2D-PTV MEASUREMENT OF EXPANDING CONCENTRIC ANNULAR FLOW WITH A ROTATING INNER WALL

摘要

The turbulent flow field in an expanding concentric annular flow passage with a rotating inner wall was measured by using 2-Dimensional Particle Tracking Velocimetry (2D-PTV). In this study, two different shapes, concave and convex types, were examined in rotating condition. The inlet through-flow Reynolds number based on the twice height of the flow passage and the mean flow velocity was set at a constant value of 1000. The Taylor number based on the inner wall radius of 45°. location from the origin and the angular velocity of the inner wall was set at a constant value of 0 and 4000. In all cases, flow separation occurred in the inlet region, which was caused by flow inertia. Furthermore, in the rotating concave passage, the flow separation area reached the downstream region, and a high-speed flow along the inner wall occurred for centrifugal force of the rotating inner wall. As a result, due to a high-speed flow along the inner wall, reverse flow from the exit part of the outer wall side occurred, which could be understood by mass conservation. In the both rotating flow passages, the turbulent kinetic energy of the visualized plane in the downstream region was increased by the shear stress due to the rotating inner wall and the centrifugal force.