Effect of flow direction and capillary orientation on the bubble detachment diameter in liquid cross-flow

The process of bubble detachment from an orifice or capillary in the liquid flow was studied experimentally. The effect of liquid viscosity, orifice orientation, and flow direction were investigated. It was shown that the smallest bubbles were obtained when the capillary was placed across the flow in the channel center. The largest bubbles were produced when the capillary was oriented along the flow. A comparison of several theoretical and semi-empirical models with experimental data obtained was performed. A qualitative model was proposed to predict the size of bubble produced, taking into account the bubble coalescence near the capillary. The study demonstrates that the average dimensionless volume of generated bubbles is influenced by factors such as capillary diameter, liquid velocity, and viscosity, as long as the gas flow rate remains below a critical value. However, beyond this critical gas flow rate, the dimensionless bubble volume values of different experimental parameters align along a single curve in the suggested dimensionless coordinates.