PUMPING, SPRAYING, AND MIXING OF FLUIDS BY ELECTRIC-FIELDS

The mechanism of electrostatic spraying of insulating fluids, such as air or organic solvents, into relatively conductive fluids, such as wa ter, is investigated in this work. Experiments with air sprayed into w ater through an electrified capillary showed that the pressure inside the capillary increases, reaches a maximum, and then decreases as the applied voltage is increased. The initial pressure increase is due to the electric stress on the fluid interface, while the decrease is due to the Coulombic electrohydrodynamic flow generated near the end of th e capillary. It is shown that electric fields can cause simultaneous p umping, spraying, and mixing of fluids. This phenomenon is demonstrate d for air and kerosene in water.