Purpose)

In this study, for the first time, the efficacy of control rods for full suppression of vortex-induced vibrations (VIV) and galloping of an elastically supported rigid square cylinder that vibrates freely in the cross-flow direction is investigated.

Design/methodology/approach

To this aim, two small control rods are placed at constant angles of ± 45° relative to the horizontal axis and then the influence of diameter and spacing ratios on the oscillation and hydrodynamic response along with the vortex structure behind the cylinder is evaluated in the form of nine different cases in both VIV and galloping regions.

Findings

The performed simulations show that using the configuration presented in this study results in full VIV suppression for the spacing ratios G/D = 0.5, 1 and 1.5 at the diameter ratios d/D = 0.1, 0.2 and 0.3 (D: diameter of square cylinder, G: distance between rods and cylinder, d: diameter of rods). On the contrary, a perfect attenuation of galloping is only achieved at the largest diameter (d/D = 0.3) and the smallest spacing ratio (G/D = 0.5). In general, for both VIV and galloping regions, with increasing diameter ratio and decreasing spacing ratio, the effect of the control rods wake in the vortex street of square cylinder gradually increases. This trend carries on to the point where the vortex shedding is completely suppressed and only the symmetric wake of control rods is observed.

Originality/value

So far, the effect of rod control on VIV of a square cylinder and its amplitude of oscillations has not been investigated.

中文翻译：

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使用两个不同尺寸和距离的控制杆在锁定和飞驰区域对方圆柱体的横向 FIV 抑制

目的）

在这项研究中，首次研究了控制杆对完全抑制涡激振动 (VIV) 和在横向流动方向上自由振动的弹性支撑刚性方形圆柱体的疾驰的功效。

设计/方法/方法

为此，两个小控制杆相对于水平轴以 ± 45° 的恒定角度放置，然后以表格形式评估直径和间距比对振荡和流体动力响应以及圆柱体后面涡流结构的影响VIV 和 galloping 区域中的九个不同案例。

发现

执行的模拟表明，使用本研究中提出的配置，在直径比 d/D = 0.1、0.2 和 0.3（D：方圆柱的直径，G：杆与圆柱体之间的距离，d：杆的直径）。相反，只有在最大直径 (d/D = 0.3) 和最小间距比 (G/D = 0.5) 时才能实现完美的驰骋衰减。总的来说，对于VIV区和疾驰区，随着直径比的增大和间距比的减小，控制棒尾迹在方柱涡街中的作用逐渐增强。这种趋势持续到涡旋脱落被完全抑制并且仅观察到控制棒的对称尾流的程度。

原创性/价值

到目前为止，尚未研究杆控制对方圆柱体的 VIV 及其振荡幅度的影响。