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Contribution à l'étude de l'organisation d'un jet légèrement pulsé

Abstract : The present study is concerned with the experimental analysis of an axisymmetric water jet (Re ?10 [to the power] 4), free or slightly excited. The velocity measurements are realised with laser anemometer and/or hot film anemometer. In a first approaches, the study of the fields of average and fluctuation velocities allows the observation of a behaviour already met in literature. Our contribution is concerned with the supply of additional information regarding the formation and development of periodic structure by means of an exhaustive spectral and space-time analysis. Through spectral analysis of the fluctuations of longitudinal and radial velocities, it cornes forward sorne preferential radial distances which are distinct for each component. However, it seems that just at the outlet of the nozzle there is generation of two periodic structures, with characteristics related to the boundary layer thickness for the first, and to the jet diameter for the second. We note that pairing phenomena regards only the lastly designed structure. A slight pulsation of the jet, does not alter significantly the global behaviour of its development. However, in this case we observe only the generation of structures related to the pulsation frequency and to their successive pairing. Since this last phenomenon has the same characteristics as the one recorded for a free jet, the space-time analysis allows the tracking of the development of the structures and the proposition of a mechanism describing their origin development.
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Submitted on : Thursday, March 29, 2018 - 11:00:09 AM
Last modification on : Saturday, October 16, 2021 - 11:22:03 AM

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  • HAL Id : tel-01747444, version 1



Youcef Bahmed. Contribution à l'étude de l'organisation d'un jet légèrement pulsé. Autre [cond-mat.other]. Université Henri Poincaré - Nancy 1, 1997. Français. ⟨NNT : 1997NAN10036⟩. ⟨tel-01747444⟩



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