基于绝对节点坐标法的复杂构型输流管道简支支承设计研究

DESIGN OF SIMPLY SUPPORT FOR FLUID-CONVEYING PIPE WITH COMPLEX CONFIGURATIONS BASED ON ABSOLUTE NODE COORDINATE FORMULATION

输流管道广泛应用于海洋、核电、航空航天等重大工程领域,因管道与流体间的耦合效应,在流体作用下管道会出现屈曲、颤振等失稳行为.一般而言,边界支承对管道动力学特征有着重要影响,不同支承位置显著影响管道的稳定性与振动特性.当前关于管道流固耦合动力学的研究大多集中于单一的直管或规则型弯管(如弧型、半圆型和正弦型等),对于实际工程中常见的复杂构型管道,比如L型、S型和U型等,研究还较为少见.文章基于绝对节点坐标法(absolute node coordinate formulation, ANCF)建立了具有普适性的非线性振动理论模型,可用于解决任意构型和任意支承边界下输流管道动力学问题.以L型、S型和U型3种典型构型输流管道为研究对象,首先开展了收敛性分析,找出合适的计算单元数.然后借助CFD仿真结果与理论模型进行对比验证,计算结果表明,相较于有限元方法,基于绝对节点坐标法建立的理论模型在预测复杂构型输流管道的非线性变形时,具有更高的计算效率.基于该理论模型,研究了简支支承位置对3种构型输流管道的固有频率、屈曲位移和应变特征的影响规律.研究发现,存在最优简支支承位置使得输流管道基频达到最大、屈曲位移和应变的极值达到最小.本研究为提高工程中管道的稳定性与使用寿命提供了理论依据与设计指导.

The pipe conveying fluid is widely utilized in ocean,nuclear power,aerospace and other significant engineering applications.Due to the coupling effect between the pipe and fluid,buckling and flutter behaviors may occur when the pipe is subjected to internal fluid flows.In general,the boundary condition has an important effect on dynamic behaviors of the pipe,especially when the support condition is at different locations.Most of previous studies focus on dynamics of straight or regular curved pipes(e.g.arc,semicircular and sin shapes),few researches concern on pipes with complex configurations like L,S and U shapes,which are indeed commonly applied in engineering fields.A general theoretical model is established by virtue of absolute node coordinate formulation(ANCF)in this paper,which can be used to solve dynamic problems of the fluid-conveying pipe with arbitrary configurations and boundary conditions.Considering three typical configurations,namely,L,S and U shapes of the pipe conveying fluid.Firstly,the uniform convergence analysis is carried out for the established theoretical model,to find applicable number of computational elements.Subsequently,the results of CFD simulation method is used to compare with and validate the theoretical model.The results show that compared to the finite element method,the theoretical model based on the absolute node coordinate formulation has higher computational efficiency when predicting the nonlinear deformations of pipe conveying fluid with complex configurations.Based on the theoretical model,the effects of support position on natural frequency,buckling displacement and strain of the three considered pipes are investigated.The results also show that there is an optimal position of the support where the fundamental frequency reach the maximum,while buckling displacement and strain of the pipe reach the minimum.This study can provide theoretical basis and design guidance for improving the stability and lifetime of pipes in engineering.