Rotorcraft Aeroacoustics Computations with Overset‐Grid CFD Methods
Abstract:This paper describes a new method for computing the flowfield and acoustic signature of arbitrary rotors in forward flight. The overall scheme solves the Navier‐Stokes equations on a system of overset grids. These grids allow for prescribed cyclic and flapping blade motions and capture the interactions between the rotor blades and wake. The far‐lield noise is computed with an acoustic integral over a surface that completely encloses the rotor blades. Interpolations onto this acoustic surface use the same overset‐grid techniques that are used for the flowfield solution. As a demonstration of the overall prediction scheme, computed and experimental far‐field noise results are compared in cases with high‐speed impulsive (HSI) and blade‐vortex interaction (BVI) noise. Computed HSI noise shows excellent agreement with experimental data in the plane of the rotor. Out‐of‐plane HSI and BVI predictions require improved grid resolution in the rotor wake to capture the details of the high‐frequency loading noise.
Document Type: Research Article
Affiliations: Army/NASA Rotorcraft Division, Aeroflightdynamics Directorote (AVRDEC), US Army Aviation and Missile Command, Ames Research Center, Moffett Field, CA
Publication date: April 1, 1999
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