Experimental Study of Bubble Dispersion Characteristics in a Nonuniform Electric Field

The application of electric fields can intensify the dispersion characteristics of discrete phase in continuous phase. In charged liquid–gas dispersion systems, there are important processes, such as bubble formation, motion, and interaction, which are quite different from hydrodynamic processes without external fields. In the present study, the bubble dispersion characteristics were experimentally studied in ethanol under a direct current (DC) nonuniform electric field. By considering the voltage and flow rate, the dispersion pattern, trajectory, size distribution, velocity, and deformation of the bubbles were examined using high-speed photography. A considerable control over the bubble dispersion patterns, including isolated, chain, and diffusion patterns, can be achieved by careful consideration of the experimental parameters. The bubbles dispersion in liquid under the electric field can detach with a considerably smaller diameter than that without electric field. Both the increase in electrical Bond number (Bo_E) and gas Reynolds number (Re_g) intensifies the interaction between bubbles. The Bo_E works to accelerate the separation of smaller bubbles, while the Re_g works to reinforce the wake induction. In addition, the cross-sectional bubble size distributions, velocities, and bubble shapes corresponded to the bubble dispersion patterns.