The Effect of Flange Type End Plates on the Flow Around a Circular Cylinder : The Peculiar Phenomenon for the Small Distance Between Two End Plates

The effect of the end plates, which are often used to reduce the infuluence of side-wall boundary layer on the flow field around a circular cylinder normal to the flow, has been studied experimentally. Both the distance between two end plates and the diameter of flange type end plates are alterd for the measurements of surface pressure distribution and wake velocity profile. Flow visualization with smoke-wire technique is also carried out to make clear the flow pattern around a circular cylinder. It was found that the drag coefficient decreased drastically with a sudden increase the base pressure coefficient when the distance between two end plates becomes smaller than the critical value. So this state was regarded as a peculiar phenomenon. In this peculiar phenomenon, both the velocity defect and the turbulent intensity in the wake showed the large value. It was also observed that the flow field around the cylinder was definitely three-dimensional.