Flow patterns and their transitions of vertically downward two-phase flow with high viscosity liquid

The flow patterns and their transitions of air-oil two-phase flows in a vertically downward pipe were investigated experimentally and theoretically. The pipe diameter was 29mm,and the oil and air superficial velocity were up to 4m/s and 20m/s respectively. The flow pattern identifications were carried out by means of the combination of visual observations and analysis for corresponding pressure drop pulsation signals. The investigations express that the flow patterns and their transitions of oil and gas two-phase flow somewhat differed from those of low viscous liquid and gas two-phase flows. On the basis of this study and other previous investigations, one available approach is presented to predict the flow patterns and their transitions in vertically downward two-phase flow with high-viscosity liquid.