Experimental investigations of induced flow by DBD plasma actuators with fine structure electrodes

Abstract

Dielectric barrier discharge plasma actuators (DBD-PAs) have been developed for active flow control devices that do not contain mechanical moving parts. In this study, flow properties induced by DBD-PAs with fine structure exposed electrodes were investigated in experiment to accelerate the induced flow. We prepared the following four types of test actuators: (1) normal-type, with the conventional type of exposed electrode, (2) span-type, with fine exposed electrode of a width of 0.1 mm, (3) stream-type, with slot-type exposed electrode, into which many 0.15 by 1 mm slots were cut, and (4) porous-type, with porous-type exposed electrode, into which many holes of diameter 0.15 mm were cut. Analyzing the velocity distribution of the induced jet using particle image velocimetry, we found that at Vp-p = 5-7 kV, the velocity of the induced jet was increased for span-type and stream-type actuators, when compared with normal-type actuator. The largest increase of velocity was about 20% at 20 mm downstream from the electrode. In relation to the mechanism of the acceleration, we found that a dielectric barrier discharge (DBD) is generated not only at the downstream edge, but also at the upstream edge. By the Schlieren flow visualization, it could be seen that the DBD generated in the downstream direction produced an induced jet in the downstream direction as normal. However, the DBD generated in the upstream direction was found to have the effect of producing an induced jet in both the downstream and the upstream directions. In other words, it was qualitatively shown that the jet that was induced by the DBD generated on the upstream side of the fine exposed electrodes adds to the induced jet in the downstream direction, and as a result, the velocity of the downstream direction induced jet increases.

Keywords

• dielectric barrier discharge plasma actuator
• flow control
• piv measurement
• fine structure electrode