3D (2D space and time) experimental analysis of vertical slug flow – part 1: Air - Water

Slug flow is one among the different flow patterns that two-phase flows can assume and is composed of a Taylor bubble and a liquid slug. The transient and intermittent behaviors of this kind of flow demand that its characteristics must be determined. In this study, an experimental characterization of the vertical upward slug flow in a 0.050-m ID, 15-m-long vertical pipe was developed. Air-water experiments were carried out, with both the gas and the liquid superficial velocities ranging from 0.4 to 3.5 m/s. Four ring conductance sensors and one capacitive wire-mesh sensor were deployed in the test sections to measure the characteristics parameters, namely the Taylor bubble velocity, the unit-cell frequency, the Taylor bubble and the liquid slug lengths and gas fractions, with the aim of evaluating the distribution and evolution of each parameter. A comparison with the unit-cell model showed deviations in gas fraction and pressure drop predictions that originated from simplified assumptions such as a constant liquid film thickness and the absence of dispersed bubbles in the liquid film.