气液两相环状流诱发管道振动模型研究

Research on the model of gas-liquid two-phase annular flow induced vibration in piping system

根据两相流动过程中弹性恢复力、离心力、科氏力、惯性力的平衡关系,并考虑因管道弯曲产生的非线性因素,建立了气液两相环状流诱发两端简支管道振动的模型;采用Galerkin方法对模型进行离散化处理,得到了系统的非线性矩阵方程。通过对方程系数矩阵线性部分的求解,具体分析了不同折算流速以及不同弹性模量下管道前四阶模态的量纲归一化特征值的实部及虚部之间的变化规律。结果表明:当折算液速一定时,随着折算气速的增大,管道系统的前4阶固有频率会不断减小;在不同的折算液速下,随着折算气速的增大,管道系统会呈现不同的状态;管道的弹性模量对管道的振动也有着较大的影响。通过对整个方程的求解,分析了管道横向振动位移的规律。研究结果表明:弹性模量较小时,管道的振动位移情况较为复杂;而弹性模量较大时,在同样的折算流速下,管道在平衡位置做振幅较小的周期性往复运动。

A model of gas-liquid two-phase annular flow induced vibration in simply supported piping system is derived based on the equilibrium relation among the elastic restoring force, centrifugal force, Coriolis force and inertial force during the process of flow. The non-linear factors due to the bending of the pipe are also concerned. The model is discretized into a matrix equation by using the Galerkin method. The linear part of the coefficient matrix of the equation is employed to analyze the variation of the imaginary and real parts for the lowest four natural frequencies under different superficial velocities and elasticity modulus. The transverse vibration displacement of the pipe is also analyzed by calculating the whole coefficient matrix of the equation. The results show that if the liquid superficial velocity keeps constant, the natural frequency of the pipe system will decrease with the increase of the gas superficial velocity. Meanwhile, under the condition of different liquid superficial velocities, the pipe system could be in various states with the increase of the gas superficial velocity. Elasticity modulus of the pipe could have a great effect on the vibration of the pipe system.