Discharge characteristics of a gliding arc discharge in a supersonic jet air flow

Abstract

Whereas discharge characteristics of a gliding arc have previously been investigated in a low-speed subsonic flow without considering the effect of shock waves and extremely high turbulence, we here studied an important physical feature of the gliding arc in a supersonic flow that generates complex shock waves and extremely high turbulence. The gliding arc in a 1.2 Mach supersonic jet air flow is investigated by high-speed imaging, schlieren imaging, electrical measurements, and the large eddy simulation. The experimental results show that high-repetition transitions between the spark-type discharges and the glow-type discharge with a frequency of 1.4–2.1 MHz can be observed in the supersonic flow after the gliding arc is generated between the narrowest gap of knife-shaped electrodes, whereas the similar phenomena are invisible in a low-speed subsonic flow. It can be recognized that the high-repetition transitions occur in the region with complex structures of shock waves and expansion waves. The large velocity/density gradient generated by the complex wave structures and the small-scale vortices produced by the strong turbulence is located near the position where the high-repetition transitions occur. The high-repetition transitions between the spark-type discharges and the glow-type discharges are found to be mainly caused by the combined effects of the strong turbulent eddy transportation in the supersonic flow and the drastic change in the flow properties across the shock wave, shedding light on the mechanism of the high-repetition discharge transitions of the gliding arc in a supersonic flow.

Characteristics of Gliding Arc Plasma and Its Application in Swirl Flame Static Instability Control

“…Correspondingly, the ordinary discharge, which was characterized by a long duration and an amplitude of hundreds of milliamperes in the currents (like the currents in Figure 5a), was recognized as a glow-type discharge. The experimental result was in accordance with [27,29].…”

“…Many studies have confirmed that the air flow rates have a great influence on gliding arc plasma [26,27]. In this experiment, the current, voltage, and power waveforms were measured with different flow rates.…”

Atmospheric pressure pulsed modulated arc discharge plasma

“…The improvement type refers to adding new techniques for existing thermal plasma, such as realizing a warm arc or adding a highfrequency source. In this solution, Czernichowski et al [15] promoted the concept of a sliding arc, and then Sun et al [16], Lu et al [17], Zhu et al [18], Feng et al [19] and others applied it to a variety of electrodes, such as blade electrodes, rotating electrodes, Raval electrodes and so on, and explored the combination of sliding arc and other devices. This type of method is usually applied to some endothermic reaction applications (such as fuel reforming), and its efficiency is usually about 50% (the efficiency is defined as the ratio of the reaction enthalpy and actual energy expenses).…”