EXPERIMENTAL INVESTIGATION OF THE FREE SURFACE EFFECT ON THE CONICAL TAYLOR-COUETTE FLOW SYSTEM

Abstract

The aim of this work is to highlight the critical thresholds corresponding to the onset of different instabilities considered in the flow between two vertical coaxial cones with and without free surface. The inner cone is rotating and the outer one is maintained at rest. Both cones have the same apex angle Phi = 12 giving a constant annular gap delta = d/R-1max. The height of the fluid column is H = 155mm and can be progressively decreased for each studied case of the flow system. Two kinds of configuration are studied, small and large gap configurations The working fluid is assumed as Newtonian and having constant properties as density and viscosity within the range of the required experimental conditions. By means of visualization technique of the flow we were able to show the different transition modes occurring in the conical flow system according to the aspect ratio and then the induced action of the free surface which introduces a delay in the onset of different instability modes. The obtained results in term of features and stability of the flow are compared to those of M. Wimmer [3-8] and N Noui-Mehidi [9].