Sub-Regimes of Air-Water Slug Flow Characteristics in Horizontal Pipes by Liquid Hold-up Model Correlated to Bubble Behaviours (LHmBb)

Sub-regimes of air-water slug flow in horizontal pipes have been characterized by a liquid hold-up model correlated to bubble behaviors (LHmBb). The LHmBB is composed of two sections which are the liquid hold-up model and bubble behavior investigations. The liquid hold-up model is developed based on the statistical analysis of the probability density function (PDF) to quantify the bubble distribution. The bubble behaviors are qualitatively investigated based on the high-speed camera and correlated to the quantified LH for the characterization of sub-regime of air-water slug flow. The LHmBB characterizes the sub-regime of air-water slug flow in a horizontal transparent acrylic pipe with an inner diameter of underwater and air superficial velocities of and, respectively. As a result, four sub-regimes are determined as Initially dispersed Bubbles (IdB), Low dispersed Bubbles (LdB), High dispersed Bubbles (HdB), and Dominantly dispersed Bubbles (DdB). The presence of bubbles determines the type of sub-regime by decreasing the number of bubbles and dispersing the bubbles mechanism. Moreover, the proposed LHmBb includes the correlation function to ease the prediction of the sub-regimes of air-water slug flow characteristics which leads to the enhancements of the two-phase flow pattern map in horizontal pipes.