Experimental investigation of in-line flow-induced vibration of a rotating circular?cylinder

摘要

This study experimentally investigates the in-line flow-induced vibration (FIV) of an elastically mounted circular cylinder under forced axial rotation in a free stream. The present experiments characterise the structural vibration, fluid forces and wake structure of the fluid–structure system at a low mass ratio (the ratio of the total mass to the displaced fluid mass) over a wide parameter space spanning the reduced velocity range $5leqslant U^{st }leqslant 32$ and the rotation rate range $0leqslant unicode[STIX]{x1D6FC}leqslant 3.5$ , where $U^{st }=U/(,f_{nw}D)$ and $unicode[STIX]{x1D6FC}=|unicode[STIX]{x1D6FA}|D/(2U)$ , with $U$ the free-stream velocity, $D$ the cylinder outer diameter, $f_{nw}$ the natural frequency of the system in quiescent water and $|unicode[STIX]{x1D6FA}|$ the angular velocity of the cylinder rotation. The corresponding Reynolds number (defined by $Re=UD/unicode[STIX]{x1D708}$ , with $unicode[STIX]{x1D708}$ the kinematic viscosity of the fluid) was varied over the interval $1349leqslant Releqslant 8624$ , where it is expected that the FIV response is likely to be relatively insensitive to the Reynolds number. The fluid–structure system was modelled using a low-friction air-bearing system in conjunction with a free-surface water-channel facility. Three vibration regions that exhibited vortex-induced vibration (VIV) synchronisation, rotation-induced galloping and desynchronised responses were observed. In both the VIV synchronisation and rotation-induced galloping?regions, significant cylinder vibration was found to be correlated with wake–body synchronisation within t