Vibration of a Cylinder Caused by Wake Force

Abstract

In this report experimental results on the vibration of a cylinder caused by shedding vortices are presented. The experiments were undertaken at larger Reynolds number than in author's previous report. There are two experiments in this study, one being on an elastically supported cylinder and the other on a crank-excited cylinder. In the former, the exciting force coefficient is determined from a decrement and an amplitude of the cylinder. In the latter, the exciting force coefficient is found by an integration of pressures on the cylinder surface. These two results coincide with each other ; the exciting force suddenly decreases at nearly the critical Reynolds number. Moreover, at sub-critical Reynolds number a self-exciting force is induced just as in authors' previous report, but at super-critical Reynolds number the exciting force decreases with an increasing cylinder amplitude and at too large an amplitude the force is changed to a damping force.