Coalescence characteristics of bubbles from submerged micron-sized double-orifice plates: Experiments and modeling

Bubble dynamics is of significance for improving the performance of bubbling. However, few studies focused on the detailed characteristics of bubble formation at micron-sized multiple orifices. Herein, the dynamic behaviors of bubble growth at micron-sized double-orifice plates are visually investigated. The evolution of adjacent bubbles, coalescence frequency, and detachment diameter of the initial bubbles with orifice diameter and spacing, gas flow, and liquid properties are obtained. Based on the experimental data, three dimensionless parameters, Weber number (We), Reynolds number (Re), and Froude number (Fr), are introduced through dimensional analysis. A mathematical correlation between the Sauter mean diameter of bubbles and orifice diameter and spacing, gas velocity, and liquid viscosity and surface tension is established for the first time. The error between the calculated and experimental values is found to be within ± 15 %. The work provides guidance for the understanding and development of bubbling at micro orifices.