Investigation of pulsed plasma jet for supersonic flow control

A high-frequency ($\approx $5 kHz) and high velocity-amplitude (250 -- 300 m/s) pulsed plasma jet actuator is currently undergoing development in our laboratory for application in supersonic flow control. The actuator is composed of an array of three jets that are pitched and skewed to form three pulsed streamwise vortices at high-bandwidth. The actuator has been used to control the separation shock motion in a Mach 3 compression-ramp shock / boundary layer interaction. Planar laser scattering visualization of a seeded CO$_{2}$ fog was performed in planes parallel to the wall 0.012954 to study the disturbance caused by the actuator. Imaging was performed at distances of 0.25$\delta $, 0.5$\delta \quad {\rm g}$ and 0.9$\delta \quad {\rm g}$ above the wall, where $\delta $ is the boundary layer thickness. It was found that individual pulsed plasmajet causes considerable heating of the surrounding fluid, which is seen till a distance of 15 jet diameters downstream of the actuator and 0.5$\delta $ from the wall. The disturbance is convected at a velocity which is very close to the local velocity of the unforced boundary layer. Particle image velocimetry will be performed in order to obtain quantitative information of the flowfield around the disturbance with attention to the magnitude of the longitudinal vorticity that is generated by the pulsed plasma jet.