Abstract
The existence of rotating instability region of the flow around a cylinder rotating between two stationary disks was founded in the previous research. In this paper, the peripheral velocity around the rotating cylinder in pipe was measured. In order to investigate the rotating instability, the flow of rotating cylinder in the pipe was calculated by the three dimensional numerical simulation. It was found that higher peripheral velocity region rotates with 12Hz frequency in both the experiments and the calculation. The vortices in the meridional plane between the rotating cylinder and the outer static wall was found.
