Experimental and Numerical Investigation of a Surface Sliding Discharge in a Supersonic Flow with an Oblique Shock Wave

Abstract

This study presents an experimental and numerical investigation on a surface sliding discharge in a supersonic airflow in the presence of an oblique shock wave. In experiments, flow Mach numbers were 1.20–1.68 in the shock tube combined with the discharge chamber. A single high-voltage 25 kV pulse sustains the plasma; the discharge current has a duration of ~500 ns. A surface sliding discharge is developed as a localized channel in a zone of interaction of an oblique shock wave with a boundary layer on the upper wall of the discharge chamber. The discharge channel acts as a linear source of heat and is at the origin of the induced shock wave. The flow field in the discharge chamber is spatio-temporally surveyed using high-speed shadowgraphy imaging with a frequency of up to 525,000 frames per second. The experiments show that the perturbed flow restored the initial structure after more than 100 μs. Numerical simulation with local energy input into the supersonic flow in a flat channel is carried out on the base of unsteady two-dimensional Navier–Stokes equations. It is determined that the dynamics of an induced shock wave are dependent on the energy input regime and on the flow parameters. The thermal energy release in the discharge channel of 0.22–0.29 J was estimated from a comparison of experimental data and numerical simulations.

Equation of State for Bismuth at High Energy Densities

“…These processes include high-velocity impact [4][5][6][7], interaction with the material of intense laser radiation [8][9][10][11] or particle flows of high power density [12][13][14], and the electrical explosion of conductors [15][16][17]. For numerical simulations of emerging hydrodynamic flows, it is necessary to know the relationships of the thermodynamic characteristics of the medium in the entire range of realizable states [18][19][20][21][22]. Interest in thermodynamic models is also associated, in particular, with the problems of studying the thermoelastic properties of various materials at high pressures [23][24][25][26].…”

Longitudinal DC Discharge in a Supersonic Flow: Numerical Simulation and Experiment

“…The second significant part of the research on plasma aerodynamics is related to the control of the shock-wave structure in a supersonic flow. It is well-known that the pulsed energy input in the discharge is accompanied by the birth of a shock wave and can affect the structure of the external flow [14,15] or the flow in the channel [16]; in this case, the duration of the energy input can be less than a microsecond, and the restoration of the flow structure requires more than 100 µs. When controlling the flow near the compression 2 of 17 surface (in the air intake), the energy input from the plasma actuator can be pulsed [17], or constantly operated, while in both cases, the flow structures change significantly, allowing for optimizing the operation of the air intake in an off-design mode [18].…”