INVESTIGATION ON THE TURBULENT CHARACTERISTICS OF THE JET INDUCED BY A PLASMA ACTUATOR

In order to understand the controlling mechanism of plasma actuator and develop the mathematical model of plasma actuator, the turbulent characteristics of the jet induced by a dielectric barrier discharge (DBD) plasma actuator in quiescent air was studied in a closed chamber using particle image velocimetry (PIV). Here, an asymmetrical DBD plasma actuator was mounted on the plate model. First, measured time-averaged velocity field induced by the DBD plasma actuator indicated that voltage amplitude is an important parameter and could affect the flow characteristics of the induced jet. When the plasma actuator was driven at low voltage, the induced jet was a laminar wall jet. On the other hand, the Reynolds number of induced jet was improved and the shear layer was instability when the plasma actuator was actuated at high voltage. Then the induced jet became a turbulent wall jet. Secondly, the results of transient flow field structure suggested that the induced turbulent wall jet had some coherent structures, such as rolling up vortex and secondary vortex in the near-wall region. And these structures were linked to a dominant frequency of $f_0=109$ Hz. The rolling up vortices had the process of formation, movement, merging and breakdown. Thirdly, the rolling vortex was stretched and collapsed due to the instability of flow field when the plasma actuator was actuated at high voltage. Then turbulence kinetic energy of induced flow filed was increased and the breakdown of rolling vortex was accelerated. The turbulent characteristics of the induced jet could enhance the entrainment effect of plasma actuator between the outside airflow and boundary layer flow, which is very important for flow control applications.