Effect of the random component in the vortex-induced vibration

In this paper, vortex-induced vibration of a circular cylinder supported by cantilever beams under a uniform air flow is studied, and random component of them is considered to improve the model of vortex-induced vibration. A cylinder is supported by a pair of elastic cantilever beams and placed in front of a wind tunnel. Experiments are conducted in wide range of flow speed to investigate the property of the vibration. Flow speed is changed by two ways, which are increase direction and decrease direction, to investigate the hysteresis property of the vortex-induced vibration. Time-historical responses of the vortex-induced vibration are measured experimentally. Then, the time-frequency analysis is applied to the signal, so characteristics of the nonlinear coupled vibration between fluid and structure are clearly observed. Numerical simulations are also conducted using a wake oscillator model with acceleration coupling and random components. By comparing the results of ordinal model and proposed model which considers random components, an advantage of the proposed model is shown. Simulation results agree with the experimental results better than the results of the simulation with ordinal model.