同心圆排布管束流体弹性不稳定性模拟研究

流体弹性不稳定性是换热器管束振动中最重要的激振机理,对同心圆排布管束的流体弹性不稳定性研究可以为该类型换热器的设计制造及维护提供参考。基于同心圆排布的几何特点,建立了类正方形排布、过渡排布和类三角形排布3个具有代表性的物理模型,采用 ANSYSCFX软件进行了流固耦合模拟计算,获得流场信息和振动特性。通过对同心圆排布不同位置处的临界流速、主振方向进行分析,发现主振方向会随间隙流速增大,由顺流方向变为横流方向;在 3种排列中,类正方形排布区域临界流速最大,过渡排布区域临界流速最小,结果表明,同心圆排布管束中过渡排布最易失稳,在设计及工程应用中应重点关注该区域。

Numerical Simulation of the Fluid Elastic Instability of Concentric Arrays of Tube Bundles

Fluid elastic instability is the most important mechanisms that excite vibration of tube bundles in heat exchangers.The study on fluid elastic instability of concentrically distributed tube bundles can provide valuable guidance for the design,manufacture and maintenance of this type of heat exchangers.Based on the geometric characteristics of concentric arrays,three representative physical models were established,including quasi-square arrangement,transitional arrangement and quasi-triangle arrangement.Flow field and vibration characteristics were obtained from fluid-structure interaction numerical simulation of ANSYS CFX software.The critical velocity and main vibration direction at different positions of concentric arrays were analyzed.It was found that the main vibration direction changed from stream-wise direction to cross-stream direction as the gap flow velocity increased.In the three arrays,the maximum critical velocity appeared in the quasi-square arrangement area,whereas the minimum one occurred in the transition arrangement area.The simulation results show that the transition arrangement was easiest to appear unstable in the tube bundles of concentric arrays,which high attention should be paid to during the design and engineering application.