Space charge modelling in a charge injected electrostatic atomiser

In this paper the results of the modelling of viscous flow of a fuel oil in an electrostatic fuel injector are presented. The most important effect is the emission of charge carriers from the charge injection electrode and their spatial distribution in the fluid. For a given geometry of the nozzle, fluid properties inflow rate, and applied potentials at the electrodes, a numerical model has been developed which gives the velocity, hydrodynamic pressure, electric field, electric potential and space charge density distributions. The space charges density that exits the nozzle orifice governs the liquid jet disintegration process. The total current injected into the fuel oil at the injection electrode is divided between the spray current and nozzle body leakage current. Based on the calculated results, it is possible to optimize the nozzle geometry so that the leakage current to total current ratio is minimal.