Experimental study on the bubble generation characteristics for an venturi type bubble generator

Bubble generation plays a significant role for mass transfer. An experimental study was performed in a Venturi type bubble generator to evaluate the development of the bubble size distribution in the turbulence flow of an air-water system. As the air stream enters into the flowing water stream through small feedholes, it breaks into bubbles in the diverging section of the venturi tube. Based on the results of Kress's formulation on turbulence dissipation rate, the bubble size correlation with the Reynolds number and the surface tension coefficient was derived. For purpose of validation, the bubbly flow under various Re and gas volume ratios was measured by visualization technique. The experimental data proved that the volume averaged bubble diameter has a -1 power dependence on the Re, which agrees well with the theoretical derivation. Also, it is found that the bubble size is a linear function of the gas volume ratio and a revised formulation which includes the gas volume ratio effect was proposed. (C) 2015 Elsevier Ltd. All rights reserved.