Visualizations of the transitional flow patterns at the mid-span between shrouded co-rotating disks

Transitional air flow patterns at the mid-plane of gap between co-rotating disks in a stationary cylindrical enclosure are visualized under the acceleration condition of disks. The flow visualization is performed using olive oil particles with a laser sheet and CCD camera. On disk spinning-up, the transition flow patterns are clearly observed. The affect of magnitude of acceleration on the onset of transition and the relations of the number of vortex cells in fully turbulent regime of the flow in an outer region of the flow field to the rotating speed are also investigated. The centrifugal effect of particle is evaluated from the comparison with visualization results using hollow glass spheres.