Mechanism of Vorticity Generation in Plasma Streamwise Vortex Generators

An experimental investigation into the mechanism of streamwise vorticity generation in an array of plasma streamwise vortex generators is presented. The array is flush mounted to a flat plate on which a nominally zero pressure gradient turbulent boundary layer develops upstream. The investigation is focused on characterization of the influence of freestream velocity, applied peak-to-peak voltage, length of the active electrode, and spanwise interelectrode spacing on streamwise vorticity generation. It is shown that the actuator creates wall-normal vorticity and reorients it into the streamwise direction. In addition, spanwise boundary-layer vorticity is reoriented into the streamwise direction. Scaling relations based on the vorticity transport equation are obtained and experimentally validated. These provide guidance for optimizing the actuators for particular flow control applications.