Experimental characterization of an extended electrohydrodynamic cone-jet with a hemispherical nozzle

Abstract

An extended Taylor cone-jet mode is experimentally characterized using a recently introduced hemispherical nozzle. Ethanol is used as the working fluid, and the nozzle produces a much broader range of flow rate and stability of the cone-jet mode. High-resolution images are captured using a high-power light-emitting diode in precise lighting operations to characterize the liquid behavior. Various regimes in the extended cone-jet mode are recognized and mapped in a plane of electro-Weber and Bond numbers. The cone profiles are quantified regarding dimensionless groups, and a related self-similarity is introduced. The cone elongates with the electro-Weber number but retracts as the Bond number increases. The cone and jet diameters are also quantified from the nozzle exit to where the jet begins a transition to instability. It is shown that jet diameter increases with the electro-Weber number powered by 0.75, but it is independent of the Bond number. The meniscus lengths are reported at different electro-Weber and Bond numbers too, and the corresponding correlations are obtained. Finally, jet whipping and spray envelopes are illustrated at various dimensionless numbers, while a wider spray envelope and a dual distribution are recognized at higher electro-Weber numbers.

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