Flow Behavior around Cone Rotating in Stationary Outer Cylinder

Flow behavior around a cone rotating in a coaxial outer cylinder at rest has been observed by flow visualization technique. Under the rotational speed of the cone, flow is laminar circulation in one part of a working space, and a Taylor vortex is formed in the other part. Such stable coexistence of different flow regimes in a working space induces peculiar phenomena in flow behavior. According to the flow behavior observed, seven distinct kinds of flow regimes have been identified and the corresponding regions are shown in the flow diagram, of which coordinates are Reynolds number defined by the angular velocity of cone and the radius of outer cylinder as the representative quantities, and the relative radius defined by the ratio of local radius of cone to that of outer cylinder. The typical flow regimes are as follows : I. laminar circulation; II. laminar Taylor vortex with interface travelling towards the laminar region I in which a penetrating vortex is viscous dissipated; III. Taylor vortex with stationary interface and with hysteresis effect on the number of vortices in working space; IV. turbulent Taylor vortex with deformed interface travelling towards the most dissipative region; V. spiral turbulence rushing towards the fully turbulent region VII; VI. unstable flow of which the regime cannot definitely be characterized; VII. fully turbulent flow. The criteria of Taylor transition in the case of a rotating cone are defined by the local value at the boundary of regions I and II, and coincident with the critical Taylor number to the rotating inner cylinder. In the region II mentioned above, the shift of vortex interface is represented by the equation which is similar to a Lagrangian expression of effluent flow from a point source in a two-dimensional field, being independent of Re and cone geometry in the generalized coordinate. Furthermore, the phase shift of the right-and left-hand vortices has been measured and phenomenologically correlated with the specified values in the generalized coordinate. Based on this correlation, the size of vortex depending on location and Re has been estimated and compared with the measurements. The torque of rotating cone and inner cylinders hasb een directly measured. Assuming the local cylinder approximation for a cone, the torque of the cone has been estimated from the correlation to the cylinder. The estimations agree with the measurements.