CIRCULAR COUETTE-FLOW WITH PRESSURE-DRIVEN AXIAL-FLOW AND A POROUS INNER CYLINDER

In a rotating filter separator a suspension is introduced at one end o f the annulus between a rotating porous inner cylinder and a fixed imp ermeable outer cylinder. The filtrate is removed through the inner cyl inder and the concentrate is removed from the opposite end of the annu lus.from which the suspension entered. The flow in a rotating filter s eparator is circular Couette flow with a pressure-driven axial flow an d a suction boundary condition at the inner cylinder. Flow visualizati on was used to determine the effect of the Taylor number, axial Reynol ds number, and radial Reynolds number on the types of flows present in the annulus. A rich variety of secondary vortical flows appear, depen ding upon the flow parameters. The radial inflow at the inner cylinder delays the appearance of supercritical circular Couette flow and prev ents the appearance of certain flow regimes that have a helical vortex structure. Nevertheless, the average azimuthal velocity measured usin g laser Doppler velocimetry indicates that the velocity profile is nea rly the same for all supercritical flow regimes.