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.

Mechanism of hydrodynamic noise generation in a subsonic flat plate boundary layer by a barrier discharge plasma actuator is described. The origin of the pulsations is an inscintric unsteadiness of the discharge structure caused by wandering of the microdischarges. Statistics of discharge wandering is obtained from discharge light emission. Propagation of the disturbances in a slightly unstable Blasius boundary layer is studied both experimentally and numerically. It is demonstrated that the discharge-induced noise can be modeled as a sum of delta-correlated localized boundary layer forcing events, with each event represented by the region of longitudinal and transversal force. Discharge-induced disturbances in the boundary layer undergo three main stages as they move downstream: streak-like structures in the near field, oblique wave fans, and eventually a plane Tollmien–Shllichting wave. A simple statistical model, describing the dependency of the pulsations power on actuator driving frequency and voltage, is proposed.

The complex unsteady flow in cavities leads to the formation of large-scale disturbances in the shear layer. Natural closed-loop mechanisms provoke a dramatic increase in pressure pulsations and aerodynamic noise. This paper presents the experimental study of pressure fluctuations in closed-loop control in rectangular cavities using plasma dielectric barrier discharge. The flow velocity was 37 m/s, and the Reynolds number based on a cavity depth was approximately 120,000. The discharge ignition near the leading edge of the cavity provoked the shear layer restructuring. It was found that pressure fluctuations with an amplitude of 120 dB occur at frequencies 480 and 820 Hz. Frequency modulation of the discharge at resonant peaks was carried out by changing the phase shift of the power supply. The peak amplitude was reduced or increased by phase shifts from natural disturbances to forced ones. The optimum energy input was 50 W/m. This was three times less than the power consumption of the open-loop mode. The PIV visualization was organized in the phase-locked mode. The pressure spectrum corresponds to the magnitude of coherent structures in the shear layer of the cavity.

The structure of a flow that appears during the motion of a pulsed surface arc discharge in a transverse magnetic field is described. It is shown that the motion of the plasma channel leads to the formation of a toroidal vortex. The typical velocity of gas inflow to the wall in the aerodynamic wake of the arc was 30‒50 m/s and corresponded to the value of up to 40% of the maximum expansion velocity of the gas during the current pulse.

The paper presents results of experimental study of surface MHD arc actuator as vortex generator in boundary layer. The study was held at flow velocities 20 to 50 m/s. The pulsed arc discharge was organized in external magnetic field. The amplitude of current was varied in the range from 8A to 160A, while pulse duration was from 40 μs up to 380 μs. The flow velocity was measured by PIV method. It was found that the increase of pulse duration leads to increase circulation vortex. The destruction of induced vortex was observed at 40 mm downstream from spark gap.