Measurement of Plasma Activity in a 1D Premixed Methane-Air Flame

Abstract

A premixed methane-air flame was produced on a flat flame burner and exposed to electric fields between the burner and a flat grid electrode. Equivalence ratios of 0.8 and 1.0 were tested at electrode supply voltages up to 10 kV. A Langmuir probe was used to record ion current within the flame. The current increased at low potentials but decreased at higher potentials. Maximum ion current was greater for an equivalence ratio of 1.0. The change in ion concentrations was attributed to the ionic wind at low potentials and dissociative recombination at high potentials. NomenclatureI = Current lp = Langmuir probe length ni = Number density of ions q = Elementary charge r = Distance from edge of the burner rp = Langmuir probe radius SLM = Standard Liters per Minute U = Flow velocity Vb = Langmuir probe bias Vss = Electrode supply voltage y = Distance above burner grid ϵ0 = Permittivity of freespace µi = Ion mobility ϕ = Equivalence ratio

Electron Temperature in a Methane-Air Flame under a DC Electric Field

“…This is sufficient to cause a growth in the dissociative recombination rate, such that dissociative recombination can be considered an influential mechanism on flame behavior. Jacobs et al11 observed a growth in the ion density with electric field strength in the premixed flame and partially attributed this to ionic wind effects. This would therefore suggest that the ionic wind and dissociative recombination are a coupled system, with the former driving increases to the latter.…”