Campus Units

Aerospace Engineering

Document Type

Article

Publication Version

Submitted Manuscript

Publication Date

8-5-2013

Journal or Book Title

Journal of Sound and Vibration

Volume

332

Issue

16

First Page

3832

Last Page

3845

DOI

10.1016/j.jsv.2013.02.027

Abstract

A numerical approach for predicting tonal aerodynamic noise from ‘‘open rotors’’ is presented. ‘‘Open rotor’’ refers to an engine architecture with a pair of counter-rotating propellers. Typical noise spectra from an open rotor consist of dominant tones, which arise due to both the steady loading/thickness and the aerodynamic interaction between the two bladerows. The proposed prediction approach utilizes Reynolds Averaged Navier–Stokes (RANS) Computational Fluid Dynamics (CFD) simulations to obtain near- field description of the noise sources. The near-to-far-field propagation is then carried out by solving the Ffowcs Williams–Hawkings equation. Since the interest of this paper is limited to tone noise, a linearized, frequency domain approach is adopted to solve the wake/vortex–blade interaction problem. This paper focuses primarily on the speed scaling of the aerodynamic tonal noise from open rotors. Even though there is no theoretical mode cut-off due to the absence of nacelle in open rotors, the far-field noise is a strong function of the azimuthal mode order. While the steady loading/thickness noise has circumferential modes of high order, due to the relatively large number of blades (~10-12), the interaction noise typically has modes of small orders. The high mode orders have very low radiation efficiency and exhibit very strong scaling with Mach number, while the low mode orders show a relatively weaker scaling. The prediction approach is able to capture the speed scaling (observed in experiment) of the overall aerodynamic noise very well.

Comments

This is a manuscript of an article from The Journal of Sound and Vibration 332 (2013): 3832, doi: 10.1016/j.jsv.2013.02.027. Posted with permission.

Copyright Owner

Elsevier Inc.

Language

en

File Format

application/pdf

Published Version

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