圆柱涡激振动的结构-尾流振子耦合模型研究

建立了一个新的结构-尾流振子耦合模型. 流场近尾迹动力学特征被模化为非线性阻尼振子，采用van der Pol方程描述. 以控制体中结构与近尾迹流体间受力互为反作用关系来实现流固耦合. 采用该模型进行了二维结构涡激振动计算，得到了合理的振幅随来流流速的变化规律和共振幅值，并正确地预计了共振振幅值$A_{\max}^\ast$随着质量阻尼参数$\left( {m^\ast + C_A } \right)\zeta$的变化规律，给出了预测$A_{\max }^\ast$值的拟合公式. 采用该模型计算了三维柔性结构在均匀来流和简谐波形来流作用下的VIV响应. 结构在均匀来流作用下振动呈现由驻波向行波的变化过程, 并最后稳定为行波振动形态.在简谐波形来流作用下，结构呈现混合振动形态，幅值随时间呈周期变化. 

THE STUDY OF VORTEX-INDUCED VIBRATIONS BY COMPUTATION USING COUPLING MODEL OF STRUCTURE AND WAKE OSCILLATOR

A new model of coupling structure and wake oscillator invortex-induced vibration (VIV) is established. It is based on forcebalance between structure and near wake flow. The nonlinear near wakevortex dynamics is modeled by a nonlinear oscillator satisfied the Van derpol equation. According to the study of 2-DVIV, the coupling model describes the featuresof response versus reduced velocity qualitatively and quantitatively. These results prove that the peak amplitude of structure$A_{\max }^\ast $ decreases as the mass-damping $(m^\ast + C_A )\zeta $increases. An empirical formula on $A_{\max }^\ast $ versus $(m^\ast + C_A)\zeta $ is obtained based on these results. The present 3-D coupling modelis employed in the study of 3-D VIV of flexible slender cylinder. Dynamicresponse behavior of uniform flow presents a change from standing wave totraveling wave. Under non-uniform flow whose profile is sinusoidal, thestructure vibration is a combination of standing and traveling waves alongthe span. These results are similar with those from direct numericalsimulation (DNS), and some other previous results.