单相流作用下圆柱结构振动响应特性研究

The Vibration Response to the Single-phase Cross Flow for the Cylindrical Structure

圆柱结构在单相流作用下的振动响应特性对于管道流致振动的分析与控制有重要的工程实践意义.以质量比为3.94的直圆柱管和弯圆柱管结构为研究对象,在水流流速为0.45~2.5 m/s范围内测试两种圆柱管结构在不同来流速度下的横流向、顺流向振动响应,分析两种圆柱管结构在单相流作用下的振动特性异同.研究表明,在湍流抖振阶段,直圆柱管与弯圆柱管振动幅值差异较小;在漩涡脱落阶段,两种圆柱管结构的横流向振幅出现“初始分支”且漩涡脱落对直圆柱管的作用更加明显.当雷诺数为7500~42000时,直圆柱管和弯圆柱管结构的漩涡脱落频率均随流速增大而增大,且在相同流速条件下直圆柱管漩涡脱落频率较低;直圆柱管和弯圆柱管在横流向未出现“锁频现象”,而顺流向的振动频率“锁定”在固有频率附近,且直圆柱管出现该现象的流速范围较小.

The vortex induced vibration for the cylindrical structure under the single-phase flow are of great significance in engineering practice.The present experiment is carried out on the straight cylindrical tube and curved cylindrical tube with mass ratio 3.94 and the flow velocity between 0.45-2.5 m/s.The in-line flow direction and cross flow direction vibration responses of the two kinds of cylindrical tube structures under different flow velocities were tested respectively.The results show that in the turbulent buffeting stage,there is no obvious difference in the vibration amplitude between the straight cylindrical tube and the curved cylindrical tube,but in the vortex shedding stage,the transverse flow amplitudes of the two kinds of cylindrical tube structures appear“initial branch”and the effect of vortex shedding on the straight cylindrical tube is more obvious.When the Reynolds number is 7500 to 42000,the vortex shedding frequency of straight cylindrical tube and curved cylindrical tube increases with the increase of flow velocity,and the vortex shedding frequency of straight curved cylindrical tube is lower at higher flow velocity.The frequency locking phenomenon does not occur in the transverse flow direction of the straight cylindrical tube and the curved cylindrical tube,on the other hand,the vibration frequency along the flow direction is locked near the natural frequency,and the velocity range of this phenomenon in the straight curved cylindrical tube is smaller than that in the curved cylindrical tube.