Experimental investigation on ignition and lean blow-out performance of a multi-sector centrally staged combustor
Improvement on extinction and pollution emission have become one of the most prominent research topics in gas turbine. It is widely recognized that the fuel/air mixture distribution in the recirculation zone is a critical factor in improving lean blow-out (LBO) and ignition. This paper proposed a new low emission scheme with fuel staged centrally and hybrid injector to improve flameout and emission. A relative small amount of fuel enters into central pilot airblast atomizer burner and then atomized by inner swirl air. The remaining majority of fuel is directly injected into vane channels of the primary swirler through a series of holes located on the sidewall of the main stage. Only pilot stage is fueled under ignition and lean flameout condition. The uniformity of fuel/air mixture distribution in the primary zone of the new design decreases NOX emission, meanwhile the fuel air mixture in pilot recirculation zone is locally rich to improve flameout and ignition. Experimental investigation was conducted to compare the new scheme with baseline design of dual-swirler in terms of LBO and ignition characteristics under the same condition in a multi-sector combustor. It is found that the fuel-air ratio of ignition limit and LBO decrease with the reference velocity increasing. The experimental results also show that the new scheme successfully improve lean blow-out and broaden the operation range of the combustor. The experimental results indicated that the centrally staged scheme can widen the operation boundary of the combustor and can provide guidance for design and optimization of combustion chamber.