This paper is devoted to the experimental investigation of gas-dynamic perturbations of the flow near a DC discharge within the supersonic air flow. In particular, the dependence of the length of the evolving oscillation on the discharge current was determined, and the frequency of periodic oscillations was estimated. The experiments were performed in a pulsed wind tunnel at JIHT RAS with the following flow parameters M = 2, static pressure ~ 200 Torr, and gas temperature T = 170 K. A 30-mm long discharge was initiated in the core of the supersonic flow between two coaxial electrodes. A numerical study of the longitudinal discharge carried along with supersonic flow was also performed in the FlowVision software package. For a current less than 1A, the temperature and voltage dependences on the current were supplemented with those obtained earlier. To obtain the flow perturbations studied in the experiment, three calculations were performed: with k-ε and SST turbulence models and in the absence of the turbulence model. In accordance with results of the calculations, we were able to conclude that the SST model calculation matched the experimental data best: the shock waves before the discharge were visible, and the flow separation area was not visible in the Schlieren images.