Numerical and Experimental Study of the Electrohydrodynamic Atomization of Highly Conducting Liquids, Including Dissipation Effects

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PI: Gamero, ManuelProposal Number: 1604163The goal of the proposed research is to advance theoretical understanding of the fluid dynamics involved in the process known as electrospraying. In this process, often utilized for the manufacturing of well-controlled nanodrops or nanofibers, highly conducting fluids pass through a cone-jet orifice. The proposed research is motivated by recent experimental data showing that energy dissipation is important in electrosprays of highly conducting fluids, especially when nanoscale drops are formed. Manufacturing and nanotechnology have been both identified as areas of National need. The objective of this project is to obtain a fundamental understanding of the electrospraying of highly conducting liquids in the cone-jet mode, with the novel inclusion of thermal effects. The importance of cone-jets of highly conductivity liquids resides in its unique ability for generating uniform sprays of nanodroplets, which are of great interest in manufacturing, spacecraft propulsion and hypervelocity impact research. Although electrospraying in the cone-jet mode has been analyzed on the bases of the leaky dielectric model, recent experimental work has demonstrated that energy dissipation is significant in the highly conductivity, nanometric regime, making it necessary to supplement the mechanical leaky dielectric model with an equation of conservation of energy to resolve the temperature field. Accounting for the actual variation of temperature is important because of the strong temperature dependence of key parameters like viscosity, electrical conductivity, and surface tension. This project will formulate and numerically solve a 2-D, axisymmetric electrohydrodynamic model of the transition region of cone-jets that retains thermal effects, and measure cone-jet characteristics (including the I(Q) law, and the dissipation of energy) with the goal of validating the model. The experimental measurements, in particular the measurement of energy dissipation, must be done in a vacuum environment using a combination of time of flight and retarding potential analyzers. The project includes two broader impact components: fundamental research while promoting teaching, training and learning; and promoting the participation of underrepresented groups. The proposed research will be infused into middle and high school students through: a) a collaboration with the local K-12 school district including the development of activities such as laboratory open-houses and occasional lectures on physics and technological applications associated with the proposed research; and b) summer internships for high school students to work on the NSF project.