高雷诺数下水翼涡发放频率预报方法

  目的  为了实现亚临界雷诺数下圆柱涡激振动振幅响应的准确预报，利用数值模拟方法研究强迫振动时圆柱的升力系数与振幅比（Cl-A/D）之间的关系。  方法  基于Realizable k-ε 湍流模型，采用有限体积法对圆柱的强迫振动进行二维数值模拟，计算得到激振频率比f_e/f_n=1附近范围内不同振幅比下的升力系数曲线。选取圆柱振动速度最大时对应的升力系数，建立Cl-A/D关系曲线。  结果  结果表明，Cl-A/D拟合曲线总体变化趋势与涡激振动预报程序SHEAR7的结果吻合良好。
同时，各激振频率比f_e/f_n下的零升力系数点均位于振幅比A/D=0.8附近，且结构尾涡脱落模式在A/D=0.8附近发生了转变，由“P+S”模式转变到“2P”模式（P 表示一对旋转方向相反的旋涡脱落，S 表示单个旋涡脱落）。在圆柱涡激振动实验中，发现涡激振动出现“锁定”时的最大振幅在0.8D附近。  结论  亚临界雷诺数下强迫振动圆柱Cl-A/D关系曲线升力系数为零时对应的振幅比与圆柱在涡激振动中的最大响应振幅比基本保持一致，且圆柱尾涡脱落模式在此振幅比下发生了转变。

Vortex-induced vibrations

  Objective  In order to achieve the accurate prediction of the amplitude response of a vortex-induced vibrating cylinder under the sub-critical Reynolds number, a method for establishing a Cl-A/D (lift coefficient-amplitude ratio)model of the forced vibration of the cylinder by numerical simulation is proposed.  Methods  Based on the Realizable k-ε model, a two-dimensional numerical simulation of the forced vibration of a cylinder is carried out using the finite volume method. The calculated lift coefficient curves under different amplitude ratios A/D in the range of excitation frequency ratio f_e/f_n=1 are obtained.
The lift coefficient corresponding to the maximum vibration velocity of the cylinder is then selected to establish the Cl-A/D model.   Results  The results show that the overall trend of the Cl-A/D fitting curve is in good agreement with the predicted results of SHEAR7. At the same time, it is found that the