Size Distribution and Mean Diameter of Microbubbles in Different Types of Ejector Bubble Generators

This study investigates the influence of air discharge on bubble size distribution across various types of bubble generators. Air discharge rates were adjusted between 0.1 lpm and 1.0 lpm for ejector, ejector-barrier plate, and venturi bubble generators, under a controlled experimental setup. High-speed camera footage captured bubble images, which were then analyzed to determine size distributions. A predictive correlation for bubble size distribution was formulated using the Buckingham Pi theorem. Results revealed that increased air discharge correlated with larger bubble diameters, with average increases of 8.01%, 10.71%, and 9.25% for ejector, ejector-barrier plate, and venturi generators, respectively. Notably, the ejector-barrier plate generator exhibited the greatest capability for producing smaller bubbles, with a peak increase in the probability density function of 13.95% for the ejector type, 18.05% for the ejector-barrier plate type, and 9.49% for the venturi type. Experimental findings aligned well with the proposed predictive model for average diameter and bubble size distribution.