Proposed Treatment on Upward Mixed Phase Flow of Gas and Liquid in Vertical Pipe

Some systematic treatments are proposed on typical flow models, force balance and fluid friction in gas-liquid mixed phase flow through vertical pipe.Various flow patterns which appear in mixed-phase flow may be classified into two typical flow models of bubbling flow and annular flow with liquid entrainment.Force balance in fluids shows that, neglecting the effect of acceleration, pressure drop is contributed by two forces of wall friction and the effects of gravity on the fluids, and the relation is given by Eq.(15).The investigations on liquid hold-up and wall friction become essential for the systematic development of flow phenomena.Wall friction is examined in terms of “two-phase friction factor” by Eq.(18), based on experimental data.For the range of high gas rate and high liquid rate, the “two-phase friction factor” is found to be correlated a curved line by liquid Reynolds number with ±30% deviation, as shown in Fig. 6, and the correlation curve is compared with that of single phase flow through smooth pipe.The correlation curve indicates that there are two basic flow mechanisms of pseudo-stream line and turbu-lent flow in mixed-phase flow, and the transition to turbulent flow occurs gradually along this curve.