Estudio experimental de la producción de microchorros mediante enfocamiento gaseoso y campos eléctricos

Resumo

The main purpose of this study is the experimental analysis of two of the most used techniques in controlled production of jets, drops, bubbles, and other fluidic structures: electrospray and flow focusing. The flow focusing technique was proposed in 1998 by Gañán-Calvo as a method for droplets production in the micrometer scale. In the basic configuration, the liquid is injected through a submilimeter cilindric capillary located in front of a plate with an orifice (also submilimeter). A gas stream is used to focus the liquid, both liquid and gas, coflowing through the orifice. In this paper, we analize different alternatives to the original configuration such as using of convergent-divergent glass nozzles or several changes to the basic configuration, seeking to improve stability by studing advantages and disadvantages of each of these alternative techniques. In electrospray, a liquid droplet is yielded to strong electric field, which stretchs it until a very thin jet is emmited from its tip. In this paper we analize the behaviour of an eletrified droplet when the applied voltage increases, on one hand, when the stablishment velocity of the electric field is as the same order of magnitude as velocity of the electrical and hydrodinamic phenomena happen inside the liquid and, on the other hand, when this stablishmenet velocity of electric field is higher. The sutdy focuses on the droplet oscillations and the emmited jet produced both by subcritical and supercritical voltage values.