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Numerical analysis of the linear and nonlinear vortex-sound interaction in a T-junction

Bauerheim, Michaël and Boujo, Edouard and Noiray, Nicolas Numerical analysis of the linear and nonlinear vortex-sound interaction in a T-junction. (2020) In: AIAA AVIATION FORUM, 15 June 2020 - 19 June 2020 (Virtual Event, United States).

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Official URL: https://doi.org/10.2514/6.2020-2569

Abstract

T-junctions correspond to a classical academic configuration employed to unravel the vortexsound interaction leading to self-sustained oscillations. It is composed of a closed deep cavity exposed to a low-Mach grazing flow, in which an unstable shear layer can develop. Many studies usually consider this hydrodynamic instability either as a “flapping shear layer", or as a “discrete vortex shedding", which then couples with the acoustic field. This paper follows the idea that these two descriptions are related to the linear and non-linear regimes of the shear layer response to acoustic waves, and thus intends to further analyze these regimes and their transition. To do so, a typical T-junction turbulent flow is computed by forced Large Eddy Simulation (LES) where acoustic waves are injected at several amplitudes. The flow response is extracted, and exhibits a linear regime as well as two distinct non-linear regimes where a partial saturation of the response occurs. The post-processing of the flow field in the three situations reveals that a flapping mechanism exists at low wave amplitudes, whereas a vortex shedding appears for highest acoustic levels. For moderate wave amplitudes, the behavior of the shear layer lies between these two classical views. This suggests that during self-sustained oscillations, a transition between these scenarios occurs, starting from a flapping motion followed by a vortex shedding.

Item Type:Conference or Workshop Item (Paper)
HAL Id:hal-02923535
Audience (conference):International conference proceedings
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut Supérieur de l'Aéronautique et de l'Espace - ISAE-SUPAERO (FRANCE)
Other partners > Ecole Polytechnique (FRANCE)
Other partners > Eidgenössische Technische Hochschule Zürich - ETHZ (SWITZERLAND)
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Deposited On:27 Aug 2020 09:10

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