Upward gas–liquid two-phase flow after a U-bend in a large-diameter serpentine pipe

Abstract

We present an experimental study on the flow behaviour of gas and liquid in the upward section of a vertical pipe system with an internal diameter of 101.6 mm and a serpentine geometry. The experimental matrix consists of superficial gas and liquid velocities in ranges of 0.15 to 30 m/s and from 0.07 to 1.5 m/s, respectively, which cover bubbly to annular flow. The effects on the flow behaviours downstream of the 180° return bend are significantly reduced when the flow reaches an axial distance of 47 pipe diameters from the U-bend. Therefore, reasonably developed flow is attained at this development length downstream of the bend. Other published measurements for large-diameter film thickness show similar trends with respect to the superficial gas velocity. However, the trends differ from those of small-diameter pipes, with which the film thickness decreases much faster with increasing gas flow. As a result, only a few of the published correlations for small pipe data agreed with the experimental data for large pipe film thickness. We therefore modified one of the bestperforming correlations, which produced a better fit. Qualitative and statistical analyses show that the new correlation provides improved predictions for two-phase flow film thickness in large-diameter pipes.

Air–Water Two-Phase Flow Dynamics Analysis in Complex U-Bend Systems through Numerical Modeling

“…It is then followed by a further 200mm vertical upward section, diverging our work from previous works investigating the U-bend effect in the literature. Typically, U-bends are constructed solely as 180-degree return bends [25,28,31,32]. However, in our study, we also examine the pre-effect of the 90-degree upward and downward elbows on the two-phase flow, in The dimensions of the model utilized in this study were specifically designed to be consistent with the physical setup outlined in our previously published studies [10,29,30].…”

“…Limited studies in the literature have also been conducted on 180-degree return bends (U-bends) with various orientations, highlighting a gap in the current research landscape beyond investigations on 90-degree bends. While some of the research has explored the flow regimes and characteristics [23][24][25] and heat transfer enhancements [26][27][28] in 180-degree bends, comprehensive studies on the influence of bend geometry on two and three-dimensional flow dynamics in such configurations are scarce. Furthermore, most of the studies focus solely on pressure drop characteristics [23,25,27].…”

The impact of 180° return bend inclination on pressure drop characteristics and phase distribution during oil-water flow

“…Meanwhile, López et al [ 18 ] , Wang et al [ 19 ], and Yadav et al [ 20 ] employed the photographic technique to identify flow patterns in various contexts. Additionally, Aliyu et al [ 21 ] conducted an experiment on measurements of film thickness and investigated flow pattern transitions at different flow rates. Understanding the impact of U bends on pressure drop has also received attention in the literature.…”

Wall Slip and Flow Characteristics of Gas–Liquid–Solid Phase Coupling Flowing in Horizontal Pipelines

“…Most existing research focuses on the shape, average size, and other parameters of solid particles, and also discusses their influence on the flow characteristics of solid–liquid mixtures while ignoring the effects of flow velocity, pipe size, and wall roughness. − Moreover, oil exploitation is often accompanied by the production of natural gases. Research on gas–liquid two-phase pipe flow based on this background is quite mature, and a variety of flow parameter testing technologies have been developed to study the conventional gas–liquid two-phase flow pattern conversion, pressure fluctuation, and phase distribution. − With the development of unconventional resources in the petroleum industry, research on the flow law of multiphase in pipelines has gradually become an important research topic. It is therefore very important to study the critical parameters of the flow pattern transition under different flow conditions.…”