Accéder directement au contenu Accéder directement à la navigation
Article dans une revue

A cavity-by-cavity description of the aeroacoustic instability over a liner with a grazing flow

Abstract : This paper presents a two-dimensional (2D) cavity-by-cavity description of a convective instability near a lined wall with low dissipation due to the coupling of hydrodynamic modes with resonance of the wall. For a liner consisting of an array of deep cavities periodically placed along a duct containing a mean shear flow, the acoustic and hydrodynamic disturbances are described by the linearized Euler equations. The Bloch modes and the scattering matrix of periodic cells are used to examine the instability over the liner. The unstable Bloch mode is due to the coupling of a hydrodynamic mode in the shear flow with the cavity resonance. It is demonstrated that even when all the transverse modes are stable in the duct-cavity system, i.e. when the Kelvin-Helmholtz instability of the shear flow over the cavities does not occur, such an instability over the liner can still exist. The unstable Bloch wave, excited by the incident sound wave at the upstream part of the liner, convectively grows along the liner, and regenerates sound near the downstream edge of the liner with a sound level higher than that incident sound level. It is shown that a homogenized approach, where the wall effect is described by a homogeneous impedance, can also explain the unstable behaviour above the liner. It reveals that a small wall resistance and a small and positive reactance are two necessary conditions for such an instability.
Type de document :
Article dans une revue
Liste complète des métadonnées

Littérature citée [46 références]  Voir  Masquer  Télécharger

https://hal.archives-ouvertes.fr/hal-02337036
Contributeur : Yves Aurégan <>
Soumis le : mardi 29 octobre 2019 - 11:34:22
Dernière modification le : jeudi 14 janvier 2021 - 15:04:18
Archivage à long terme le : : jeudi 30 janvier 2020 - 15:45:22

Fichier

jfm-InstabilityVF.pdf
Fichiers produits par l'(les) auteur(s)

Identifiants

Collections

Citation

Xiwen Dai, Yves Aurégan. A cavity-by-cavity description of the aeroacoustic instability over a liner with a grazing flow. Journal of Fluid Mechanics, Cambridge University Press (CUP), 2018, 852, pp.126-145. ⟨10.1017/jfm.2018.542⟩. ⟨hal-02337036⟩

Partager

Métriques

Consultations de la notice

85

Téléchargements de fichiers

193