Bubble formation and bubble-wall interaction at a submerged orifice

Abstract

A fundamental non-spherical model has been developed by means of the boundary integral method for bubble formation at a submerged orifice. This model was validated by comparison of the theoretical predictions with experimental results. To study the wall effect of the bubble column on bubble formation experimentally, three sizes of bubble column were designed. In addition, the effects of chamber volume, gas flow rate and orifice diameter on bubble formation were investigated. To study the wall effect theoretically, a specific system of images was introduced into the fundamental non-spherical model to satisfy the no-flux boundary condition on the impermeable column wall. Comparison of experimental results for bubbling frequency with the theoretical predictions shows that the agreement is good. To thoroughly understand the underlying mechanism and take into account the bubble-bubble interaction as well as the bubble-wall interaction, a further spherical model was developed using potential flow theory. It is observed that this model can predict the bubble formation process very well and it also can predict the occurrence of pairing and multiple bubbling.