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airfoil self-noise and predictionA prediction method is developed for the self-generated noise of an airfoil blade encountering smooth flow. The prediction methods for the individual self-noise mechanisms are semiempirical and are based on previous theoretical studies and data obtained from tests of two- and three-dimensional airfoil blade sections. The self-noise mechanisms are due to specific boundary-layer phenomena, that is, the boundary-layer turbulence passing the trailing edge, separated-boundary-layer and stalled flow over an airfoil, vortex shedding due to laminar boundary layer instabilities, vortex shedding from blunt trailing edges, and the turbulent vortex flow existing near the tip of lifting blades. The predictions are compared successfully with published data from three self-noise studies of different airfoil shapes. An application of the prediction method is reported for a large scale-model helicopter rotor, and the predictions compared well with experimental broadband noise measurements. A computer code of the method is given.
Document ID
19890016302
Document Type
Other - NASA Reference Publication (RP)
Authors
Brooks, Thomas F.
(PRC Kentron, Inc., Hampton VA., United States)
Pope, D. Stuart
(PRC Kentron, Inc., Hampton VA., United States)
Marcolini, Michael A.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
September 6, 2013
Publication Date
July 1, 1989
Subject Category
ACOUSTICS
Report/Patent Number
L-16528
NAS 1.61:1218
NASA-RP-1218
Funding Number(s)
PROJECT: RTOP 505-63-51-06
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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