质量比对圆柱涡激特性的影响研究

Influences of mass ratio on vortex induced vibration characteristics of a circular cylinder

采用有限体积法对不同质量比圆柱在限制流向及不限制流向下的涡激振动进行了研究。圆柱涡激振动系统简化为质量-弹簧-阻尼模型,引入雷诺平均应力模型求解不可压缩黏性Navier-Stokes方程,结合SST k-ω湍流模型对限制流向和不限制流向下圆柱涡激振动进行了数值模拟。研究发现:限制流向和不限制流向时圆柱涡激振动横向振幅均出现了初始激励分支和下端分支,不限制流向质量比2.0时还出现了超上端分支,其横向振幅最大值为1.05D,是限制流向工况的1.81倍,质量比越大两者相差越小;限制流向和不限制流向两种工况下圆柱涡激振动均发现频率锁定现象,但锁定区间不同;质量比大小对圆柱涡激振动锁定区间也有影响;最后对不同质量比下圆柱涡激振动轨迹进行了讨论分析。

The finite volume method was used to simulate vortex-induced vibration of a circular cylinder under stream-wise limited and unlimited considering different mass ratios. The vortex-induced vibration system of the circular cylinder was simplified into a mass-spring-damping model. Reynolds-Averaged stress model was introduced to solve Navier-stokes equations under incompressible and viscous conditions. Combining with SST（ Shear-Stress Transport） k-ωturbulence model,the vortex induced vibration of the circular cylinder under streamwise linited and unlimited was simulated. The study results showed that the initial branch and lower branch of transverse vibration amplitude occur both in streamwise limited and unlimited cases; for mass ratio of 2. 0,the upper branch occurs in streamwise unlimited case,its maximum transverse amplitude is 1. 05 D,it is 1. 81 times of that in streamwise limited case,the larger the mass ratio,the smaller the difference; the Lock-in phenomenon is found both in streamwise limited and unlimited cases,but the Lockin intervals are different; the mass ratios also have influences on lock-in intervals of the circular cylinder’s vortex-induced vibration. Finally,the trajectories of the vortex-induced vibration of the circular cylinder under different mass ratios were discussed.