Numerical simulation of vortex-induced vibration of two circular cylinders of different diameters at low Reynolds number
Numerical simulation of vortex-induced vibration of two circular cylinders of different diameters at low Reynolds number
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DOI：
10.1063/1.4816637
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发表时间：
2013-08
影响因子：
4.6
通讯作者：
Ming Zhao;G. Yan
中科院分区：
文献类型：
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作者：
Ming Zhao;G. Yan
对低雷诺数（250）下两个刚性耦合的不同直径圆柱的两自由度涡激振动进行了数值研究。在直径比和质量比保持不变的情况下，重点研究了小圆柱位置角对涡激振动锁定区的影响。对小圆柱的位置角α在0° ~ 180°范围内以22.5°为间隔，折合速度在1 ~ 15 °范围内以1为增量进行了仿真。为了找出两个圆柱之间的差距对振动的影响，考虑了两个间隙直径比（0和0.2）。结果表明，与单圆柱情况相比，当小圆柱位置角为0°、22.5°、90°和112.5°时，约化速度的锁定区明显加宽。在G = 0和α = 90°时，观察到以规则或不规则间隔的高振幅扰动为特征的规则振动的脉冲拍现象。在α = 135°时，在计算的两种间隙（G = 0和0.2）的约化速度范围内观察到不止一个锁定区。在两个气缸之间设置小间隙（间隙直径比为0.2），通过缩小锁定范围和降低振动幅度来减轻振动。
Two-degree-of-freedom Vortex-Induced Vibration (VIV) of two rigidly coupled circular cylinders of different diameters at a low Reynolds number of 250 is investigated numerically. While the diameter ratio and the mass ratio are kept constant, the study is focused on the effect of the position angle of the small cylinder on the lock-in regime of the VIV. Simulations are carried out for position angles α of the small cylinder ranging from 0° to 180° with an interval of 22.5° and the reduced velocities ranging from 1 to 15 with an increment of 1. In order to find the effect of the gap between the two cylinders on the vibration, two gap-to-diameter ratios (0 and 0.2) are considered. It is found that compared with a single cylinder case, the lock-in regime of the reduced velocity is widened significantly when the position angle of the small cylinder is α = 0°, 22.5°, 90°, or 112.5°. Pulsed beating phenomenon characterized by regular vibration with occasional high-amplitude disturbances at regular or irregular intervals is observed at G = 0 and α = 90°. At α = 135°, more than one lock-in regimes are observed in the computed range of reduced velocity for both gaps (G = 0 and 0.2). Setting a small gap (gap-to-diameter ratio of 0.2) between the two cylinders mitigates the vibration by narrowing the lock-in regime and reducing the vibration amplitude.