A visualized investigation on bubble transportation and breakup in a small Venturi channel with rectangular cross section
Microbubble technology is often employed in waste water treatment, biochemical reactor etc. Sizes and distribution of bubbles play a key role in these applications. Because of its simplicity, reliability and high efficiency in producing tiny bubbles, Venturi-type bubble generator receives increasingly attention in recent years. Several kinds of bubble generators have been developed for generating bubbles with required sizes. In this study, an experimental investigation is carried out to study the size distribution of bubbles in a Venturi channel. The experimental results showed that the volume averaged bubble diameter has a −1.15 power dependence on the Reynolds number, with a good agreement with the theoretical derivation. On the other hand, the detailed breakup process of bubbles was recorded by a high speed camera. In the diverging section, the bubbles experienced a rapid deceleration, a significant deformation, and were finally split or even broken up into a great many of tiny or micro bubbles nearby the stagnation region.