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Acoustic Resonances and Trapped Modes in Annular Plate Cascades

Koch, Werner (2009) Acoustic Resonances and Trapped Modes in Annular Plate Cascades. Journal of Fluid Mechanics, 628 (06), pp. 155-180. Cambridge University Press. DOI: 10.1017/s0022112009006144. ISSN 0022-1120.

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Official URL: http://journals.cambridge.org


As a stepping stone towards understanding acoustic resonances in axial flow compressors acoustic resonances are computed numerically in fixed single and tandem plate cascades in an infinitely long annular duct. Applying perfectly matched layer absorbing boundary conditions in the form of the complex scaling method of atomic and molecular physics to approximate the radiation condition the resonance problem is transformed into an eigenvalue problem. Of particular interest are resonances with zero radiation damping (trapped modes) or very small radiation damping (nearly trapped modes). Such resonances can be excited by wakes from compressor cascades or struts. If the shedding frequency is sufficiently close to an acoustic resonant frequency the latter may control the vortex shedding causing high intensity tonal noise or occasionally even blade failure. All resonances are computed for zero mean flow approximating low Mach number flows. The influence of various cascade parameters on the resonant frequencies is studied and, whenever possible, our numerical results are compared with published experimental findings.

Document Type:Article
Title:Acoustic Resonances and Trapped Modes in Annular Plate Cascades
AuthorsInstitution or Email of Authors
Koch, Wernerwerner.koch@dlr.de
Date:June 2009
Journal or Publication Title:Journal of Fluid Mechanics
Refereed publication:Yes
In Open Access:No
In ISI Web of Science:Yes
Page Range:pp. 155-180
Publisher:Cambridge University Press
Keywords:acoustic resonances, trapped modes, annular cascades, compressor acoustics
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:L VU - Air Traffic and Environment (old)
DLR - Research area:Aeronautics
DLR - Program:L VU - Air Traffic and Environment
DLR - Research theme (Project):L - Quiet Air Traffic (old), L - Fan and Compressor Technologies (old)
Location: Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Helicopters
Deposited By: Elisabeth Winkels
Deposited On:09 Jul 2009 12:13
Last Modified:26 Mar 2015 10:10

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