SUMMARY

Plasmas are widely used to ignite combustible mixtures. The objective of the present study is to develop a plasma based flame holder for high-speed or very lean combustible mixture flows, like those present in afterburners or very low NOx combustors. Flame stabilization can be achieved either by direct exposure of a flammable mixture to a plasma or by injecting a plasma generated radical jet into a reactant flow. A high frequency (HF) spark discharge was selected for this study. In low velocity combustible mixture flows, flames can be stabilized by applying a HF spark discharge to the reactants. The HF spark was shown to extend the limits of flammability and the flowrate at which combustion could be sustained. To increase the flow velocity at which combustion can be stabilized and to further reduce the electrical power consumption compared to the heat released by the combustion process, a Radical Jet Generator (RJG) was developed. The characteristics of this radical jet and the mechanism by which it supports the flame in the cross flow are being investigated. Preliminary results have demonstrated that it is primarily radicals and not thermal effects that stabilize the combustion process. It is the ultimate goal of this study to develop a more complete understanding of the mechanisms and limitations of this flame stabilization method.