Coupling characteristics of fluid and charge behaviors in an EHD wall jet produced by a surface dielectric barrier injection actuator

Abstract

The mechanism of an EHD wall jet generated by a surface dielectric barrier injection (SDBI) actuator remains to be elucidated due to asymmetry of the electrode structure and existence of the dielectric layer. Taking into account the charge injection and dissociation mechanisms as well as the surface charge accumulation effect, an EHD wall jet model of general applicability based on the finite element method is established to explore the electric field and flow field coupling characteristics under a square wave signal. Simulation results show that a homocharge region is formed at the tip of the electrode while a heterocharge one is built at the upper surface area. Injected charges are attached to the dielectric surface owing to migration and accumulation as they move downstream with the flow field. The motion of opposite charges contributes to the vortex formation process and its trajectory is in line with the vortex evolution path. For each half-cycle of the square wave, the feature of an abrupt increase followed by an exponential decrease applies to both the velocity evolution characteristic and the current variation law.