Shock wave and fully turbulent boundary layer interaction controlled by surface arc plasma actuation

Experiments were performed to examine the control effect of surface arc plasma actuators on a fully turbulent boundary layer interaction over a 26-deg ramp in a supersonic flow. The experiments utilized a non-invasive schlieren measurement device, along with comprehensive statistical processing techniques. Time-resolved schlieren up to 25 kHz were performed for visualization. Root Mean Square (RMS), Fast Fourier Transformation (FFT), and Proper Orthogonal Decomposition (POD) were performed on the schlieren dataset for structure identification in the interaction flow. A discharge is created between an electrode pair located upstream of a ramp to induce significant disturbances in the turbulent boundary layer. The discharge frequencies employed are f_a=0.5, 1, 2, and 5 kHz. The findings indicate that lower excitation frequencies result in a greater instantaneous energy input to the flow field, while the highest cumulative energy is obtained at 5 kHz over time. The separation region inhibited effect is further verified through the RMS of the schlieren intensity. The separation shock weaken is verified through the FFT of the schlieren intensity. The results indicate that perturbations in the fully turbulent boundary layer interaction flow pattern are more effective for separation shock control and separation region inhibition. It is important to appropriately increase the actuation frequency in order to achieve a certain level of control over the reattachment shock. This control effect is dependent on the total energy injected into the flow field rather than a large energy of a single pulse.