The results of experimental study of plasma-based mixing, ignition and flameholding in a supersonic model combustor are presented in the paper. The model combustor has a length of 600 mm and cross section of 72 mm width and 60 mm height. The fuel is directly injected into supersonic airflow (Mach number M =2, static pressure P _st =160–250 Torr) through wall orifices. Two series of tests are focused on flameholding and mixing correspondingly. In the first series, the near-surface quasi-DC electrical discharge is generated by flush-mounted electrodes at electrical power deposition of W _pl =3–24 kW. The scope includes parametric study of ignition and flame front dynamics, and comparison of three schemes of plasma generation: the first and the second layouts examine the location of plasma generators upstream and downstream from the fuel injectors. The third pattern follows a novel approach of combined mixing/ignition technique, where the electrical discharge distributes along the fuel jet. The last pattern demonstrates a significant advantage in terms of flameholding limit. In the second series of tests, a long discharge of submicrosecond duration is generated across the flow and along the fuel jet. A gasdynamic instability of thermal cavity developed after a deposition of high-power density in a thin plasma filament promotes the air–fuel mixing. The technique studied in this work has weighty potential for high-speed combustion applications, including cold start/restart of scramjet engines and support of transition regime in dual-mode scramjet and at off-design operation.

The use of a low energy, high peak intensity (>100 TW/cm²) femtosecond laser pulse is investigated for guiding and control of a sub-microsecond high voltage discharge. Study of the laser induced plasma channel and measurements of the field required for breakdown in air and nitrogen at atmospheric pressure are presented. Direct imaging of the dynamics of the discharge breakdown shows effective laser guiding. The effectiveness of laser guiding is shown to be critically dependent on the laser focusing geometry, timing, and location relative to the electrodes.

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.

The arc discharge in magnetic field is one of the promising methods to intensify the kinematic transport in various systems. In this work, a detailed study of the flow arising in ambient air during the movement of a pulsed arc in external magnetic field was done. The study was performed using PIV and shadow flow visualization in parallel with the numerical modeling in a 2D MHD approach. The flow evolution during the electric current pulse was analyzed based on the vorticity generation equation. The flow relaxation after the current termination is considered, indicating a significant reduction of the gas velocity after the current termination due to rarefaction waves propagation. The typical flow structure remaining after the MHD interaction is a toroidal vortex with velocity magnitude up to 0.4 of the maximum arc movement velocity during the pulse.

Experimental and computational analyses of jet formation at the boundary of a decaying pulse discharge in an ambient quiescent air at 1 atm are presented. High velocity jets are observed attributed to the channel curvature set during the initial breakdown phase. The general convex-to-concave jet direction is explained, and the mechanisms of jets formation are discussed.