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利用计算流体动力学(CFD)方法数值模拟Re=200时不同截面形状弹性支撑柱体的流致振动现象。柱体运动简化为质量-弹簧-阻尼系统。柱体周围流场采用Fluent求解,将Newmark-β方法代码写入用户自定义函数(UDF)求解振动方程,柱体与流场间的非线性耦合作用通过动网格技术来实现。研究不同截面形状对柱体振动形式的影响,圆柱和六边形柱在整个频率比变化范围内始终表现为涡激振动,而方柱和三角形柱随频率比的增大则发生由驰振向涡激振动的转化,捕捉到转化的临界频率比。考虑了流向振动对横向振动的影响,得到了两自由度模型柱体的质心运动轨迹,结果表明柱体以横向振动为主。分析了气动力系数、位移特征值和尾流区涡结构随频率比的变化,获得“拍”和“相位开关”等重要现象,验证了该文数值模拟方法的正确性。
Computational fluid dynamics (CFD) method is used to numerically simulate the flow induced vibration of columns with different cross sections under Re = 200. Cylinder movement reduced to mass - spring - damping system. The flow field around the cylinder is solved by Fluent. The Newmark-β method code is written into the user-defined function (UDF) to solve the vibration equation. The nonlinear coupling between the cylinder and the flow field is achieved by moving mesh technology. The influence of different cross-section shapes on the vibration form of the column is studied. Cylindrical and hexagonal columns always show vortex-induced vibration in the whole range of frequency ratio, while those of square and triangular columns increase with the frequency ratio, Vortex-induced vibrational transformations capture the critical frequency ratio of transformation. Considering the influence of flow vibration on transverse vibration, the trajectory of mass center of two-degree-of-freedom model cylinder is obtained. The results show that the cylinder is mainly transverse vibration. The aerodynamic coefficient, the displacement characteristic value and the vortex structure in the wakes are analyzed. The important phenomena such as “beat” and “phase switch” are obtained. The correctness of the numerical simulation method is verified.