Combustion performance of plasma-stabilized lean flames in a gas turbine model combustor

Abstract

This work presents an experimental study of the stabilization of lean methane-air flames by nanosecond repetitively pulsed (NRP) discharges. The experimental facility consists of a gas turbine model combustor with a Lean-Premixed-Prevaporized injector. The working pressure is 1 atm. The fuel is injected through two stages, each stabilized by swirl. The main stage consists of a multipoint annular injection. This facility is representative of a single sector of a gas turbine combustion chamber. The NRP discharges significantly extend the lean blow-off limit for a wide range of operating conditions, down to an equivalence ratio of 0.16. Lean flame stabilization is demonstrated for flame thermal powers up to 100 kW, with an electric power of less than 0.2% of the flame thermal power. We also observe plasma-assisted lean flames emiting less NO_X than the leanest stable flames without plasma. Finally, by exploring the application of various pulse patterns instead of applying the discharges continuously at a constant repetition frequency, the plasma-to-flame power ratio required to stabilize a lean flame is decreased to 0.06% and the pollutant emissions can be further decreased.