大变形柔性管道两相流流致振动研究

针对柔性管道内段塞流引起的结构大变形流致振动问题，本文采用分区强流固耦合方法建立了面向大变形两相流输运管道的双向流固耦合数值计算模型.基于流体体积法对气液两相流动界面进行追踪并结合任意拉格朗日-欧拉(ALE)动网格方法考虑流体域网格变形，同时采用有限元方法建立了柔性管道动力学模型，根据流体和管道壁面的相互作用构建强流固耦合计算模型.研究表明，在两相流作用下柔性管道的振动主要以类似一阶和二阶振动模态响应为主且会发生模态切换；模态切换与管内的液塞长度、液塞流动频率以及气液塞在管内的轴向分布有关；管道的大变形振动促进了短气塞的融合并显著改变了液塞的长度和频率，进而影响管道的振动和流型转变界限.

Investigation on Two-phase Flow Induced Vibration Responses in a Flexible Pipe with Large Deformation

In order to study the flow-induced vibration characteristics caused by gas-liquid two-phase flow in a flexible pipe with large deformation, a numerical simulation platform for partitioned fluid-structure coupling under the condition of the internal two-phase flow has been developed. The interface between the gas and liquid phases is tracked based on the volume of fluid method, and the mesh deformation of fluid domain is considered by the arbitrary Lagrangian-Euler (ALE) dynamic mesh technique. Meanwhile, the flexible pipe is established by the finite element method. The fluid domain and structural domain are coupled by adapting the coupling library preCICE. The results indicate that the and three types of mode switching are identified on the basis of the switching characteristics. The vibration of the large-deformation flexible pipe is dominated by the first order and second order oscillation modes. The mode switching mainly depends on the length, recurrence frequency and the axial distribution of liquid slug in the flexible pipe. The large deformation of the pipe promotes the fusion of the short bubble slug and changes the length of the liquid slug significantly, thus affecting the vibration amplitude and flow pattern transition boundary of the pipe.