Synopsis of experimentally determined effects of electrostatic charge on gasoline sprays

The effects of applying electrostatic charge to gasoline fuel sprays from a gasoline direct injection (GDI) injector have been investigated. The injector was modified by the addition of an electrically isolated electrode installed on its tip. The morphology of electrostatically charged and non-charged sprays was characterized using a Mie scattering visualization technique, Fraunhofer diffraction measurements of droplet size, and particle imaging velocimetry (PIV) measurements of the velocity field. The PIV measurements showed that the electrostatic charging of the sprays enhanced the vortical motion of the droplets and produced empty pockets within the spray. Furthermore, the charged sprays penetrated further and were wider than the non-charged sprays. The results of the PIV measurements were complemented by Fraunhofer diffraction (Malvern) measurements, which showed significantly increased consistency of droplet size for the electrostatically charged case. The extent of charging of the fuel sprays was determined with combined measurements of the mass and the charge carried by the sprays. In parallel, the electric field generated by the presence of the charged electrode was computed by numerically solving the Laplace equation at the vicinity of the injector tip. With this data, the relative magnitudes of the electrostatic and inertial forces were compared.