结构与尾流非线性耦合涡激振动预测模型

预测圆柱涡激振动的尾流振子模型中,通常采用线性的耦合模型,例如位移或者速度、加速度耦合来表征结构对尾流的作用。三种线性模型在预测圆柱锁频阶段的动力特性时存在差异,而且适用范围也受质量比的限制。提出了考虑结构与尾流动力非线性耦合的模型,该模型基于加速度耦合并结合速度耦合进行修正,适用范围不受质量比的影响;与实验结果的对比表明该模型可以更合理地给出锁频区域以及结构位移响应和尾流升力。最后,利用新模型讨论了质量比对锁频阶段结构振动幅值、尾流升力及频率比的影响;结果表明,随着质量比的增大,结构锁频区域变窄,结构振幅和尾流升力幅值减小。

Prediction of vortex-induced vibration of cylinder based on the nonlinear coupling of structure and wake oscillator

In the prediction of cylinder vortex induced vibration (VIV) using the wake oscillator model, the action of the structure on the fluid wake oscillator is commonly modeled by linear models such as linear displacement, velocity and acceleration coupling. However, these linearly coupling models often present different dynamical behaviors during the lock in, and are suitable to different ranges of mass ratio of cylinder. An alternative nonlinear coupling model, combining a velocity coupling with an acceleration coupling term, is proposed in this study. The comparison of the proposed model with experimental data indicates that the model is capable of presenting a more reasonable dynamical behavior in lock-in and suitable for a wider range of mass ratio. Further, the influences of mass ratio on the structural vibration amplitude, wake lift and frequency ratio are explored. It is found that with the increase of mass ratio, the structural amplitude and wake lift decrease, and meanwhile the range of lock-in gets narrower.