Rotor-Stator Interaction Noise in Swirling Flow: Stator Sweep and Lean Effects

An asymptotic technique in the limit of large blade and vane number is employed to study the interaction in mean swirling flow of an unsteady rotor wake with a stator row downstream. The effect of various stator characteristics, including stator sweep, lean and number of vanes, on the tone noise rad...

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Bibliographic Details
Published in:AIAA journal 2006-05, Vol.44 (5), p.981-991
Main Authors: Cooper, A. J, Peake, N
Format: Article
Language:English
Subjects:
Acoustics
Aeroacoustics, atmospheric sound
Aerodynamics
Exact sciences and technology
Flow control
Fluid dynamics
Fundamental areas of phenomenology (including applications)
Mathematical models
Noise
Physics
Rotational flow and vorticity
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Summary:An asymptotic technique in the limit of large blade and vane number is employed to study the interaction in mean swirling flow of an unsteady rotor wake with a stator row downstream. The effect of various stator characteristics, including stator sweep, lean and number of vanes, on the tone noise radiated upstream is investigated. The important effects of mean swirl are included in both the rotor wake evolution and the construction of the upstream radiated sound field. Specifically, we construct the first term in the series expansion of the upstream unsteady pressure in inverse powers of the blade count. We show that sweep and lean in suitable combination (positive sweep and positive lean) can lead to this first term becoming zero, so that the upstream radiation is then approximated by the next (smaller) term in the series, and is therefore necessarily reduced. A simple criterion, based on the form of the incident wake at the stator leading edge, which leads to this first term becoming zero, is identified. This provides a very efficient method for assessing the impact of sweep and lean over a wide range of operating conditions. The analytical nature of the model allows the physical mechanism behind the effectiveness of sweep and lean to be identified. [PUBLICATION ABSTRACT]
ISSN:0001-1452
1533-385X
DOI:10.2514/1.5857