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Airfoil Self-Noise and Prediction

Airfoil Self-Noise and Prediction PDF Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722933173
Category :
Languages : en
Pages : 146

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Book Description
A 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. Brooks, Thomas F. and Pope, D. Stuart and Marcolini, Michael A. Langley Research Center AEROACOUSTICS; AERODYNAMIC NOISE; AIRFOIL PROFILES; AIRFOILS; BLADE-VORTEX INTERACTION; BOUNDARY LAYER SEPARATION; BOUNDARY LAYERS; NOISE PREDICTION (AIRCRAFT); VORTEX SHEDDING; AERODYNAMIC STALLING; APPLICATIONS PROGRAMS (COMPUTERS); NOISE MEASUREMENT; NOISE SPECTRA; ROTARY WINGS; STROUHAL NUMBER; TRAILING EDGES; VORTICES; WIND TUNNEL TESTS...