Formation of bubbles at submerged orifices - Experimental investigation and theoretical prediction

The present work reports an experimental investigation on bubble release through submerged orifices. Bubble frequency has been measured as a function of gas flow rate for three different orifice sizes at various pool heights. Needle type conductivity probe has been used for bubble count. Analysis of probe signal not only gives the bubble frequency but also indicates a transition from bubbling to jetting regime. Further, to validate the experimental observations a simple mechanistic model has been developed considering the evolution of non-spherical bubbles at the orifice mouth. Reasonable agreement between the model prediction and the experimental result has been observed.