Control of Shock Wave Configuration at M=2 Compression Ramp by Array of Filamentary Plasma*

This experimental study considers the effect of an electric discharge on the flow structure near a 12-20 degree compression ramp in M=2 airflow. The tests were conducted in the supersonic wind tunnel SBR-50 at the University of Notre Dame. Stagnation temperature and pressure were varied in a range of 294-600 K and 1-3 bar, respectively, to attain various Reynolds numbers ranging from 3e5 to 2e6. Surface pressure measurements, schlieren visualization, electric measurements of the discharge parameters, and plasma imaging with a high-speed camera were used to evaluate the plasma control authority on the ramp pressure distribution. The plasma being generated in front of the compression ramp shifts the shock position from the ramp corner to the electrode location, forming a flow separation zone ahead of the ramp. There were found that the pressure on the compression surface reduces linearly with the plasma power, and the ratio of pressure change to the flow pressure is an increasing function of the ratio of plasma power to the flow enthalpy flux. The last parameter is defined as the task-related plasma control efficiency, which ranges from 200 to 300%.