基于离散点涡的双自由度涡激振动尾流振子模型研究

建立了一种新的预报双自由度圆柱涡激振动响应的尾流振子模型,提出了以近壁点涡强度为变量描述尾流振子方程.通过势流理论推导出了结构所受流体流向和横向水动力与点涡强度的量化关系,从而得到了结构振子和流体振子的耦合方程组.使用该模型对圆柱的双自由度涡激振动问题进行了数值计算,得到了结构流向和横向的响应振幅及频率的变化规律.通过与实验结果进行对比,表明模型预测的涡激共振区、锁定频率和“8”字形运动轨迹等结果与实验观测结果基本一致.

RESEARCH ON WAKE-OSCILLATOR MODEL IN 2-DOF VORTEX-INDUCED VIBRATION OF CYLINDER BASED ON DISCRETE POINT VORTEX

A new wake-oscillator model is presented to predict the response of vortex-induced vibration of a solid cylinder of two degrees of freedom. The strength of a near-wake discrete point vortex is put forward to represent the state variable of the wake oscillator. Based on potential flow theory, the relationship between in-line (IL) or cross-flow (CF) fluid forces on a structure and the vortex strength is quantified, which leads to establish a coupled fluid-structure equation. The model is solved by the numerical method and then the IL or CF amplitude and frequency are obtained. A comparison to the existing experimental results shows that the features of the synchronization domain, lock-in frequency and figure-of-eight trajectory are consistent with the experimental measurements.