Experimental investigation of electrostatically charged liquid hydrocarbon sprays for power generation applications

Electrospray technology has caused a veritable revolution in the field of analytic chemistry but its potential for applications relating to power generation has not been thoroughly investigated. Liquid fuel injection is typically driven by significant pressure differences and dispersion relies almost exclusively to phenomena related to fuel inertia, even for novel ideas like high pressure gasoline direct injection (GDI). In this paper, we offer an experimental investigation of the extent to which inertia! and electrostatic phenomena can be combined for liquid hydrocarbon spray injection. A GDI injector was modified so that the liquid fuel was charged and the effect of electric fields on spray steering and atomization was studied, with a particular emphasis on the determination of the relative importance of inertial and electrostatic forces for varying conditions of injector operation. Spray penetration and cone angle were measured using laser light Mie scattering and digital imaging. The acquired images scanned the transient injection, over a range of fuel pressures, with either 0 or 3 kV voltage applied to the injector tip. Results showed that the electric fields had little effect above an injection pressure of 10 bar, at cold ambient conditions. However below this level, it was possible to significantly influence spray dispersion and atomization through electrostatic effects. Also, measurements of the charge transferred to the gasoline spray are reported.