Experimental evidence of vortex-induced vibrations at subcritical Reynolds numbers
Experimental evidence of vortex-induced vibrations at subcritical Reynolds numbers
复制标题
亚临界雷诺数下涡激振动的实验证据
DOI：
10.1017/jfm.2021.549
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发表时间：
2021
影响因子：
3.7
通讯作者：
Y. Modarres
中科院分区：
文献类型：
--
作者：
Pieter R. Boersma;J. Zhao;J. Rothstein;Y. Modarres
当雷诺数大于Re=47时，在固定圆柱的尾迹中可以观察到涡的脱落。这可能会给人一种印象，即只有在雷诺数大于$Re=47$时才能观察到涡激振动（VIV），当柔性安装圆柱体尾流中的涡脱落频率与结构的固有频率相等时，才会发生VIV。然而，最近的数值模拟和理论工作表明，在亚临界雷诺数（即雷诺数小于Re=47$）下观察涡激振动是可能的。在这些研究中，涡激振动已被观察到数值低雷诺数为$Re=22$。在目前的工作中，第一个实验证据的涡激振动在亚临界雷诺数。我们已经设计并建立了一个实验装置，使其能够进行VIV实验在亚临界雷诺数，并在一个恒定的雷诺数在整个锁定范围内（即范围内观察到的振荡）。使用这个实验装置，我们已经证实实验，涡激振动确实可以观察到在亚临界雷诺数，通过观察涡激振动雷诺数低至$Re=19$。我们已经观察到亚临界涡激振动时，雷诺数在整个锁定范围内保持不变，当雷诺数随着降低速度的增加而增加，同时保持在亚临界范围内。
Abstract Shedding of vortices can be observed in the wake of a fixed cylinder at Reynolds numbers larger than $Re=47$. This might give the impression that a vortex-induced vibration (VIV), which occurs when the frequency of vortex shedding in the wake of a flexibly mounted cylinder synchronizes with the natural frequency of the structure, could be observed only at Reynolds numbers larger than $Re=47$. Recent numerical simulations and theoretical work, however, have shown that it is possible to observe VIV at subcritical Reynolds numbers, i.e. Reynolds numbers smaller than $Re=47$. In these studies, a VIV has been observed numerically at Reynolds numbers as low as $Re=22$. In the present work, the first experimental evidence of VIV at subcritical Reynolds number is presented. We have designed and built an experimental set-up that makes it possible to conduct VIV experiments at subcritical Reynolds numbers, and at a constant Reynolds number over the entire lock-in range (i.e. the range for which oscillations are observed). Using this experimental set-up, we have confirmed experimentally that VIV can indeed be observed at subcritical Reynolds numbers, by observing VIV at Reynolds numbers as low as $Re=19$. We have observed subcritical VIV both when the Reynolds number stays constant over the entire lock-in range, and when the Reynolds number increases with increasing reduced velocity, while staying within the subcritical range.