Slug and Taylor bubble lengths are important input parameters in equipment sizing and estimating flow parameters in pipes. Although slug flow has been studied for decades, there still exists a lack of comprehensive understanding of flow structures due to the complex interactions of the gas and liquid phases in two-phase flow. This study investigates the influence of pipe inclination on large gas structures, ‘Taylor bubbles’ in slug flow. An experimental study was conducted to estimate the Taylor bubble lengths for an air-silicone oil mixture from void fraction measurement using a twin-plane Electrical Capacitance Tomography (ECT) tool. The results show that the Taylor bubble length increases when the void fraction increases and/or the pipe inclination decreases. The influence of pipe inclination on bubble length is quite significant; this variation in bubble length with pipe inclination is attributed to gas expansion when there is an alteration on the resultant forces acting on the bubble nose. The forces acting on a fully developed Taylor bubble rising in a quiescence liquid are discussed, and a semi-mechanistic model is proposed. An error analysis of the model shows that it predicts the experimental data within 25% of error across all pipe inclinations. In comparison with existing mechanistic and empirical models, the proposed model gave the best performance for all upward pipe inclinations.
Longtong Dafyak is a PhD student with the Fluid and Thermal Engineering research group at the University of Nottingham. Prior to starting her PhD, she worked as a graduate intern with the Drilling and Well Completions team, Total E & P on projects in the Gulf of Guinea. She has a master’s degree in Petroleum Engineering and Project Development from IFP School and a B. Eng. in Chemical Engineering. Her research focuses on the multiphase flow, particularly viscous slug flow in inclined pipes; she is supervised by Dr Buddhika Hewakandamby and Dr David Hann.
Faculty of EngineeringThe University of Nottingham Nottingham, NG7 2RD
email:flute@nottingham.ac.uk