Visualization of Supersonic Flow in a Channel with an Obstacle by High-speed Shadow Imaging, Pulsed Discharge and Numerical Simulation

In a supersonic flow in a shock tube chamber, a pulsed volume discharge with preionization by ultraviolet radiation from plasma sheets is realized. An obstacle with dimensions of 2 mm ? 48 mm ? 6 mm, installed on the lower plasma sheet across the flow in the discharge chamber, leads to structural changes in the flow and, accordingly, the discharge localization. As a result of the localization of the discharge energy, a complex unsteady gas-dynamic flow is formed, containing discontinuities and inhomogeneities of various types. To visualize the flow, registration of the glow field of a submicrosecond discharge in the flow is used; high-speed shadow shooting with a frequency of 150 thousand frames per second for 14 ms after the initiation of a discharge in an inhomogeneous flow behind the shock wave. Additional information about the flow under study was obtained by numerical simulation based on the Navier-Stokes equations. Numerical data are presented in the form of gas-dynamic quantities distributions, including the modulus of the density gradient, at various stages of the process. A comparison is made between the calculated and experimental shadow images of the flow formed as a result of the discharge energy input; the energy input in the numerical calculation was carried out in accordance with the density field.