Free-stream turbulence effects on vortex-induced vibration and flow-induced force of an elastic cylinder

The effect of free-stream turbulence on vortex-induced vibration of an elastic cylinder in a cross-flow and the associated fluid forces was investigated experimentally. The range of Reynolds number investigated is 5000–41 000. A turbulence generation grid was used to generate turbulence intensity around 10% in the upstream flow. Cylinder displacements in the transverse direction at cylinder mid-span were measured in the reduced velocity range Ur0=1.45–12.08. The cylinder vibration has two dominant components, one at the frequency of vortex shedding and another at the natural frequency of the fluid-cylinder system. These are represented by their root-mean-square (r.m.s) values, wyV′ and wyM′, respectively. For a nonturbulent uniform flow, wyV′ is dominant in the Ur0 range of 1.45