A physical insight into electrospray process in cone-jet mode: Role of operating parameters

Highlights: • A two-phase numerical simulation on electrospray in cone-jet mode is proposed. • Thorough charge conservation and CSF-based VOF tracking models are used. • Cone-jet evolution illustrates existence of onset voltage and minimum flow rate. • Charge relaxation reveals accumulation in buffer layer of liquid-gas interface. • Vortex pattern is drastically affected by flow rate rather than electric potential. - Abstract: This article investigates the formation of cone-jet structure in an electrospray process based on a two-phase numerical simulation. The numerical approach takes account of the coupled governing equations of fluid flow and electrostatics in conjunction with the charge conservation equation and a VOF interface tracking method on the basis of a CSF model. The temporal and spatial evolutions of the cone-jet mode are examined in connection with the operating parameters, i.e. liquid flow rate and electric potential. Under the influence of these parameters, this study elucidates the physical aspects of the geometrical growth and extension along with the electric charge dispersion within the cone-jet structure. Furthermore, the flow patterns developed in the two-phase flow are studied revealing how orderly the operating parameters can alter the flow configuration. The results are compared with experimental data indicating good agreements, which, in turn, confirm the effectiveness of the simulation methodology concerning the electrospray phenomenon.