Liquid transport behavior and influencing factors in vertical T-junctions

The gas–liquid two-phase flow inside the T-junction is significant in industrial production and widely used in chemical engineering, petroleum, and biomedicine. To precisely control the liquid flow direction and entrainment ratio in T-junctions, this study conducted numerical simulations of liquid falling under varying fluid parameters in a vertical T-junction, with experimental validation confirming simulation accuracy (deviation < 8.79%). The gas–liquid two-phase transport behavior was analyzed, elucidating the transition mechanisms of liquid flow direction and investigating the influence of fluid parameters on entrainment ratios. Results demonstrate that liquid transport in vertical T-junctions exhibits highly complex behavior. There are two critical states for the liquid transport behavior at different gas velocities: the complete entrainment boundary and the critical entrainment boundary. Two boundaries divide the liquid entrainment ratio into three distinct regions: the liquid rises completely (entrainment ratio = 1), the liquid falls completely (entrainment ratio = 0), and the transition region (entrainment ratio = 0–1). The liquid entrainment ratio varies nonlinearly from 0 to 1 in the transition region. A single critical entrainment ratio model cannot fully describe the variation process of liquid flow direction inside the T-junction. This work achieves large-scale three-dimensional numerical simulation of gas–liquid transport in T-junctions, providing theoretical foundations for industrial applications.