Étude de l'écoulement entre deux cylindres coaxiaux à entrefer constant et à entrefer ondule par la surface du cylindre intérieur tournant

Abstract : This report presents the investigations of a flow confined between two coaxial cylinders. The outer cylinder is smooth while inner cylinder may be either smooth or may have axially symmetric wavy surface. The study concerns the classical Couette flow and the flow forced by geometric waves of two wavelengths and several amplitudes. In the later configuration, the basic flow, even at very small Taylor numbers, is three-dimensional for which a modeling approach, using the geometric perturbation concept, is suggested. Using the techniques like, PIV and Electrochemical Shear Stress, velocity fields in an axial plan and local wall shear velocity gradients, as a function of Taylor number and for different geometries, are given. From these results, the average and spectral evolutions, numerical and experimental velocity fields are analyzed for all geometries. A fine step variation of Taylor number has allowed to make evident on one hand, a frequency/amplitude shift in wavy, vortex flow in the case of the classical Couette flow and on the ether, a variety of bi-cellular or multi-cellular modes per wavelength as a function of geometric wavelength and amplitude. These investigations have also allowed showing that in the case of small wavelength, the bi-cellular mode persists at high Taylor numbers, and is accompanied by vortices size asymmetry. In the geometries studied, the flow destabilizes beyond an experimentally determined critical Taylor number.
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Theses
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http://docnum.univ-lorraine.fr/prive/INPL_T_1999_RAFIQUE_M.pdf
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https://hal.univ-lorraine.fr/tel-01750633
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Submitted on : Thursday, March 29, 2018 - 12:51:02 PM
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Mohammad Rafique. Étude de l'écoulement entre deux cylindres coaxiaux à entrefer constant et à entrefer ondule par la surface du cylindre intérieur tournant. Autre. Institut National Polytechnique de Lorraine, 1999. Français. ⟨NNT : 1999INPL107N⟩. ⟨tel-01750633⟩

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