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.

由于电极结构的不对称性和介电层的存在，由表面介电势垒注入 (SDBI) 致动器产生的 EHD 壁射流的机制仍有待阐明。考虑电荷注入和解离机理以及表面电荷积累效应，建立基于有限元法的通用EHD壁射流模型，探索方波信号下的电场和流场耦合特性。模拟结果表明，在电极尖端形成同质电荷区，而在上表面区域形成异质电荷区。注入的电荷随着流场向下游移动，由于迁移和积累而附着在电介质表面上。相反电荷的运动有助于涡旋的形成过程，其轨迹与涡旋演化路径一致。对于方波的每一个半周期，速度变化规律和电流变化规律都具有先急剧上升后呈指数下降的特征。