Diffracted shock wave propagation in a pulsed volume discharge plasma

The paper presents the results of experimental and numerical studies of the interaction of a nanosecond combined volume discharge and diffracted shock waves in air at Mach numbers ranging from 2.20 to 4.40. The spatial and temporal characteristics of the discharge were determined by analyzing the current waveforms, photographing the discharge glow, and imaging the discharge radiation with nanosecond resolution. The gasdynamic flow in the test section, which had transparent sidewalls, was visualized using the direct shadowgraph technique and recorded by a high-speed video camera operating at up to 525 000 fps. The experiments demonstrated changes in the dynamics of the shock wave configuration as it moved through the plasma region. Numerical simulations were performed based on the Navier–Stokes equations for viscous compressible gas. The power and dynamics of the energy deposition were varied to compare with the experimental flow patterns. The electrical energy of the discharge converted into heat was estimated to range from 0.12 to 0.20 J for the volumetric region and from 0.23 to 0.35 J for the areas of surface energy input. The obtained results help clarify the mechanism of influence of the pulsed energy deposition on supersonic flow with consideration of relaxation processes in the plasma. In general, the change in shock wave flow resulting from the interaction of shock waves with plasma regions is important when considering ways to control high-speed flows.