Control of oblique shock wave/boundary layer interactions using plasma actuators

Localized arc filament plasma actuators (LAFPAs) are used for shock wave/boundary layer interaction induced separation control in a Mach 2.3 flow. The boundary layer is fully turbulent with a Reynolds number based on the incompressible momentum thickness of 22,000 and shape factor of 1.37, and the impinging shock wave is generated by a 10 degrees compression ramp. The LAFPAs are observed to have significant control authority over the interaction. The main effect is the displacement of the reflected shock and most of the interaction region upstream by approximately one boundary layer thickness (similar to 5 mm). The initial goal of the control was to manipulate the low-frequency (St similar to 0.03) unsteadiness associated with the interaction region. A detailed investigation of the effect of actuator placement, frequency, and duty cycle on the control authority indicates the actuators' primary control mechanism is not the manipulation of low-frequency unsteadiness. Detailed measurements and analysis indicate that a modification to the boundary layer through heat addition by the actuators is the control mechanism, despite the extremely small power input of the actuators.