailing edge. Acoustic directivity and Mach number scaling are shown.
Document ID
20040086818
Acquisition Source
Langley Research Center
Document Type
Conference Paper
Authors
Singer, Bart A. (NASA Langley Research Center Hampton, VA, United States)
Brentner, Kenneth S. (NASA Langley Research Center Hampton, VA, United States)
Lockard, David P. (NASA Langley Research Center Hampton, VA, United States)
Lilley, Geoffrey M. (Institute for Computer Applications in Science and Engineering Hampton, VA, United States)
Date Acquired
September 7, 2013
Publication Date
January 1, 1999
Subject Category
Aircraft Propulsion And Power
Report/Patent Number
AIAA Paper 99-0231
Meeting Information
Meeting: Aerospace Sciences Meeting and Exhibit
Location: Reno, NV
Country: United States
Start Date: January 11, 1999
End Date: January 14, 1999
Distribution Limits
Public
Copyright
Public Use Permitted.

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