The role of wake stiffness on the wake-induced vibration of the downstream cylinder of a tandem pair
The role of wake stiffness on the wake-induced vibration of the downstream cylinder of a tandem pair
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DOI：
10.1017/jfm.2012.606
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发表时间：
2013-02
影响因子：
3.7
通讯作者：
G. Assi;P. Bearman;B. Carmo;J. Meneghini;S. Sherwin;R. Willden
中科院分区：
文献类型：
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作者：
G. Assi;P. Bearman;B. Carmo;J. Meneghini;S. Sherwin;R. Willden
摘要当一对串联圆柱浸泡在水流中时，下游圆柱由于与上游圆柱涡的相互作用而产生尾迹诱发振动。[j] .流体力学。（英文版），vol. 661, 2010, pp. 365-401)得出的结论是，WIV激励机制的起源是当圆柱体在尾流上振荡时遇到的非定常涡-结构相互作用。在本文中，我们研究了圆柱如何响应该激励，表征响应的幅度和频率及其对系统其他参数的依赖。我们引入了尾迹刚度的概念，这是一种流体动力学效应，可以与线性弹簧相关联，其刚度与$\mathit{Re}$成正比，并与交错气缸发生的稳定升力相关联。通过将圆柱体安装在没有弹簧的基座上的一系列实验，我们验证了这种尾迹刚度不仅足以维持振荡运动，而且可以支配系统的结构刚度。我们得出结论，虽然非定常涡-结构相互作用提供了维持振动的能量输入，但尾迹刚度现象定义了WIV响应的特征。
Abstract When a pair of tandem cylinders is immersed in a flow the downstream cylinder can be excited into wake-induced vibrations (WIV) due to the interaction with vortices coming from the upstream cylinder. Assi, Bearman & Meneghini (J. Fluid Mech., vol. 661, 2010, pp. 365–401) concluded that the WIV excitation mechanism has its origin in the unsteady vortex–structure interaction encountered by the cylinder as it oscillates across the wake. In the present paper we investigate how the cylinder responds to that excitation, characterising the amplitude and frequency of response and its dependency on other parameters of the system. We introduce the concept of wake stiffness, a fluid dynamic effect that can be associated, to a first approximation, with a linear spring with stiffness proportional to $\mathit{Re}$ and to the steady lift force occurring for staggered cylinders. By a series of experiments with a cylinder mounted on a base without springs we verify that such wake stiffness is not only strong enough to sustain oscillatory motion, but can also dominate over the structural stiffness of the system. We conclude that while unsteady vortex–structure interactions provide the energy input to sustain the vibrations, it is the wake stiffness phenomenon that defines the character of the WIV response.