Numerical simulation of acoustic propagation in a turbulent channel flow with an acoustic liner
| Autor: | Sebastian, Robin |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
Acoustique en conduite
Impédance acoustique Écoulement de canal turbulent Instabilité Simulation des grandes échelles Calcul haute performance Acoustic liner Duct acoustics Channel flow Wall turbulence Large-Scale motions Compressibility Instability Drag Implicit Large Eddy Simulation (ILES) High performance computing 620.2 |
| Druh dokumentu: | Obrázek |
| Popis: | Les matériaux absorbants acoustiques, qui sont d’un intérêt stratégique en aéronautique pour la diminution passive du bruit des réacteurs d’avion, conduisent à une physique complexe où l’écoulement turbulent, des ondes acoustiques, et l’absorbant interagissent. Cette thèse porte sur la simulation de cette interaction dans le problème modèle d’un écoulement de canal turbulent avec des parois impédantes, par le biais de simulations numériques aux grandes échelles implicites, dans un contexte de calcul haute performance.Une étude est d’abord faite des grandes échelles dans un canal turbulent avec des parois rigides, en s’intéressant plus particulièrement à l’effet d’une faible compressibilité (Mach Acoustic liners are a key technology in aeronautics for the passive reduction of the noise generated by aircraft engines. They are employed in a complex flow scenario in which the acoustic waves, the turbulent flow, and the acoustic liner are interacting.During this thesis, in a context of high performance computing, a compressible Navier-Stokes solver has been developed to perform implicit large eddy simulations of a model problem of this interaction: a turbulent plane channel flow with one wall modeled as an impedance condition.As a preliminary step the wall-turbulence in rigid channel flows and associated large-scale motions are investigated. A straightforward algorithm to detect these flow features is developed and the effect of compressibility on the flow structures and their contribution to the drag are studied. Then, the interaction between the acoustic liner and turbulent flow is investigated assuming periodicity in the streamwise direction. It is shown that low resistance and low resonance frequency tend to trigger flow instability, which modifies the conventional wall-turbulence and also results in drag increase.Finally, the simulation of a spatial channel flow was addressed. In this case no periodicity is assumed and an acoustic wave can be injected at the inlet of the domain. The effect of turbulence on sound attenuation is studied without liner, before a liner is introduced on a part of the channel bottom wall. In this more realistic case, it is confirmed that low resistance acoustic liners trigger an instability at the leading edge of the liner, resulting in drag increase and excess noise generation. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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