Sub‐regimes of air‐water slug flow characteristics in horizontal pipes by liquid hold‐up model correlated to bubble behaviors (LHmBb)

The air-water slug flow sub regimes in horizontal pipes were characterized by a liquid hold-up model correlated to bubble behavior (LHmBb). The LHmBB has two sections, the liquid hold-up model and bubble behavior investigations. The liquid hold-up model was developed based on the statistical analysis of the probability density function (PDF) to quantify the bubble distribution. Specifically, the distribution was qualitatively investigated based on the high-speed camera and correlated to the quantified LH to characterize the sub-regime of air-water slug flow. The LHmBB characterized the air-water slug flow sub-regimes in a horizontal transparent acrylic pipe with an inner diameter of ∅= 0.026 m under air and water superficial velocities of JG = 0.31 − 6.00 m/s JL = 0.20 −0.44 m/s, respectively. As a result, four sub-regimes were determined as Initially dispersed Bubbles (IdB), Low dispersed Bubbles (LdB), High dispersed Bubbles (HdB), and Dominantly dispersed Bubbles (DdB). The decreasing number of bubbles and dispersing bubbles mechanism determined the type of sub-regime. The proposed LHmBb included the correlation function to ease the prediction of the sub-regimes of air-water slug flow characteristics, leading to the two-phase flow pattern map in horizontal pipes enhancement.