Initial Results from the Experimental and Computational Study of Microbubble Generation

Abstract - In this paper, a novel design of microbubble aeration system is proposed to increase levels of dissolved oxygen in water, by reducing the mean diameter of the bubble distribution down to the 20 – 50 µm range. Microbubble generators (MBG) can find application in aquaculture farms, where water oxygenation is crucial for the growth of sea animals, as well as disinfection through OH- free radicals which are released during the bubble shrinking process. A baseline Venturi MBG is taken as first test for comparison with previous literature to understand the pressure-recovery mechanism responsible of bubble breakup. Based on the performance of Venturi tubes, a helicoidal extrusion at three different pitch angles is added ahead of the throat section, to impress swirling motion to the main flow field, hence, to presumably intensify the turbulent pressure fluctuations responsible for bubble breakup.
Results from Computational Fluid Dynamics method (CFD) and low-speed flow visualisation measurements are compared to verify the CFD model and to assess the overall performance of the bubble generators at different volumetric qualities. Backlight imaging method and two-dimensional binary processing are implemented to estimate the microbubble distribution for each test case.
Main outcome here. 300 words max for abstract
Although this paper only focuses on the bubble diameter, dissolved-oxygen measurements (DO) coupled with the analysis of microbubble distributions will reinforce our assumption that small microbubbles represent the optimal condition to maximise water aeration and to enhance treatment of organic particles such as biofloc.