Empirical Equations for Bubble Formation Frequency from Downward-Facing Nozzle with and without Rotating Flow Effects

Bubble formation from a downward-facing single-hole nozzle immersed in a still circular water bath has been observed with a high-speed video. An empirical equation is derived for the frequency of bubble formation, f B 0 , as a function of gas flow rate Qg, the inner and outer diameters of the nozzle, d n i and d n o , the acceleration due to gravity, g, and the physical properties of fluids. A cross-flow is imposed on the nozzle by rotating the bath around its vertical axis. The frequency of bubble formation in the presence of the rotating flow, f B , is predicted using /go and the rotating flow velocity, u θ .