The effect of electrode shape and arrangement on breakup of dielectric liquid jet in electric field

Abstract

In this study, the behavior of dielectric liquid jet in the presence of electric field was analyzed and the effects of electrode geometry and electric field direction on surface wave frequency, jet breakup, and produced droplet characteristics were investigated. When a dielectric liquid jet flows through an electric field, three types of electric forces can be imposed on the flow field: electrophoretic, dielectrophoretic, and electrostriction forces. Flow of liquid jet in gaseous surrounding is affected by electrophoretic and dielectrophoretic forces. Considering the direction of electrophoretic force, applying the electric field in the direction of jet flow thickens the jet by decelerating the flow; nevertheless, inverse field increases the diameter of jet by accumulation of liquid in the downstream region of electrodes. Dielectrophoretic force does not depend on field direction and always increases the diameter of liquid jet. Results showed that breakup length is shortened by electric field and applying a 6 kV electric potential difference can reduce the upper limit of breakup length by 27% in comparison with non-electrified case. Furthermore, the electric field increases the production of round droplets and decreases the number of irregular and sharp-edged droplets. Increase in electric field strength usually leads to reduction in droplet size. Besides, parallel–triangular electrodes in direct field and star–triangular electrodes in inverse field are more effective in the production of round droplets. Although smallest droplets are produced using star–triangular arrangement, parallel–triangular electrodes can produce droplets with more homogeneity in size distribution.