Experiments on Electrostatic Dispersion of Air in Water

The objective of this work is to investigate bubble generation of air in water through electrified metal capillaries. Many important factors that affect the formation of bubbles, including capillary size, capillary tip configuration, electrode distance, and flow rate, are studied. It is found that the bubble size decreases with increasing applied voltage and decreasing airflow rate. A dimensional analysis of the system parameters is also pursued. The dimensionless numbers are correlated into an empirical model that can be used for the prediction of the bubble size as a function of the applied voltage and airflow rate. It is found that the bubble size decreases with decreasing Reynolds number and increasing Weber number. Three different modes of bubble formation are observed: a spraying mode obtained at low airflow rate and high applied voltage, a dripping mode observed at high flow rate and low applied voltage, and a mixed spraying−dripping mode.