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Développement de méthodes de séparation des nombres d'onde acoustiques et convectifs en écoulements turbulents pariétaux

Abstract : This study aims at the development of techniques of separation of the acoustic and aerodynamic contributions of wall-pressure fluctuation fields under turbulent flows. These techniques of wavenumber separation use the spatial properties of these fluctuations. The understanding of the phenomena of each of the two kinds of wall-pressure fluctuations loading the side window of a vehicle comes to serve an industrial stake in reduction of the noise level inside the cabin due to the shape of car. Experiments in an anechoic wind-tunnel are led to obtain measures of wall-pressure fluctuations for several kinds of flows. Thus a turbulent boundary layer flow fully developed on a flat plate, detached flows downstream to three geometries of forward facing steps, as well as downstream to the A-pillar on real vehicle are considered. A representation of wavenumber-frequency spectra (obtained by the spatial correlogram method) is chosen to separate both contributions. This technique applying only to stationary and homogeneous flows, new techniques based on the Empirical Mode Decomposition (EMD) are used in order, on one hand to improve the separation of both contributions (using the spatial EMD), on the other hand to obtain a multi-scale decomposition in time (using the Ensemble-EMD). Thanks to these methods, a more precise observation of the convected and acoustic phenomena on the wall is proposed.
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https://tel.archives-ouvertes.fr/tel-00693903
Contributor : Sébastien Debert <>
Submitted on : Thursday, May 3, 2012 - 9:18:27 AM
Last modification on : Monday, March 18, 2019 - 5:18:04 PM
Long-term archiving on: : Saturday, August 4, 2012 - 2:25:11 AM

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  • HAL Id : tel-00693903, version 1

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Sébastien Debert. Développement de méthodes de séparation des nombres d'onde acoustiques et convectifs en écoulements turbulents pariétaux. Acoustique [physics.class-ph]. Université de Poitiers; Ecole Supérieure d'Ingénieurs de Poitiers - ESIP, 2008. Français. ⟨tel-00693903⟩

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