Experimental investigation of air–water, two-phase flow regimes in vertical mini pipe

In this study, the flow patterns of air–water, two-phase flows have been investigated experimentally in a vertical mini pipe. The flow regimes were observed by a high speed video recorder in pipes with diameters of 2, 3 and 4 mm and length 27, 31 and 25 cm, respectively. The comprehensive visualization of air–water, two-phase flow in a vertical mini pipe has been performed to realize the physics of such a two-phase flow. Different flow patterns of air–water flow were observed simultaneously in the mini pipe at different values of air and water flow rates. Consequently, the flow pattern map was proposed for flow in the mini-pipe, in terms of superficial velocities of liquid and gas phases. The flow pattern maps are compared with those of other researchers in the existing literature, showing reasonable agreement.