Effects of combustion instability on flame macrostructures and NO_x emissions were conducted experimentally in a model gas turbine combustor. Two variables of the CH₄ flame were investigated—the flow rate and the equivalence ratio. Results indicate that flame macrostructure changes when the equivalence ratio increases from 0.50 to 1.00, the average total length of flame front firstly decreases from 105 to 75 mm, and then increases to 110 mm. While the average length of flame root decreases from 25 to 5 mm. The appearance of the flame front evolves from a “M” shape to a reversed “V” shape, but the appearance of the flame root changes from elongated V shape to a flatted V shape. The envelop diagram of different combustion instability signifies that there are mode shifting of flame‐acoustic interactions in the combustion chamber. Under instability conditions, the temperature and velocity distribution of the flame front or flame root affects the NO_x emissions. Along the radial direction, the peak temperature in the inner recirculation region and the outer recirculation region drops. This article explored the dynamic characteristics of lean‐premixed flames under combustion instability, which could be instructive to the designing of stable and clean combustors in industrial gas turbines.

中文翻译：

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燃烧不稳定条件下稀薄预混火焰的宏观结构和NOx排放演变特征

火焰宏观结构和NO的燃烧不稳定性的影响_X是在一个模型气体涡轮机燃烧器实验中进行排放。CH _4的两个变量研究了火焰-流量和当量比。结果表明，当当量比从0.50增加到1.00时，火焰宏观结构发生变化，火焰前锋的平均总长度从105 mm减小到75 mm，然后增加到110 mm。而火焰根的平均长度从25毫米减少到5毫米。火焰前缘的外观从“ M”形演变为反向的“ V”形，但火焰根的外观从拉长的V形变为平坦的V形。不同燃烧不稳定性的包络图表明，燃烧室内火焰声相互作用的模式发生了变化。在不稳定条件下，火焰前沿或火焰根的温度和速度分布会影响NO _x排放。沿着径向方向，内部再循环区域和外部再循环区域中的峰值温度下降。本文探讨了燃烧不稳定性下稀薄预混火焰的动态特性，这对设计工业燃气轮机中稳定，清洁的燃烧器具有指导意义。