Investigation on two-phase flow in small diameter non-circular channels under low and normal gravity

Experiments have been performed for two-phase air-water flow under terrestrial (1g0 vertical upwards) and low gravity (μg0) conditions through circular and non-circular channels with different cross-section and equivalent (hydraulic) diameter of dh≈6 mm. Under 1g0-condition three of the four basic flow patterns and under μg0-condition two of the four basic flow patterns were observed depending on the liquid and gas superficial velocity. The transion from dispersed bubble to slug flow (1g0 and μg0) and to churn flow (1g0) is discussed. The influence of the channel geometry on the flow pattern transition as well as the influence caused by the superficial liquid and gas velocity and by the pipe diameter is shown for both low and normal gravity condition.