Finite-element analysis of space-charge suppression of electrostatic-induction spray charging

A finite-element analysis of the space-charge suppression encountered during the electrostatic-induction spray-charging process is presented. This paper provides a theoretical framework in support of the experimental studies reported elsewhere of the space-charge-limiting barriers of nozzle design. Poisson's equation is solved using a finite-element axisymmetric model consisting of 3704 triangular elements and 1946 nodes for various placements of nearby earthed surfaces. Plots of constant potential surfaces in and around the dielectric embedded-electrode charging nozzle are presented. The axial droplet-charging potential gradient at the tip of the liquid jet (along the axis of symmetry) depends upon both the positive induction electrode potential and upon the presence, and substantially upon the spatial extent of the negatively charged cloud of dispensed droplets.