Experimental parameter studies of various plasma actuator concepts for active flow control at moderate Reynolds numbers

Plasma actuators are of special interest for Active Flow Control. Plasma actuators have no moving parts and couple their momentum directly into the flow within the boundary layer and direct proximity to the surface. Further advantages of these actuators are the fast response time, the multitude of operational modes, the compact design, and the flexibility in location. However, the relatively low output momentum is a main drawback of plasma actuators. Therefore, most existing applications of plasma actuators are in the range of low Reynolds numbers. In this experimental work, a multitude of various types and designs of plasma actuators was studied. Feasible plasma actuators were identified and optimized for applications at moderate Reynolds numbers. The aim was to move plasma actuator technology towards real applications. In the first phase of this study, more than 50 plasma actuators differing in type and design were tested and compared under uniform conditions in quiescent air. Optimization procedures were found that allowed to improve the output performance, such as a tapered isolator cross section. In the second phase, the impact of various plasma actuators on a fundamental boundary layer flow of a flat plate was studied. The deformation of the baseline boundary layer profile was used as a central parameter in order to compare and evaluate the impact of the plasma actuators on the flow. In the third phase several optimized plasma actuators were deployed around a NACA 0012 airfoil and then tested in a wind tunnel. By actuation at a moderate Reynolds number of Re = 266 000 , the airfoil polar was impacted over the entire range of angles of attack. The generated effect is comparable to the effect of high-lift devices.