Gasdynamic Flow Control by Ultrafast Local Heating in a Strongly Nonequilibrium Pulsed Plasma

Abstract

Abstract— The paper presents a review of modern works on gasdynamic flow control using a highly nonequilibrium pulsed plasma. The main attention is paid to the effects based on ultrafast (on the nanosecond time scale for atmospheric pressure) local gas heating, since, at present, the main successes in controlling high-speed flows by means of gas discharges are associated with this thermal mechanism. Attention is paid to the physical mechanisms responsible for the interaction of the discharge with gas flows. The first part of the review outlines the most popular approaches for pulsed energy deposition in plasma aerodynamics: nanosecond surface barrier discharges, pulsed spark discharges, and femto- and nanosecond optical discharges. The mechanisms of ultrafast heating of air at high electric fields realized in these discharges, as well as during the decay of the discharge plasma, are analyzed separately. The second part of the review gives numerous examples of plasma-assisted control of gasdynamic flows. It considers control of the configuration of shock waves in front of a supersonic object, control of its trajectory, control of quasi-stationary separated flows and layers, control of a laminar–turbulent transition, and control of static and dynamic separation of the boundary layer at high angles of attack, as well as issues of the operation of plasma actuators in different weather conditions and the use of plasma for the de-icing of a flying object.

High-Speed Shadowgraphy of the Interaction of an Oblique Shock Wave in a Channel with a Surface Sliding Discharge

“…Low-temperature plasma has been studied because of its significant potential for high speed flow control [1][2][3][4][5][6] and for plasma assisted combustion [7,8] in aerospace science. The effects of different types of electrical discharges on airflow and streamlined bodies are discussed widely during the last three decades [1][2][3][4].…”

“…Low-temperature plasma has been studied because of its significant potential for high speed flow control [1][2][3][4][5][6] and for plasma assisted combustion [7,8] in aerospace science. The effects of different types of electrical discharges on airflow and streamlined bodies are discussed widely during the last three decades [1][2][3][4]. The main advantage of this control is the small actuation time, which makes actuator effective in a wide frequency range for gasdynamic flows control from stationary flows to turbulent and separated flows.…”

“…The main advantage of this control is the small actuation time, which makes actuator effective in a wide frequency range for gasdynamic flows control from stationary flows to turbulent and separated flows. Actuators are used to reduce surface friction, to influence the laminar-turbulent transition, to the position of separation zones and shock waves near the streamlined surface [2][3][4][5][6], to control the ignition of fuels and combustion [4,7].…”

“…The main part of the electrical energy of the discharges in the air goes to the excitation of vibrational and electronic degrees of freedom of molecules [9]. A rather large proportion of electrical energy goes into translational degrees of freedom of gas molecules in the microsecond time interval [2][3][4]. The other part transforms into thermal energy in the process of vibrationaltranslational relaxation within several milliseconds [9].…”

“…The other part transforms into thermal energy in the process of vibrationaltranslational relaxation within several milliseconds [9]. The ion motion plays a key role in the plasma dynamics in the boundary layer and the spatial distribution of input energy release, as discussed in experimental and modeling studies [1,2,4]. Some investigations focused on the shock wave generation in supersonic flow and the plasma control of shock wave-boundary layer interaction [2, 3,5,6].…”