AN ANALYTICAL MODEL FOR EXPANSION AND DEPOSITION OF CHARGED SPRAY DROPS

An analytical model is developed accounting for the expansion of an electrically charged spray, further to its temporal deposit ion on a target . The model ern­ ploys the Gauss law to determine the electric field that arises from the charged spray, bounded by an earthed control surface. This, in turn, provides the electli.e force field acting on the spray drops, leading to the spray transient c.oncentration . The c.oncen­ tration field, in combination with the electric field, results in a theoretic.al relat ion, which represents a deposition time constant as an index of the d1arg­ ing effect . The dependence of the time constant on a drop electli.c charge approves the positive role of a charged spray on improvement of the deposit ion within a shorter time interval . Although an increase in the spray concent ration, as well as the use of larger drops, also enhance the deposition, this en­ hancement indirectly stems from an increase in the drop charge, which occurs due to those fa.c.,t.ors. The results obtained from the model are also verified against the direct solution of the Poisson equation.