STUDY OF FLOW AROUND A ROTATING CIRCULAR CYLINDER.

A flow field survey and aerodynamic force measurements were carried out on a rotating circular cylinder, which was placed perpendicular to the flow near the transition Reynolds number. Remarkable changes in the unsteady wake flow pattern were observed to occur at a particular rotational Reynolds number, which is based on the peripheral speed of the cylinder, with a corresponding abrupt reduction in the steady lift force. The characteristics of the wake vortices also showed substantial difference below and above the same rotation Reynolds number. And it is also made clear that the upper limit of the periodic vortex formation was observed to be governed by a non-dimensional peripheral speed, which is the ratio of the rotational Reynolds number to the ordinary Reynolds number.