Ignition and combustion of air/fuel mixture in a long tube induced by microwave subcritical streamer discharge

Abstract

There have been consistent efforts in developing more efficient combustion for propulsion systems. Ignition and combustion control using cold and non-thermal plasma in microwave discharges have become a major topic of interest. In this study, a microwave subcritical streamer discharge is used to initiate ignition and combustion of premixed air/fuel mixture in a long cylindrical tube. The streamer discharge is arising on the internal surface of the dielectric tube using a passive vibrator in a single pulse regime at atmospheric pressure and temperature. The propagation speed of the combustion front in the quartz cylindrical tube filled by the air/propane mixture is analyzed experimentally and numerically. The streamer discharge creating a multitude of ignition points provides practically instantaneous ignition of the mixture in the entire volume. The speed of streamer induced combustion front has been shown to be higher compared to that initiated by a spark. Increasing the length of streamer discharge leads to increasing the flame propagation speed. The combustion efficiency has also been shown to be higher when using the microwave streamer ignition.

Experimental Study of Air Breakdown Induced by Subcritical Streamer Microwave Discharge

“…Characteristic feature of the streamer discharge is the formation of a spatially spreading structure [17]. Streamer discharge has a complicated composition of thin plasma filaments in the integrated photographs with exposure times which is larger than duration of microwave pulse (Figure 2).…”

“…Various types of plasma discharges have shown promising characteristics in different applications including flow control in aerodynamics [5][6][7], ignition and combustion in propulsion engineering [8][9][10][11][12][13], stabilization of flames [14][15][16][17]. Characteristic propane ignition and combustion times in the supersonic flow with Mach number 2 could be decreased up to factor 2-5 by plasma-assisted combustion [8,9].…”

Multi-point ignition of air/fuel mixture by the initiated subcritical streamer discharge

“…Despite the results achieved and the level of understanding of the structure of emerging flows, the diffraction of shock waves and the organization of shock-wave and detonation processes in propulsion systems remain the subjects of theoretical, experimental and numerical studies [36][37][38][39][40][41]. Previous experimental and numerical investigation of ignition and combustion of fuel/air mixtures have demonstrated a great potential and promising characteristics of the microwave streamer discharge and their ability to ignite lean fuel/air mixtures in long tube [42,43], and sub-and supersonic flows [44,45].…”