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ELECTROHYDRODYNAMICS OF ELECTRIFIED LIQUID MENISCUS AND EMITTED JETS—NONEQUILIBRIUM SURFACE PHENOMENA
978
Abstracts
REF ER E NCE S Gan aH n-Calvo, A. M., DaH vila, J. and Barrero, A. (1997) Current and droplet size in the electrospraying of liquids scaling laws. J. Aerosol Sci. 28, 249}275.
ELECTROHYDRODYNAMICS OF ELECTRIFIED LIQUID MENISCUS AND 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$ciently low #ow rates. In this case, the meniscus shape almost coincides with Taylor's cone and the emitted jet is extremely thin. Its diameter is many orders of magnitude smaller than meniscus dimensions, while the jet length is usually comparable with them. These features of the meniscus and jet allow their theoretical description to be derived directly from the basic equations of #uid dynamics and electrodynamics. To do that we use asymptotic expansions in the small parameter which is proportional to the Weber number of the meniscus-jet. the basic equations also take into account nonequilibrium relaxation of the ion distribution in the surface charge layer and the in#uence of surface ions on surface tension (electrocapillary e!ect) at the meniscus-jet surface. In this work asymptotic systems of di!erential equations have been obtained by perturbation methods in the regions of the meniscus, jet, and surrounding gas. The solutions to these equations have been found, matched with each other, and applied to the investigation of the cone-jet mode of electrospray atomization. Using the developed asymptotic approach we have been able: (i) to "nd distributions of electrodynamic and hydrodynamic variables in all regions (the meniscus, jet, and surrounding gas); (ii) to study the sturcture of electrohydrodynamic #ow inside the meniscus and jet; (iii) to determine and analyze the shape of the perturbed meniscus and jet; (iv) to obtain the electric charge and normal electric "eld strength at the surface of the meniscus and jet. These characteristics are of vital importance for the gas-phase ion production by means of the "eld evaporation. It also follows from the developed theory that the non-dimensional current f"I(cKQ/e)\ carried by the jet depends only on the dielectric constant epsilon as f+2(e where c and K are the surface tension coe$cient and electrical conductivity of the liquid, I and Q are the electric current and volume #ow rate of the liquid. This dependence is consistent with the scaling law found experimentally by Fernandez de la Mora and Loscertales (1994) J. Fluid Mech. 260, 155}184.
Abstracts
REF ER E NCE S Gan aH n-Calvo, A. M., DaH vila, J. and Barrero, A. (1997) Current and droplet size in the electrospraying of liquids scaling laws. J. Aerosol Sci. 28, 249}275.
ELECTROHYDRODYNAMICS OF ELECTRIFIED LIQUID MENISCUS AND 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$ciently low #ow rates. In this case, the meniscus shape almost coincides with Taylor's cone and the emitted jet is extremely thin. Its diameter is many orders of magnitude smaller than meniscus dimensions, while the jet length is usually comparable with them. These features of the meniscus and jet allow their theoretical description to be derived directly from the basic equations of #uid dynamics and electrodynamics. To do that we use asymptotic expansions in the small parameter which is proportional to the Weber number of the meniscus-jet. the basic equations also take into account nonequilibrium relaxation of the ion distribution in the surface charge layer and the in#uence of surface ions on surface tension (electrocapillary e!ect) at the meniscus-jet surface. In this work asymptotic systems of di!erential equations have been obtained by perturbation methods in the regions of the meniscus, jet, and surrounding gas. The solutions to these equations have been found, matched with each other, and applied to the investigation of the cone-jet mode of electrospray atomization. Using the developed asymptotic approach we have been able: (i) to "nd distributions of electrodynamic and hydrodynamic variables in all regions (the meniscus, jet, and surrounding gas); (ii) to study the sturcture of electrohydrodynamic #ow inside the meniscus and jet; (iii) to determine and analyze the shape of the perturbed meniscus and jet; (iv) to obtain the electric charge and normal electric "eld strength at the surface of the meniscus and jet. These characteristics are of vital importance for the gas-phase ion production by means of the "eld evaporation. It also follows from the developed theory that the non-dimensional current f"I(cKQ/e)\ carried by the jet depends only on the dielectric constant epsilon as f+2(e where c and K are the surface tension coe$cient and electrical conductivity of the liquid, I and Q are the electric current and volume #ow rate of the liquid. This dependence is consistent with the scaling law found experimentally by Fernandez de la Mora and Loscertales (1994) J. Fluid Mech. 260, 155}184.