AC-augmented dielectric barrier discharge plasma actuators: effects of operating conditions, phase shift, and electrode spacing

Dielectric barrier discharge (DBD) plasma actuators generate an electrohydrodynamic (EHD) force through the ionization and acceleration of charged species. Most active flow control DBD applications are only practical at lower Reynolds numbers, and increasing the momentum injection can extend the practical uses of the technology. Here, we experimentally demonstrate improvement in the performance of a planar DBD actuator by utilizing an AC-augmented (ACA) electrical field in a three-electrode geometry. Time-resolved electrical and optical measurements, velocity profiles, and direct thrust measurements were used to characterize the EHD augmentation. Varying phase shift and E-field strength between the two air-exposed DBD electrodes can accelerate EHD flow and increase EHD forcing by up to ∼40%. At the most favorable conditions, the maximum thrust was 54 mN m−1 when the air-exposed electrodes were out of phase. In-phase operation of the exposed electrodes at high E-field conditions can induce adverse effects and sliding discharge. Mechanistically, the performance improvements in the ACA DBD actuator primarily come from the additional charge pull action by the ACA electrode. The insight into the ACA DBD mechanism allows for the development of multi-stage arrays capable of further increasing EHD forces.