Rotor Broadband Noise Prediction with Comparison to Model Data

This paper reports an analysis and prediction BTE development of rotor broadband noise. The two BVI primary components of this noise are Blade-Wake BWI Interaction (BWI) noise, due to the blades' interaction C with the turbulent wakes of the preceding blades, and CT "Self" noise, due to the development and shedding of co turbulence within the blades' boundary layers. -Emphasized in this report is the new code development Dh_ for Self noise. The analysis and validation employs DI data from the HART program, a model BO-105 rotor f wind tunnel test conducted in the German-Dutch Wind Tunnel (DNW). The BWI noise predictions are based f on measured pressure response coherence functions f_ using cross-spectral methods. The Self noise predictions are based on previously reported semiG empirical modeling of Self noise obtained from isolated H airfoil sections and the use of CAMRAD.Modl to define rotor performance and local blade segment flow LBL-VS conditions. Both BW1 and Self noise from individual LE blade segments are Doppler shifted and summed at the L observer positions. Prediction comparisons with M measurements show good agreement for a range of R rotor operating conditions from climb to steep descent. Re c The broadband noise predictions, along with those of r harmonic and impulsive Blade-Vortex Interaction r (BVI) noise predictions, demonstrate a significant advance in predictive capability for main rotor noise. SPL TBL-TE TE tr U Vml! * SeniorResearch Scientist,AeroacousticsBranch, Vwt Associate Fellow AIAA. V t Senior Research Scicntist, Acroacoustics Branch X, X' Copyright © 2001 by the American Institute of Aeronautics and Astronautics, Inc. No copyright is asserted in thc United States under Xe Title 17,U.S. Code. The U.S, Government has a royalty-free license to excrcisc all rights under the copyright claimed herein for government purposes. All other rights are reserved by the copyright X T

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