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Etude statistique du champ de pression à proximité des jets axisymétriques turbulents à haut nombre de Reynolds

Abstract : The jet near field is a region where hydrodynamic and acoustic pressure contributions coexist. Theirs characteristics are unidentified, leading to a controversial definition of the borders of this zone and the impossibility to predict the measured pressure levels. This zone is of strong interest in the study of the jet dynamic and for the role coherent structures can play in the aeroacoustic sound generation mechanisms. The present study involves a subsonic jet, Mach number Mj=0.3, and a supersonic jet, Mj=1.4. The results presented are based on near and far-field acoustic measurements, and on near-field pressure measurements synchronized with Laser Doppler Velocimetry (LDV) flow measurements. A strong interaction between both pressure contributions is brought to light with loss of coherence levels. This phenomenon, of which a model is proposed, allow to define precisely the near field border by the product of the wave number and the radial location kr=1.3. The analysis using proper orthogonal decomposition (POD), which a proposed data normalisation method is based on, point out the very coherent character of the near field pressure at low frequencies as well as the importance of considering its azimuthal contributions. A separation of the hydrodynamic and acoustic pressure contributions is obtained by a POD filtering. The instantaneous pressure field is determined on a surface surrounding the jet by a spectral extension of the linear stochastic estimation (LSE). These results are used to estimate the acoustic radiation from the jet using a Kirchhoff's integral formulation and also to extract the tridimensional organization of the flow.
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Contributor : Francois Coiffet <>
Submitted on : Wednesday, May 2, 2007 - 7:50:55 PM
Last modification on : Monday, March 18, 2019 - 5:18:03 PM
Long-term archiving on: : Friday, September 21, 2012 - 2:30:10 PM


  • HAL Id : tel-00144345, version 1



Francois Coiffet. Etude statistique du champ de pression à proximité des jets axisymétriques turbulents à haut nombre de Reynolds. Acoustique [physics.class-ph]. Université de Poitiers, 2006. Français. ⟨tel-00144345⟩



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