Experiments are conducted in this study to investigate the size of air bubbles formed from orifice diffusers in a water tank. The size of individual bubbles and the Sauter diameter are evaluated using an image processing technique. The results confirm that the air flow rate and the nozzle diameter are important parameters controlling the bubble size distribution and Sauter diameter. Dimensional analysis is performed to provide a general dimensionless relationship for the bubble Sauter diameter by using an appropriate length scale, which is based on the air flow rate, and the Reynolds number at the nozzle exit. This relationship fits well the experimental data from this study and previous investigations available in the literature, also including experiments for multiple orifice diffusers. Finally, potential applications of the dimensionless relationship obtained here are presented.
bubbles; dimensional analysis; image processing; plumes; Sauter diameter
