Predicting mean size and velocity of entrained drops in gas-liquid annular two-phase flow

• New prediction method for Sauter mean diameter of entrained drops in annular flow • New prediction method for mean velocity of entrained drops in annular flow • Large and diversified annular flow experimental databank collected from literature • Annular flow experimental databank critically analyzed • Annular flow experimental databank provided in full and usable form Annular flow is a two-phase flow regime where the gas phase flows in the center of the channel carrying liquid drops in suspension and dragging a liquid film along the channel walls, and is commonplace in two-phase fluid systems. The drops entrained in the gas phase play a key role in the transport of mass, momentum, and heat between the phases, and knowledge of their size and velocity is important in the analysis of annular flows. This study introduces two new prediction methods for the size and for the velocity of the entrained drops in annular flow. The new drop size prediction method provides the Sauter mean diameter of the drops as a function of the properties of the phases and their superficial velocities. This new methodology has simple formulation, outperforms prediction methods from the literature, and holds promise for wider practical applicability on account of the broad underlying experimental data bank, which is significantly broader than those employed previously. The new drop velocity prediction method is the first methodology proposed to date for entrained drops in annular flow, and provides the velocity of the drops as a function of the Stokes number of the drops, which is estimated by solving analytically the equation of motion for the drop. The new prediction methods have been designed by means of a diversified experimental data bank collected from the literature (727 data points from 25 literature studies), which is critically analyzed and that is provided herein in full and usable form.