Abstract
This work presents influence of flow in the narrow space between a pair of coaxially rotating disk enclosed by a fixed outer wall, viz., a an outer shroud. The flow consists of two different parts; one is referred to as the 'central core,' and the other the 'secondary flow.' The former is the flow in solid-body motion at the central area. The later is the flow with vortical structures developed by share stress on the outer wall. The boundary between those flows tends to have polygonal shapes. The number of vortical structures in the secondary flow, i.e., the number of apices of the polygon, depends on the Reynolds number Re, and the ratio δ of the disk gap to the disk radius and the ratio of wall radius to disk radius λ. We study the flow using UVP(Ultrasonic Velocity Profile).
