Radial Jet Reattaching on a Rotating Disk

Abstract

This study is concerned with the characteristics of a radial jet flow which reattaches on a coaxially rotating disk that the disk sets parallel to a cylindrical nozzle. The velocity fields near the disk surface and in the jet were measured by a hot-wire probe to clarify the variation of the basic characteristics of the flow. As the offset distance from the wall to the nozzle (step height) becomes high, the reattachment position moves to the upstream side depending on the disk rotating speed. The basic characteristics of the jet until it reattaches on the disk are similar to the radial free jet. In contrast, after the reattachment, they show the change similar to the radial wall jet without step height. Furthermore, the velocity in the reattaching region fluctuates periodically, and the frequency of the fluctuation decreases with the step height and increases with the disk rotating speed.