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Acoustic Resonances in a 2D High Lift Configuration and 3D Open Cavity

Hein, S. and Koch, W. and Schöberl, J. (2005) Acoustic Resonances in a 2D High Lift Configuration and 3D Open Cavity. In: AIAA Paper 2005-2867, pp. 1-15. 11th AIAA/CEAS Aeroacoustics Conference, Monterey/CA, 23.-25.5.2005.

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Abstract

Acoustic resonances are computed numerically for a generic two-dimensional three-element high lift configuration and a three-dimensional open cavity. Both are major sources of tonal airframe noise. All computations are made for zero mean flow. The high-order finite element code NGSolve of Joachim Schöberl is used in conjunction with Perfectly Matched Layer (PML) absorbing boundary conditions to avoid unphysical reflections at the necessarily finite grid boundaries. Whatever the actual source of the observed discrete tones is, these tones may be enhanced by or lock onto resonant acoustic frequencies. For the high lift configuration our computed resonant frequencies are indeed fairly close to experimentally observed low-frequency slat tones and may be interpreted as resonances of leaky surface waves. These low-frequency resonances are practically unaffected by changes in slat cove geometry contrary to high-frequency resonances (gap tones). The radiation loss of resonances in a three-dimensional open cavity was found to be lower than in a two-dimensional cavity and a confining duct can change the damping of cavity resonances.

Document Type:Conference or Workshop Item (Paper)
Additional Information: LIDO-Berichtsjahr=2005,
Title:Acoustic Resonances in a 2D High Lift Configuration and 3D Open Cavity
Authors:
AuthorsInstitution or Email of Authors
Hein, S.UNSPECIFIED
Koch, W.UNSPECIFIED
Schöberl, J.Johannes Kepler Universität Linz
Date:2005
Journal or Publication Title:AIAA Paper 2005-2867
Page Range:pp. 1-15
Status:Published
Keywords:airframe noise, slat noise, cavity noise, acoustic resonances
Event Title:11th AIAA/CEAS Aeroacoustics Conference, Monterey/CA, 23.-25.5.2005
Organizer:American Institute of Aeronautics and Astronautics
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Aeronautics
HGF - Program Themes:Aircraft Research
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Flight Physics
Location: Köln-Porz , Braunschweig , Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology
Deposited By: elib DLR-Beauftragter
Deposited On:31 Jan 2006
Last Modified:14 Jan 2010 19:54

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