Micro-nano bubbles production using a swirling-type venturi bubble generator

• A SVBG was designed to improve the microbubble generation efficiency. • The influence of geometric parameters on the flow structure of SVBG was studied. • The SVBG could shear the bubbles into micro-nano bubbles with size down to 780 nm. • The micro-nano bubble cavitation reactor displayed a superior DO value. We designed a swirling-type venturi bubble generator (SVBG) by introducing a swirling flow field into the conventional venturi tube to improve the microbubble generation efficiency. The fan-shaped baffles were added at the entrance and the converging section was replaced by spiral channel to enhance swirling flow intensity so as to facilitate bubble breakup. The influence of geometric parameters on the flow structure of the SVBG was studied through numerical simulation. Then the optimized SVBG was installed at the downstream of the conventional venturi tube to construct a novel micro-nano bubble cavitation reactor. The manufactured cavitation reactor generated bubbles with size down to 780 nm. Moreover, the cavitation reactor exhibited a superior dissolved oxygen value, which was increased by 36.06% when compared with venturi tube, showing great promise for oxygen enrichment. The micro-nano bubble cavitation reactor presented can provide a more effective way to produce micro-nano bubbles.