行波壁抑制圆柱涡激振动的数值模拟研究

采用CFD数值模拟方法完成了圆柱绕流-涡激振动-行波壁流动控制全过程的数值模拟,重点研究行波壁流动控制方法对低雷诺数下两自由度弹性支撑单圆柱涡激振动的抑制作用。详细分析各阶段圆柱横向和流向位移、质心运动轨迹、升力和阻力系数等随频率比的变化。结果表明:行波壁圆柱的波谷处可以产生一系列稳定的随行波壁运动的小尺度旋涡,有效抑制圆柱表面分离涡的产生,达到消除圆柱绕流尾迹和抑制涡激振动的目的;在计算初始和中途启动的行波壁流动控制方法显著抑制了圆柱横向和流向振动、降低了圆柱升力系数脉动值和阻力系数均值,但阻力系数脉动值则明显增大。

NUMERICAL SIMULATION OF SUPPRESSING VORTEX-INDUCED VIBRATION OF AN ELASTICALLY MOUNTED CYLINDER BY TRAVELLING WAVE WALL

The CFD numerical method was employed to simulate the whole process starting from the flow around a fixed cylinder, then to a oscillating cylinder (vortex-induced vibration, VIV) and finally to the oscillating cylinder (VIV) controlled by using a travelling wave wall method. The study mainly focused on using the travelling wave control method to suppressing the VIV of an elastically mounted cylinder with two degrees of freedom at low Reynolds numbers. The cross flow (CF) and inline flow (IL) displacements, the centroid motion trajectories and the lift and drag forces of the cylinder changing with the frequency ratios were analyzed in detail. The results indicate that a series of small scale vortices will be formed in the troughs of the travelling wave wall located on the rear part of the cylinder, and they can effectively control the flow separation from the cylinder surface and then result in eliminating the oscillating wake and suppressing the VIV of the cylinder. The travelling wave whatever starting from the initial time or a some halfway can dramatically suppress the CF and IL vibrations of the cylinder and can significantly decrease the fluctuations of the lift coefficients and the average values of drag coefficients. However, it will simultaneously dramatically increase the fluctuations of drag coefficients.