Experimental investigation of upward vertical two-phase high-velocity flows in large-diameter pipes

Abstract

An experimental investigation is carried out to analyze the effect of the diameter and high fluid velocities on two-phase flow in vertical large-diameter pipes. This study generated and gathered experimental data for diameters ranging from 97 to 297 mm. The working fluids for the experimental database are water and air, for superficial liquid velocities ranging from 0.2 to 4.7 m/s; and superficial gas velocities ranging from 0.1 to 30 m/s.From the experimental observations of flow regimes for diameters larger than 97 mm, cap-bubble flow is observed for conditions which slug flow would be expected in smaller diameter pipes. Based on experimental results obtained in this work and available in the literature, it is observed that pressure gradient only varies around 50% for changes of one order of magnitude on the pipe diameter (from 19 to 297 mm), for superficial gas velocities lower than the minimum point in the pressure gradient curve. The measurements of liquid holdup and pressure gradient are compared to a numerical model based on the drift-flux approach, which shows good agreement with the experimental observations.