E​RCOFTAC PC Brazil

Droplet Detachment and Bubble Coalescence at the Tail of a Taylor Bubble in Dense Gas/Liquid Flow

Authors: Edson. S. Orati, Hidaca, G., Perissini, I. C., Bochio, G., Santos, J. N., Rodriguez, O. M. H.
(​Industrial Multiphase Flow Laboratory (LEMI), Department of Mechanical Engineering, São Carlos School of Engineering, University of São Paulo (USP), Brazil)

Droplet detachment from the disintegration of a liquid sheet at the tail of a Taylor bubble, followed by bubble coalescence, was observed in vertical-upward 1-inch ID pipe flow experiments under slug flow. Droplets of different sizes move through the Taylor bubble core and towards the backward film interface with which their physical interactions are intriguing and eye-catching.

Scientific Abstract

A scientific investigation of dense-gas/liquid two-phase flow has been carried out in vertical pressurized tubes with the focus on flow pattern transitions and associated interfacial phenomena. Our research applies to oil and gas production under ultra-deep waters and carbon storage within depleted geological reservoirs, since large content of carbon dioxide, elevated pressures and inaccurate diagnostics from in-situ metering are among the technical challenges. Under these circumstances, the densities of gas and liquid phases are of the same order of magnitude. To circumvent hindrances caused by operation with supercritical carbon dioxide, sulfur hexafluoride (SF6) is used as a substitute from a similitude analysis based on flow characteristics and their physical properties. Since there is a lack of experimental data on flows with dense gas, our research group is devoted to the collection, processing and analysis of data from two-phase flow experiments with mineral oil (density of 850 kg/m3) and SF6 (100 kg/m3). We have been investigating the behavior and interfacial structure of many flow patterns, and their flow transitions in the two-phase flow scenarios of low liquid/gas density ratios at various pipe inclination angles. Liquid holdup, pressure drops, in-situ gas and liquid velocities, film thickness and wire-mesh tomography are measured in the data collecting stage of the current research. During vertical-upward 1-inch-ID pipe flow experiments carried out at 0.2 m/s oil and 0.05 m/s SF6, superficial velocities, droplet detachment and, subsequently, bubble coalescence were observed at the tail of a Taylor bubble using a high-speed video camera at 3000 frames per second with the aid of a 100 mm lens and a HDPro 2X DGX teleconverter.

List of recent publications:

Ruiz-Diaz, C.M., Pacheco, C.E.A., Orati, E.S., Bochio, G., Postal, A.T., Rodriguez, O.M.H. Experimental study on dense-gas/oil flow in horizontal and slightly upward inclined pipes. International Journal of Multiphase Flow, v. 194, p. 105477, 2026. https://doi.org/10.1016/j.ijmultiphaseflow.2025.105477

Gómez-Camperos, J.A., Ruiz-Diaz, C.M., Hernandez-Cely, M.M., Rodriguez, O.M.H., Pardo-Garcia, A. Dense-gas/liquid two-phase flow pattern recognition using convolutional neural networks and transfer learning. International Journal of Multiphase Flow, v. 194, p. 105479, 2026. https://doi.org/10.1016/j.ijmultiphaseflow.2025.105479

Quintino, A.M., Fonseca Junior, R., Rodriguez, O.M. Experimental study of liquid/dense-gas pipe flow. Geoenergy Science and Engineering, v. 230, p. 212179, 2023. https://doi.org/10.1016/j.geoen.2023.212179

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