Experimental study of interfacial characteristics of vertical upward air-water two-phase flow in 25.4 mm ID round pipe

An adiabatic upward air-water flow experiment was performed on a vertical pipe with 25.4 mm inner diameter to investigate the interface structure and characteristics. Local experiment parameters, including time-averaged void fraction, interfacial area concentration, bubble interfacial velocity and Sauter mean diameter were measured using a four-sensor conductivity probe with a data acquisition frequency of 100 kHz. Experiment data for 19 flow conditions was collected at 3 axial locations (z/D = 15, 78, and 141) and 13 radial positions from r/R = −0.84 to 0.7. In the experimental study, the measuring range of superficial liquid and gas velocity were from 0.3 to 1.0 m/s and 0.03 to 11.0 m/s, respectively. The flow regimes ranged from bubbly flow to the transition of churn-turbulent to annular flow. The local measurement result agreed well with the drift flux model by Ishii (1977) and Kataoka (1987). The different interfacial structures in different flow regimes and two group bubble interfacial transfer were observed from the experiment result. This data will be used for the evaluation and extension of the current interfacial area transport equation.