The instability of void fraction waves in vertical gas-liquid two-phase flow

The measuring and analyzing results of void fraction waves in different flow regimes show that the propagating velocity of void fraction waves depends on flow regimes and mean void fraction. The disturbance at some frequencies can enhance the void fraction wave velocity. Non-linear analysis show that the instability process of bubbly flow is a chaotic process. Before the bubbly flow transits to cap-bubbly flow the growth rate of void fraction waves becomes the maximum value when the disturbance frequency is around the main frequency of void fraction waves.