Nanosecond Plasma Enhanced H2/O2/N2 Premixed Flat Flames

摘要

The effect of nanosecond pulsed plasma discharges on a laminar, lean ( = 0.5) premixed H2/O2/N2 flame is studied at low pressure (25 torr), using a novel plasma-flame facility, non-intrusive laser diagnostics, and high-fidelity numerical simulations. Spatially-resolved quantitative OH mole fraction and temperature measurements are performed with and without a burst of 200 nanosecond discharge pulses using laser-induced fluorescence. Measured temperatures increase by approximately 20% in both the pre-heat and post-flame zones with the use of the plasma discharge. In addition, OH mole fractions increase by 100 - 500% in the preheat zone and an average increase of 40% in the post-flame gases. Simulations are conducted with a one-dimensional, multi-scale, pulsed- discharge model with detailed plasma-combustion kinetics to develop additional insight into the complex plasma and flame interactions. Good agreement between measured and predicted OH and temperature profiles provides confidence in the model framework. The reduced electric field, E/N, during each pulse varies inversely with number density. A significant portion of the input energy is expended to electron impact ionization in the high temperature regions downstream of the flame because of high E/N in this region (700-1000 Td).