Modeling of liquid film thickness around Taylor bubbles rising in vertical stagnant and co-current slug flowing liquids

Abstract

The hydrodynamic study of the liquid film around Taylor bubbles in slug flow has great significance for understanding parallel flow and interaction between Taylor bubbles. The prediction models for liquid film thickness mainly focus on stagnant flow, and some of them remain inaccurate performance. However, in the industrial process, the slug flow essentially is co-current flow. Therefore, in this paper, the liquid film thickness is studied by theoretical analysis and experimental methods under two conditions of stagnant and co-current flow. Firstly, under the condition of stagnant flow, the present work is based on Batchelor's theory, and modifies Batchelor’s liquid film thickness model, which effectively improves its prediction accuracy. Under the condition of co-current flow, the prediction model of average liquid film thickness in slug flow is established by force and motion analysis. Taylor bubble length is introduced into the model as an important parameter. Dynamic experiments were carried out in the pipe with an inner diameter of 20 mm. The liquid film thickness, Taylor bubble velocity and length were measured by distributed ultrasonic sensor and intrusive cross-correlation conductivity sensor. Comparing the predicted value of the model with the measured results, the relative error is controlled within 10%.