REFERENCES

Gan8 aH n-Calvo, A. M., DaH vila, J. and Barrero, A. (1997) Current and droplet size in the electrospraying of liquidsscaling laws. J. Aerosol Sci. 28, 249}275.

ELECTROHYDRODYNAMICS OF ELECTRIFIED LIQUID MENISCUSAND EMITTED JETS*NONEQUILIBRIUM SURFACE PHENOMENA

Leonid T. Cherney

Institute of Mechanics, Moscow State University, Michurinsky prospect 1, Moscow, Russian Federation

The present work deals with the cone-jet mode of electrospray atomization of liquids at su$ciently low #owrates. In this case, the meniscus shape almost coincides with Taylor's cone and the emitted jet is extremely thin. Itsdiameter is many orders of magnitude smaller than meniscus dimensions, while the jet length is usually comparablewith them. These features of the meniscus and jet allow their theoretical description to be derived directly from thebasic equations of #uid dynamics and electrodynamics. To do that we use asymptotic expansions in the smallparameter which is proportional to the Weber number of the meniscus-jet. the basic equations also take intoaccount nonequilibrium relaxation of the ion distribution in the surface charge layer and the in#uence of surfaceions on surface tension (electrocapillary e!ect) at the meniscus-jet surface.

In this work asymptotic systems of di!erential equations have been obtained by perturbation methods in theregions of the meniscus, jet, and surrounding gas. The solutions to these equations have been found, matched witheach other, and applied to the investigation of the cone-jet mode of electrospray atomization. Using the developedasymptotic approach we have been able:

(i) to "nd distributions of electrodynamic and hydrodynamic variables in all regions (the meniscus, jet, andsurrounding gas);

(ii) to study the sturcture of electrohydrodynamic #ow inside the meniscus and jet;(iii) to determine and analyze the shape of the perturbed meniscus and jet;(iv) to obtain the electric charge and normal electric "eld strength at the surface of the meniscus and jet.

These characteristics are of vital importance for the gas-phase ion production by means of the "eld evaporation.It also follows from the developed theory that the non-dimensional current f"I(cKQ/e)~1@2 carried by the jetdepends only on the dielectric constant epsilon as f+2Je where c and K are the surface tension coe$cient andelectrical conductivity of the liquid, I and Q are the electric current and volume #ow rate of the liquid. Thisdependence is consistent with the scaling law found experimentally by Fernandez de la Mora and Loscertales(1994) J. Fluid Mech. 260, 155}184.

978 Abstracts