Air Interactions of Magnetically Driven Plasma Discharges in Crossflow

Motivated by the use of magneto hydrodynamic devices in fluid dynamic flow control research, the current work experimentally studied the actuation mechanism and the resulting aerodynamic interactions of magnetically driven low-current arc-plasma discharges. The investigation was conducted in the context of boundary layer interactions in low-speed cross flow conditions through the use of a coaxial and a v-shaped geometries. Time-averaged Stereo-PIV data showed that the to roidal region of vorticity induced by the coaxial geometry in quiescent air resulted in the formation of a horseshoe vortex in cross flow. Similarly, the v-shaped actuator resulted in the formation of stream wise vortices. The resulting boundary layers had s-shaped stream wise velocity profiles as measured in the wall-normal direction characteristic for the flow downstream of a conventional vortex generator pair, due to the three-dimensional mixing induced by coherent vortex structures. A simplified model based on intermolecular momentum transfer through collisions is proposed to explain the fundamental discharge-air interactions and the induced flow fields. These results inform the applications of various magnetically driven discharges in the field of aerodynamic flow control.