低雷诺数下偏心扭转圆柱涡激振动特性研究

VORTEX-INDUCED VIBRATION OF AN ECCENTRICALLY ROTATING CIRCULAR CYLINDER AT LOW REYNOLDS NUMBERS

  • 摘要: 横掠外流冲击下细长圆柱结构涡激振动问题在工程中广泛存在,已有研究多关注圆柱沿横向和/或流向的振动响应,对在涡激扭转振动研究较少。采用流–固耦合数值模拟研究了偏心扭转圆柱在层流中的涡激振动特性。首先,建立了偏心扭转圆柱涡激振动力学模型,推导了控制方程和边界条件。然后,将基于特征线算子分裂的有限元解法、双时间步法、边弹簧近似法、广义–α方法和松耦合迭代解法相结合,针对层流诱发刚体扭转振动开发了一种通用流–固耦合解法,并采用基准算例进行了验证。最后,通过流–固耦合数值模拟,系统分析了偏心距、雷诺数、质量比对层流中偏心扭转圆柱涡激振动振幅、频率、流体载荷的影响规律及机理。

     

    Abstract: Vortex-induced vibrations (VIVs) of slender cylindrical structures in cross flow are ubiquitous in engineering applications. In previous studies, VIVs of a circular cylinder in cross-flow and/or streamwise directions have been well investigated, while little work has been done on the angular response. In this paper, VIV features of an eccentrically rotating circular cylinder in laminar flow is studied numerically. Firstly, the mechanics model of VIV of an eccentrically rotating cylinder is established, and the corresponding governing equations and boundary conditions are derived. Subsequently, coupling the characteristic-based split finite element method, dual-time step method, segment spring analogy technique, generalized-α method and loosely-coupled partitioned method, a fluid-structure interaction (FSI) solution procedure for rotational response of a solid body in laminar flow is developed, and its stability and accuracy are examined by using a benchmark vortex-induced rotation model. Finally, using FSI simulation, effects of eccentricity, Reynolds number and mass ratio on VIV amplitude, frequency and fluid loads of the eccentrically rotating cylinder are investigated in details.

     

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