Accession Number : ADA294477

Title :   Effect of Wake Structure on Blade-Vortex Interaction Phenomena: Acoustic Prediction and Validation,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER

Personal Author(s) : Gallman, Judith M. ; Tung, Chee ; Schultz, Klaus J. ; Splettstoesser, Wolf ; Buchholz, Heino

PDF Url : ADA294477

Report Date : 1995

Pagination or Media Count : 15

Abstract : During the Higher Harmonic Control Aeroacoustic Rotor Test, extensive measurements of the rotor aerodynamics, the far-field acoustics, the wake geometry and the blade motion for powered, descent, flight conditions were made. These measurements have been used to validate and improve the prediction of blade-vortex interaction (BVI) noise. The improvements made to the BVI modeling after the evaluation of the test data are discussed. The effects of these improvements on the acoustic-pressure predictions are shown. These improvements include re-structuring the wake, modifying the core size, incorporating the measured blade motion into the calculations and attempting to improve the dynamic blade response. A comparison of four different implementations of the Ffowcs Williams and Hawkings equation is presented. A common set of aerodynamic input has been used for this comparison. (AN)

Descriptors :   *VORTICES, *WAKE, *ACOUSTIC FIELDS, TEST AND EVALUATION, MATHEMATICAL MODELS, EXPERIMENTAL DATA, PREDICTIONS, VALIDATION, COMPARISON, DYNAMIC RESPONSE, AIR FLOW, MOTION, ROTOR BLADES(ROTARY WINGS), FAR FIELD, HELICOPTERS, AERODYNAMIC LOADING, FLOW NOISE, ACOUSTIC DATA, SOUND PRESSURE, PRESSURE DISTRIBUTION, DYNAMIC PRESSURE, GAS SURFACE INTERACTIONS, DESCENT.

Subject Categories : Aerodynamics
      Fluid Mechanics
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE