Abstract
In this study, we investigated experimentally the flow between two co-rotating disks with narrow spacings, enclosed by a stationary shroud at the circumference. By flow visualization with aluminium flakes in a water tank, indented shapes of the central core can be observed, and the flow can be classfied into six modes according to the core shapes. We developed a visualization technique with spherical perticles and irradiation of ultra-violet rays for observation of secondary flows. As spherical perticles, we use the bridged polystyrene perticles coated with luminous paint yellow. The equipment has a glass top. PIV analysis of visualizated photos reveals vortical structures in the secondary flow.
