Effect of Rotating Gliding Arc Plasma on Lean Blow-Off Limit and Flame Structure of Bluff Body and Swirl-Stabilized Premixed Flames

The effect of rotating gliding arc plasma on flame stabilization in a laboratory scale swirl-stabilized plasma-assisted combustor was experimentally investigated. The characteristics of a gliding arc plasma were studied using high-speed camera and simultaneous measurements of current and voltage waveforms. Effects of plasma on the extension of lean blow-off (LBO) limit and the swirl flames structures as well as OH radical distribution have been studied systematically. Results show that the discharge and combustion are coupled together effectively due to the dynamic processes of discharge. When the plasma is activated, the flame structures are drastically changed; oscillating flame and lifted flame convert to stable columnar flame tending to be attached to the plasma column. Besides, the plasma columns can promote OH formation and can produce much more energetic radicals due to the reactions between the discharge, methane and oxygen. The gliding arc plasma can stabilize the flame, provide an additional anchoring mechanism, and significantly extend the LBO limit. The plasma column can provide active radicals and continuous ignition to sustain the flame, and the thermal effect and kinetic effect may occupy the dominant role.