MDBD等离子体激励器诱导流场耦合作用机理

Mechanism of coupling effect of flow field induced by MDBD actuator

为揭示多级介质阻挡放电(multi dielectric barrier discharge,MDBD)等离子体激励器诱导流场耦合机理,采用等离子体体积力模型与Navier-Stokes(N-S)方程结合的数值模拟方法,开展静止大气条件下4组激励器并联的MDBD诱导流场特性研究。结果表明:定常激励时,MDBD可以有效提高诱导射流速度与厚度、拓宽激励区域。非定常激励时,MDBD每级激励器对诱导涡起到持续的动量注入作用,延缓其耗散,并增强诱导涡的对流与掺混能力。激励频率对MDBD性能影响较大,激励频率f=20 Hz时,DBD诱导脉冲射流形成的低压区域对诱导涡起“拖拽”作用,使其加速向壁面靠近;f=50 Hz时,诱导涡出现融合现象,旋涡强度增强,对流速度提高,涡核高度降低;f=200 Hz时,诱导涡之间相互作用减弱,呈现为一组“涡簇”向激励器下游移动。

In order to reveal the mechanism of the coupling effect of the flow field induced by the multi dielectric barrier discharge(MDBD)actuator,the numerical simulation method based on the combination of the plasma body force model and Navier-Stokes(N-S)equation was employed to study the actuation characteristics of MDBD under the condition of the static atmosphere.The results indicated that,under the condition of steady actuation,the MDBD plasma actuator can effectively increase the induced flow velocity and thickness,and broaden the actuation area.In addition,under the condition of unsteady actuation,each actuator of MDBD provided a continuous momentum injection to the induced vortex,retarded its dissipation process and enhanced its convective and mixing capabilities.The cyclic actuation frequency had a large impact on MDBD performance.When the actuation frequency was f=20 Hz,the lowpressure region formed by the pulse jet accelerated the induced vortex towards the wall of the plate.The phenomenon of the induced vortex fusion was observed at the condition of f=50 Hz,which can enhance the induced vortex strength and velocity,and reduce the height of the induced vortex core.When the actuation frequency was f=200 Hz,the effect between the induced vortices was weakened,which was convected downstream of the actuator as a format of vortex clusters;in this condition,the effect of MDBD was similar to multiple independent SDBD actuators.