The role of ambient gas in the electrospray cone-jet formation

This article reports on a study into ambient gas's role in forming the electrospray cone-jet mode. The study aims to broaden the current knowledge, which is essentially confined to air as the surrounding medium in the electrospray process. This research is founded on a liquid-gas simulation, including fluid and electrostatic governing equations coupled with charge conservation and volume of fluid (VOF) interface tracking approaches. The application of various ambient gases, i.e., air, oxygen, nitrogen, methane, helium, and hydrogen, has a decisive impact on the cone-jet structure concerning geometrical profiles, which are mainly reflected in the dimensions of the whole cone-jet and the cone alone. The results indicated the altering effects of the ambient gas on equipotential configuration and charge density magnitudes. The flow patterns clarified the role of the gas type in streamlining and vortex creation within the fluid phases. Two validation tests were also performed to compare the simulation results with the experimental charged jet formation and the electrical variation of droplet mean diameter. The results displayed a good agreement supporting the aptness of the model developed.