| dc.description.abstract | Electrohydrodynamic (EHD) pumping of single and two-phase media is attractive
for terrestrial and outer space applications since it is non-mechanical, lightweight, and
involves no moving parts. In addition to pure pumping purposes, EHD pumps are also
used for the enhancement of heat transfer, as an increase in mass transport often
translates to an augmentation of the heat transfer. Applications, for example, include
two-phase heat exchangers, heat pipes, and capillary pumping loops.
In this research, EHD induction pumping of liquid film in annular horizontal and
vertical configurations is investigated. A non-dimensional analytical model accounting
for electric shear stress existing only at the liquid/vapor interface is developed for
attraction and repulsion pumping modes. The effects of all involved parameters
including the external load (i.e. pressure gradient) and gravitational force on the nondimensional
interfacial velocity are presented. A non-dimensional stability analysis of
EHD induction pumping of liquid film in a vertical annular configuration in the presence
of external load for repulsion mode is carried out. A general non-dimensional stability criterion is presented. Stability maps are introduced allowing classification of pump
operation as stable or unstable based on the input operating parameters.
An advanced numerical model accounting for the charges induced throughout the
bulk of the fluid due to the temperature gradient for EHD induction pumping of liquid
film in a vertical annular configuration is derived. A non-dimensional parametric study
including the effects of external load is carried out for different entrance temperature
profiles and in the presence of Joule heating.
Finally, a non-dimensional theoretical model is developed to investigate and to
understand the EHD conduction phenomenon in electrode geometries capable of
generating a net flow. It is shown that with minimal drag electrode design, the EHD
conduction phenomenon is capable of providing a net flow. The theoretical model is
further extended to study the effect of EHD conduction phenomenon for a two-phase
flow (i.e. a stratified liquid/ vapor medium). The numerical results presented confirm the
concept of liquid film net flow generation with the EHD conduction mechanism. | en |
