Smaller Bubble Formation from a Horizontally Oscillating Nozzle

Abstract

Fine bubbles are used for cleaning system, separating process, food industry and so on. However, commercially available devices for fine bubble generation cannot be applied for particle dispersion liquid because they need liquid pumps and particles are accumulated on their systems. Moreover, the bubble diameter cannot be controlled in those devices. The uniformed and controlled bubble diameter is important for a reasonable industrial device design. Therefore, in this study, a novel method for fine bubble generation without liquid circulation was developed. A horizontally oscillating micro-nozzle was used to make bubbles small. The effect of the gas flow rate, the oscillating frequency, and the oscillation amplitude on the average bubble diameter was investigated experimentally. Moreover, visualization and quantification of liquid motion around the oscillating nozzle was carried out in this study. It was clarified that the liquid viscous force due to the relative velocity of the nozzle motion to the liquid motion enhances the bubble detachment from the nozzle in this method.