Modélisation de la réponse vibro-acoustique d'une structure excitée par une couche limite turbulente en présence d'un gradient de pression statique

Abstract : The aim of this thesis is to develop a numerical method to predict the acoustic radiation, either in a light or in a heavy fluid, from a structure excited by a Turbulent Boundary Layer (TBL), in the presence of a pressure gradient. The proposed methodology consists in three steps: the characterization of the mean flow from a steady-state RANS calculation, the modeling of the wall-pressure fluctuations from semi-empirical models, and the vibro-acoustic calculation in response to fluctuating pressure. In this study, a particular attention is given to the effects of a pressure gradient in the mean flow, which occurs in most of the industrial applications. To analyze those effects, we first propose a study of a flow case with negative and positive pressure gradient, which corresponds to previous measurements in a wind tunnel. This validation step highlights the significance of taking into account the pressure gradient in the global modeling. To estimate the vibro-acoustic response of the TBL-excited structure in the low and mid frequency band, a difficulty lies in the coupling between the deterministic vibro-acoustic model and the statistical wall-pressure model. Several approaches are studied to inject the hydrodynamic excitation in the vibro-acoustic model: a) by considering a spatially allocated excitation; b) by modeling the excitation with a plane wave field; c) by using a reciprocity principle; d) by using samples of uncorrelated plane waves. These approaches are tested on a heavy fluid test case which permits to study the influence of calculations parameters and to discuss the advantages and disadvantages of each method. The vibro-acoustic calculations are performed with the PTF approach (Patch Transfer Functions), which allows taking into account the heavy fluid-structure coupling without increasing time computation. Moreover in order to treat the high frequency range using SEA method (Statistical Energy Analysis), theoretical developments are proposed with simplifying assumptions to estimate the injected power to the structure from the expression of the wall-pressure fluctuations in the wavenumber domain. A last part is dedicated to the extension of these vibro-acoustic methods in order to take into account the spatial evolution of the TBL in the presence of a pressure gradient. The formalism relies on a decomposition of the structure into zones on which different wall-pressure cross-spectra are applied. This approach is applied on an industrial test case of a turbulent flow on a submarine sail profile. The influence of the hypothesis necessary to the decomposition is first studied with a homogeneous excitation. The interest to take into account the spatial evolution of the TBL in the radiated pressure can then be highlighted in this case.
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https://tel.archives-ouvertes.fr/tel-01570243
Contributor : Marion Berton <>
Submitted on : Friday, July 28, 2017 - 4:30:13 PM
Last modification on : Friday, October 26, 2018 - 10:35:12 AM

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  • HAL Id : tel-01570243, version 1

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Marion Berton. Modélisation de la réponse vibro-acoustique d'une structure excitée par une couche limite turbulente en présence d'un gradient de pression statique. Mécanique [physics]. Ecole Centrale de Lyon, 2014. Français. ⟨tel-01570243⟩

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