竖直气液两相管流中空隙率波及其不稳定性分析

VOID FRACTION WAVE AND ITS INSTABILITY IN VERTICAL GAS LIQUID TWO PHASE PIPE FLOW

对竖直气液两相管流中的空隙率波进行了测量和分析。结果表明 ,不同流型的空隙率波其传播速度不同 ,并随含气率的升高而增大 ,泡状流“失稳”前后空隙率波的相速度与群速度不相等 ,属于色散波。利用扰动方法研究了空隙率波的不稳定性 ,发现某些频率的扰动能使空隙率波的波速和相速度有所提高。非线性分析结果表明 ,泡状流“失稳”时是一个混沌动力系统。空隙率波的增长系数求解结果表明 ,泡状流向弹帽泡状流转化时 ,空隙率波对有限扰动是不稳定的 ,并对扰动的频率有所选择。当扰动频率与空隙率波的主控频率相近时 ,空隙率波呈最大增长状态。

The measurement and analysis results of void fraction waves in different flow regimes show that the propagating velocity of void fraction wave depends on flow regimes and mean void fraction. The disturbance at some frequencies can enhance the velocities of phase and void fraction waves. The non linear analysis indicates that the instability of bubbly flow is a chaotic process. Before the bubbly flow transits to cap bubbly flow, the growth rate of void fraction wave becomes the maximum value when the disturbance frequency is close to the main frequency of void fraction wave.