Oscillating microbubbly flows generated by a fluidic oscillator: Flow behavior and mass transfer characteristics

Abstract In this study, a Coanda‐swept fluidic oscillator is used to generate oscillating microbubbly flows. Flow behavior measurements show that the generated microbubbly flows have periodic sweep characteristics. Massive microbubbles are generated by shear‐off‐induced breakup, dynamic erosion breakup, and wall‐fluid‐shear‐induced breakup within the fluidic oscillator. Mass transfer measurements show that the generated microbubbly flows have a higher interfacial area ( a ) and volumetric liquid‐side mass transfer coefficients ( k L ) than the other comparison groups. Furthermore, the energy efficiency is assessed in terms of k L per energy consumption ( η ) and energy consumption per a ( ξ ). For the fluidic oscillator group, the highest k L a is 0.089 s −1 , corresponding to ( η = 0.63 m 3 /(kW·s), ξ = 2.6 J/m 2 , a = 785 m 2 /m 3 ). Although it has been reported that higher k L a is typically associated with lower energy efficiency, the results indicate that the fluidic oscillator is a promising microbubble generator.