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Quadrupole source in prediction of the noise of rotating blades - A new source descriptionThe aim of this paper is to perform a theoretical study of the quadrupole term of the Ffowcs Williams-Hawkings (FW-H) equation to obtain practical results for applications to rotating blades. The quadrupole term of the FW-H equation is algebraically manipulated into volume, surface and line sources using generalized function theory and differential geometry. The volume source is of the type in Lighthill's jet noise theory. The surface sources are on the blade and shock surfaces and the line source is at the trailing edge. It is shown that contribution of volume sources in the boundary layer and wakes can be written in the form of surface integrals. It is argued that the surface and line sources and the part of the volume sources in the boundary layer, wakes and vortices near the blades should be sufficient in calculation of the noise of high speed rotating blades. The integrals correspoding to the various sources appearing in the formula for calculation of the acoustic pressure are briefly derived.
Document ID
19880031424
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Farassat, F.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
August 13, 2013
Publication Date
October 1, 1987
Subject Category
Acoustics
Report/Patent Number
AIAA PAPER 87-2675
Accession Number
88A18651
Distribution Limits
Public
Copyright
Other

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