剪切来流作用下圆柱体结构物的双自由度流致振动

基于四步半隐式特征线分裂算子稳定化流体有限元方法,对二维线性剪切来流作用下弹性支撑圆柱体结构物双自由度流致振动问题进行了数值计算,着重研究雷诺数Re=150时,不同参数(频率比、剪切率与折减速度)对圆柱体结构物振动响应及其流场的影响.计算分析表明,随剪切率的增加,圆柱体结构物2个方向的频率锁定区间扩大,结构发生共振现象的范围亦增大;折减速度对圆柱钝体最大振动幅度的影响较大,在锁定区间内,圆柱振动位移较大,否则较小;在高频率比工况下圆柱运动轨迹呈‘8’字形;当频率较低时,圆柱运动轨迹随剪切率的增大由‘8’字形渐变为‘雨滴’形;在剪切来流作用下圆柱尾流模态为双单涡(2S)与涡对(P)+单涡(S)两种泄涡模式.

Two-Degree-of-Freedom Flow-Induced Vibration of an Isolated Cylinder Structure in Planar Shear Flow

Based on the four-step semi-implicit Characteristic-Based-Split (CBS) stabilized fluid finite element method, the flow-induced vibration of an elastically supported cylinder with two degrees of freedom in 2D planar shear flow was numerically studied. Besides, the effects of some key parameters, such as natural frequency ratio(r), shear ratio(k) and reduced velocity(ur), on vibration response of the cylinder and fluid field around it were analyzed. The results show that the lock-in range and resonant region of the cylinder broaden as k increases. The reduced velocity has a great impact on the maximum vibration amplitude of the cylinder: the amplitude is larger in the lock-in range; however, it becomes small in other cases. It is found that, in the resonant region, the orbital trajectory of the cylinder shows an 8-shaped figure at a larger r, whereas it transfers from the 8-shaped figure motion to a raindrop motion with the increase of k at the lower r. The vortex shedding patterns are 2S and P+S in the shear flow.