Cascade properties of EHD wall jets generated by an actuator with distributed surface-embedded electrode pairs

Abstract

Electrohydrodynamic (EHD) conduction pumps have become a high-quality solution for cooling high-power-density electronic devices in space domains due to their low voltage requirement and simple electrode distribution. Recently, driving environmentally friendly dielectric liquids, such as hydrofluoroethers (HFEs), using a cascaded actuator with distributed surface-embedded electrode pairs has gained attention as an innovative EHD cooling strategy. Previous studies have visualized the acceleration of the jet when it passes through each electrode pair by the PIV technique, and have experimentally verified the effectiveness of cascaded conduction pumps. However, the large time scale of these experimental studies makes it challenging to accurately capture the formation stage of the cascaded jet and thus explore its evolutionary properties. In this paper, a nine-surface embedded electrode pair actuator is modeled based on multiphysics field finite element method simulation. The results show that the four initial vortices above each electrode pair induced by charge migration undergo outer vortex expansion and inner vortex suppression within a short period, accompanied by merging, deflecting, and cascading processes of the localized jets. The vortices above each electrode pair show a consistent distribution pattern with the charge density extremes. The current density increases quasi-linearly over the voltage range of 0.5 kV–5 kV. With the operational number $\beta$ = 2.56 for the conduction pump in this study, the system consistently operates in the ohmic regime.