Numerical simulation of the cone-jet formation and current generation in electrostatic spray - Modeling as regards space charged droplet effect

A physical model of the electric field induced by charged droplets taking account of the effect of space charged droplet emitted from the tip of cone-jet to the external electric field is proposed. Combining this model with the fluid flow equations and charge conservation equation, the evolution of the cone-jet is simulated. The diameter of droplets emitted from the cone-jet tip and current on cone-jet are predicted at various applied voltages and flow rates. The calculated droplet diameter agrees well with experimental measurement. For low conductivity liquid, the droplet diameter decreases with the increment of applied voltage, but decreases with the reduction of flow rate. The simulation result also indicates that the current on the cone-jet increases linearly with the applied voltage. The electric field induced by charged droplets results in the decrease of the cone angle and the presence of space charged droplets has a non-negligible effect on the operation parameters.