Properties of liquid jet induced by electrohydrodynamic pumping in dielectric liquids

Liquid jet phenomena induced by electrohydrodynamical (EHD) pumping were investigated in isothermal dielectric liquids without direct charge injection at a metal/liquid interface. A pseudo-doughnut to plane electrode system was used to generate an EHD liquid jet, and the liquid jet properties were measured using four different dielectric liquids (which are referred to as DBDN, BCRA, Tr-Oil, and FS-Oil in this paper). The maximum velocity and pumping pressure achieved were 1.5 m/s and 5.5 kPa, respectively, at an applied voltage of 23 kV with approximately 2.5 W of electrical power consumption in BCRA. It is considered that this liquid jet is due to pure conduction pumping. This mechanism is associated with heterocharge layers near the electrodes which are based on the process of dissociation and recombination of the electrolytic species. Furthermore, to obtain high directivity of the liquid jet, two special nozzles (herein referred to as a normal nozzle and spiral nozzle) were designed. A highly directed liquid jet was obtained using the spiral nozzle. In this case, the flow pattern was of a spiral structure. It is considered that this spiral jet is produced by both the Coanda effect and the nozzle shape (conical hole). (C) 2002 Scripta Technica.