Numerical Study of Flow around a Rotating Disk with Different Radius

The flow induced by a rotating object in a vessel can be seen in fluid machinery such as centrifugal pumps and water turbines. This research focuses on the flow induced by rotating objects, especially the flow around the disk rotor in the vessel, and visualization experiments are being conducted. The following results were obtained by comparing the respective flow fields at different Reynolds numbers in a 3D visualization using Q-value. At r = 117 mm, when the vortex was well developed, two vortices were observed at both Reynolds numbers, although their visibility varied depending on the turbulence of the vortex. On the other hand, at r = 127 mm, two to four vortices were observed between Re = 3000 and 20,000. As the radius increases, the gap distance necessarily decreases. Therefore, the velocity gradient becomes larger. As the velocity gradient increases, turbulence is more likely to occur, and therefore, a variety of vortex structures may appear as in the case of r = 127 mm. It was found that the number of vortices may differ from region to region, as in the results for r = 127 and Re = 6000.