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Vers une mesure du vent thermoacoustique

Abstract : The non-linear phenomena which appear in thermoacoustic systems generate continuous secondary flows, superposed to the dominant acoustic oscillations, reducing the systems efficiency. The aim of this study is to characterize the acoustic field created by a thermoacoustic wave generator and to highlight the secondary flows. We measure the velocity field with a Particle Image Velocimetry method (PIV). The first measurements, disordered with respect to the acoustic period, allow the reconstruction of the acoustic field by the way of a projection technique using singular values decomposition (SVD). This method is part of a data processing group which is able to obtain results agreeing with linear acoustic theory. They highlight an important harmonic content and the non-linear property of the acoustic flow. The estimation of the mean velocity over the time period indicates the existence of a continuous flow different of Rayleigh-Schlichting streaming. In the measurements window, this flow consists in convection vortices; their height tends to grow with the drive-ratio. The continuous flow shows a tri-dimensional behaviour. A second type of PIV measurements synchronized with the pressure signal gives complementary information about streaming flows and globally confirms the obtained results from the first measurements. Nevertheless, these synchronised measurements are less precise than the first.
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https://tel.archives-ouvertes.fr/tel-00445461
Contributor : Philippe Debesse <>
Submitted on : Wednesday, December 15, 2010 - 2:37:28 PM
Last modification on : Thursday, December 10, 2020 - 12:31:17 PM

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  • HAL Id : tel-00445461, version 2

Citation

Philippe Debesse. Vers une mesure du vent thermoacoustique. Acoustique [physics.class-ph]. Université Pierre et Marie Curie - Paris VI, 2008. Français. ⟨tel-00445461v2⟩

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