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Analyse des écoulements inter-disques en vue d'optimiser les poussées axiales dans les machines hydrauliques utilisées en station hydro-électrique

Abstract : The properties of the turbulent flow confined in a cavity delimited by two parallel coaxial disks, one of which is in rotation, are very sensitive to the peripheral geometry of the system. Recent studies have shown that the solid body rotation flow predicted by the theory of Batchelor is not systematically observed when the cavity is isolated, i.e. without superimposed flow. The objective of this thesis is to better understand this phenomenon and extend the study to the case of the cavity with superimposed centripetal inflow. The first part of the work handles with the theoretical aspects of the problem. A first conservation of mass of exchange of fluid is made from stationary solutions of the flow in the boundary layers, developed by von Kármán and Bödewadt. These solutions are coupled with new hypotheses to take account of circulation of flow outside the boundary layers and the rate of pre-swirl velocity. We obtain analytical solutions for the radial distributions of swirl ratio in the central core, of the static pressure on the stationary wall and of total pressure at the mid-high of the cavity, for the both cases with or without superposed radial inflow. The second part is dedicated to the experimental and numerical "tools" needed to validate these theoretical solutions. This chapter includes firstly the description of the experimental setup, techniques of measurements, and the program of case studied in the framework of this thesis. Numerical simulations are performed using the industrial computing code FLUENT. Details regarding the choice of computational domain, grid mesh, boundary conditions and turbulence model used are provided secondly. The validation of theoretical solutions is the subject of the last two chapters, devoted respectively to the cases of isolated cavities and of systems with superposed centripetal radial inflow. The agreement between the experiment, the numerical results and theory is generally very good, what comforts us on choosing the basic assumptions. The analysis of the results leads in particularly to understand the mechanism of apparition of the solid body rotation flow provided by Batchelor. However, the use of models is not universal because it requires adjustment of constants, for which we are trying to identify the most general empirical relationships possible.
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https://pastel.archives-ouvertes.fr/pastel-00545605
Contributor : Fadi Abdel Nour <>
Submitted on : Friday, December 10, 2010 - 5:22:45 PM
Last modification on : Thursday, February 21, 2019 - 10:33:56 AM
Long-term archiving on: : Friday, March 11, 2011 - 4:06:42 AM

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  • HAL Id : pastel-00545605, version 1

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Fadi Abdel Nour. Analyse des écoulements inter-disques en vue d'optimiser les poussées axiales dans les machines hydrauliques utilisées en station hydro-électrique. Mécanique des fluides [physics.class-ph]. Arts et Métiers ParisTech, 2010. Français. ⟨NNT : 2010ENAM0044⟩. ⟨pastel-00545605⟩

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