The results of experimental and computational studies are considered on a near surface electric discharge effect on supersonic airflow near a 15° compression surface. The tests were performed at Mach number M = 2, stagnation pressure P ₀ = 1–2.8 bar, stagnation temperature T ₀ = 290–600 K, and plasma power W _pl = 6–12 kW. They demonstrated a significant effect of plasma on the flow structure and reduction of static pressure on the compression surface. Transient phenomena were analyzed and it was found that the pressure decrease on the ramp was as fast as t < 0.3 ms. Simulations based on 3D unsteady Navier–Stokes equations with plasma modeled as an array of lengthwise heat sources demonstrated adequacy of such simplifications. Further simulations attempted to find an optimal range of plasma power and position in terms of achievable effect, effectiveness of the method, and response time of the system to the plasma actuation. The electric discharge authority for a fast and effective control of aerodynamic forces in a compression ramp configuration is considered.

This study considers the effect of an electric discharge on the flow structure near a 19.4° compression ramp in Mach-2 supersonic flow. The experiments were conducted in the supersonic wind tunnel SBR-50 at the University of Notre Dame. The 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 5.3 × 10⁵ to 3.4 × 10⁶ based on the distance between the exit of the Mach-2 nozzle and the leading edge of the ramp. Surface pressure measurements, schlieren visualization, discharge voltage and current measurements, 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 shifted the shock position from the ramp corner to the electrode location, forming a flow separation zone ahead of the ramp. It was found that the pressure on the compression surface reduced almost linearly with the plasma power. The ratio of pressure change to flow stagnation pressure was also an increasing function of the ratio of plasma power to enthalpy flux, indicating that the task-related plasma control effectiveness ranged from 17.5 to 25.

This study examined the effect of Reynolds number on plasma-assisted flow control ahead of a compression ramp geometry in Mach-2 supersonic flow. The experiments were conducted in the supersonic wind tunnel SBR-50 at the University of Notre Dame. Stagnation temperature and pressure were varied as T₀=294-500K and P₀=1-3bar to attain Reynolds number ranging from 3.4×10⁵-2.2×10⁶. Ramp pressure measurements, schlieren visualization, and high-speed camera imaging were used for the evaluation of plasma-assisted flow control effects. A linear dependency was found between the ramp pressure change per averaged plasma power and Reynolds number.

An experimental visualization has been carried out to study the dependence of the pressure hill height and the influence zone expanse for flow past rectangular blocks of flat square face and varying length, over a Reynolds number range from 1364 to 4931. It is found that, the pressure hill length and the influence zone expanse decrease with the length to width ratio of the block, up to about L/W = 1, for Reynolds number up to 1586. For higher Reynolds numbers, both H/W and Z/W increase with the model length, till L/W = 1. For L/W more than 1, both H/W and Z/W gradually become independent of L/W. The ratio of Z/H is influenced only marginally by L/W up to 1, and for greater values of L/W, Z/H is almost a constant at all Reynolds numbers of the present study.