Experimental study of vortex induced vibration of an elastically mounted sphere in a pipe

In this work, we study the response of an elastically-mounted sphere in a pipe to the flow of a fluid in the pipe. The fluid passes through the gap between the pipe wall and the sphere's surface, displacing the sphere. As a result the sphere can move with two degrees of freedom in the radial direction of the pipe. In this paper, experiments are described in which we observe the rotation of the sphere around the longitudinal axis of the pipe. This rotation is induced by vortex shedding from the sphere. We will discuss experimental investigations of this strong sphere rotation, the interaction of forces between pipe and sphere, and a strategy for such analyses.