Acoustic Testing of the dielectric barrier discharge (DBD) plasma actuator

Abstract

The dielectric barrier discharge (DBD) plasma actuator has been shown to be effective for flow control. Much remains unanswered, however, as to how the actuator couples momentum into air. A better understanding of the coupling mechanism is crucial to determining the performance limitation of the actuator and the breadth of applications to which it can be applied. The small physical volume and transient nature of the actuator plasma make it difficult to make direct measurements. In previous work we have investigated the plasma actuator’s optical emission signature extensively. In this work, we measure and analyze the acoustic emissions, both directional characteristics and waveform, from an actuator in an attempt to shed light on the coupling process. Two sets of measurements were made, each using a different apparatus. Both sets of tests reveal that the actuator adds a larger amount of momentum into the air during the negative-going half of the AC voltage cycle and a smaller amount on the other half of the cycle. It was observed that the acoustic pattern produced is a radiation pattern characteristic of a coherentlydriven system. The results suggest that compressibility effects may play a role in the momentum coupling.