Characteristics of a Gliding Arc Discharge Under the Influence of a Laminar Premixed Flame

The effect of combustion on a gliding arc (GA) discharge is investigated using simultaneous measurements of current and voltage waveforms, as well as imaging and spectroscopic analysis of plasma and flame luminescence. Attributed to the existence of flame, the breakdown voltage and current peak are reduced and the bright sparks during breakdown are dampened. The intrinsic reason is largely owing to the thermal effect of flame. Electrical breakdown is mainly determined by the reduced electric field strength (
$E/N)$
, which is inversely proportional to temperature. Assuming a constant
$E/N$
for breakdown, the combustion-induced temperature increment gives rise to a reduction of the breakdown voltage. The gas composition seems to have less impact on the breakdown voltage. However, the addition of CH
₄
can induce more radicals (e.g., H atoms) that enhance the intensity of relevant spectral emissions, especially from OH*. Due to the transport of relatively long-lived radicals, the width of the plasma column of the GA discharge is broadened to form a local reaction zone, serving as a flame holder. Interestingly, the plasma channel moves more smoothly as the flame is present. It implies that the flow field is less turbulent owing to combustion.