Non-thermal gliding arc discharge assisted turbulent combustion (up to 80 kW) at extended conditions: phenomenological analysis

Abstract

ABSTRACT Plasma assisted combustion has been proposed as an efficient technique to enhance combustion, especially under the extreme conditions. For shedding light on the interactions between plasma and turbulent flame at extended conditions, a burner design with integrated electrodes was used to couple a non-thermal gliding arc (GA) discharge to a turbulent flame. The morphology and dynamic behaviors of the GA assisted flame under extended flow rates and gas temperatures were investigated by high-speed video imaging. It is found that two distinct types of flame (named as Flame A and Flame B) can be sustained by the GA discharge depending on the local flow conditions. Flame A was sustained by the GA on stable anchor points, while Flame B moved together with the thin plasma volume of the gliding arc, behaving as an unstable flame. When the fed air gas temperature was increased, Flame A became more stable while Flame B became fragile and extinguished easily. Furthermore, the phenomenological findings under different flow conditions imply typical four flame types for the GA discharge assisted combustion system, including the self-sustained flame at relatively low Reynolds number (Re), the GA sustained stable flame at moderate Re number, the GA sustained unstable flame and the GA assisted auto-ignited and propagating flame at relatively large Re number. In all, the GA discharge seems to provide various effects on combustion depending on the overall turbulence as well as the local equivalence ratio, the gas temperature, etc.