垂直U形管内气液两相流诱导振动模拟

Numerical Simulation of Gas-liquid Two-phase Flow Induced Vibration in a Vertical U-Tube

采用ADINA数值方法研究了垂直U形管内气液两相流诱导振动的位移响应和脉动激振力特性,然后考察了雷诺数Re和体积含气率β对激振力的影响规律。结果表明:气液两相内流诱导振动以面内振动为主,表现为两相流诱发激振力的主频与管结构某阶固有频率相近时的共振现象;激振力的脉动特性表现为低β时的窄频带随机波动和高β时的周期性波动;固定β时,激振力的均方根值F^(RMS)随Re的增大而增大,增大速率逐渐增加;同一Re下,F^(RMS)先随β的增大而增加,在β=55%左右时达到最大,之后逐渐降低,最大值出现在泡状流向搅拌流的转变过渡区。

The aim of the present study is to investigate the vibration response,pulsating excitation forces characters of the gas-liquid two-phase flow-induced vibration in a vertical U-tube by ADINA numerical method.And the effect of Reynolds number and volume void fraction on excitation forces is studied.The results show that in-plane vibrations occupy dominant component and the vibrations are due to a resonant phenomenon when dominant frequency of excitation force is close to one of natural frequency of tube system.At low volume void fraction,the form of the force corresponds to a narrow-band random excitation.As volume void fraction is increased,periodic force components become dominant.For a given volume void fraction,root mean square of excitation force（F-RMS）increases with the rise of Reynolds number and the rate of increasing raises gradually.For a given Reynolds number,F-RMS increases with increasing volume void fraction,reaching a maximum at roughly 55%volume void fraction beyond which it decreases gradually.And the highest value occurs in the transition zone from bubble flow to churn flow.