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

Abstract

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_B0, as a function of gas flow rate Q_g, the inner and outer diameters of the nozzle, d_ni and d_no, 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 f_B0 and the rotating flow velocity, v_θ.