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The unstable spectrum of swirling gas flows

Leblanc, S. and Le Duc, A. (2005) The unstable spectrum of swirling gas flows. Journal of Fluid Mechanics, 537, pp. 433-442.

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Abstract

The asymptotic structure of the discrete spectrum of a compressible inviscid swirling flow with arbitrary radial distributions of density, pressure and velocity is described for disturbances with large wavenumbers. It is shown that discrete eigenmodes are unstable when a criterion derived by Eckhoff & Storesletten (1978) is satisfied. In general, these modes are characterized by a length scale of order exp(-3ln(m)/4) where m is the azimuthal wavenumber of the disturbance and tends to infinity. They have a spatial structure similar to the incompressible modes obtained by Leibovich & Stewartson (1983). In the particular case of solid-body rotation with a positive gradient of entropy, the unstable discrete spectrum contains modes which scale with exp(-ln(m)/2). If the modes are localized near a solid boundary, they scale with (exp(-3ln(m)/4).

Document Type:Article
Additional Information: LIDO-Berichtsjahr=2005,
Title:The unstable spectrum of swirling gas flows
Authors:
AuthorsInstitution or Email of Authors
Leblanc, S.LSEET, Universität Süd Toulon-Var, Frankreich
Le Duc, A.UNSPECIFIED
Date:2005
Journal or Publication Title:Journal of Fluid Mechanics
Refereed publication:Yes
In ISI Web of Science:Yes
Volume:537
Page Range:pp. 433-442
Status:Published
Keywords:Hydrodynamic stability, swirling, compressible, WKB, asymptotic expansion, continuous spectrum, normal modes, discrete spectrum
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Aeronautics
HGF - Program Themes:Rotorcraft
DLR - Research area:Aeronautics
DLR - Program:L RR - Rotorcraft Research
DLR - Research theme (Project):L - Flight Physics
Location: Köln-Porz , Braunschweig , Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology
Deposited By: Claudia Grant
Deposited On:10 Jan 2006
Last Modified:14 Jan 2010 19:54

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