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ÉTUDE EXPÉRIMENTALE DE L'IDENTIFICATION DES SOURCES ACOUSTIQUES DANS LES JETS PAR L'ANALYSE DE LA FLUCTUATION DE PRESSION EN CHAMP PROCHE.

Abstract : This study was dedicated to the possibility of acoustic sources (coherent structures in particular) identification in jets turbulent mixing layer by using the Proper Orthogonal Decomposition (POD) applied to the near field pressure fluctuations. The first step consisted in measuring the pressure field close to a transonic jet and a supersonic jet. In both cases, the first two POD modes - which represent the major contribution to the spatial and spectral organization - presented features similar to those reported in the litterature. However, the only pressure field knowledge did not allow the physical interpretation of POD modes in terms of turbulent flow organization. Therefore a second experiment was carried out in a simpler configuration with a low exit speed jet. The longitudinal distribution of near field pressure fluctuations was measured simultaneously with the fluctuations of two velocity components in several normal sections. The spatial pressure-velocities correlations were then determined in the two-dimensional measurement field. Using these correlations and the longitudinal distribution of the pressure fluctuations, the large scale structures dynamics was estimated via the Linear Stochastic Estimate (LSE). This estimation of vortical field gave a reliable representation of the real large scale movements and was used to provide a physical interpretation of POD modes : the first four modes represent the organized part of the pressure field. Lastly, the far field acoustic radiation of the vortical estimation was evaluated and was found to be in conformity with what is expected.
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https://tel.archives-ouvertes.fr/tel-00133829
Contributor : Christophe Picard <>
Submitted on : Tuesday, February 27, 2007 - 9:03:07 PM
Last modification on : Monday, March 18, 2019 - 5:18:03 PM
Long-term archiving on: : Wednesday, April 7, 2010 - 1:03:33 AM

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  • HAL Id : tel-00133829, version 1

Citation

Christophe Picard. ÉTUDE EXPÉRIMENTALE DE L'IDENTIFICATION DES SOURCES ACOUSTIQUES DANS LES JETS PAR L'ANALYSE DE LA FLUCTUATION DE PRESSION EN CHAMP PROCHE.. Traitement du signal et de l'image [eess.SP]. Université de Poitiers, 2001. Français. ⟨tel-00133829⟩

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