环形燃烧室周向点火机理基础研究进展

Progress on light-round ignition dynamics in annular combustor

先进航空发动机普遍采用环形燃烧室结构,其周向点火联焰机理对发动机点火可靠性具有重要研究价值。由于实验室尺度模型实验成本低、测量精度高,已经逐渐成为实验研究环形燃烧室点火机理的重要途径。本文介绍了国内外几种典型的实验室尺度环形燃烧室模型及其相关研究,包括法国巴黎中央理工大学EM2C实验室的MICCA燃烧室模型;剑桥大学的预混/非预混环形燃烧室模型;慕尼黑工业大学的缩比燃气轮机环形燃烧室模型;浙江大学的环形燃烧室和涡轮耦合的TurboCombo模型。环形燃烧室周向点火过程一般分为3个阶段:(1)初始火核的形成;(2)火核扩张发展,在点火针附近喷嘴处形成单个稳定的旋流火焰;(3)火焰沿周向传播,依次点燃全部喷嘴后稳定燃烧。影响周向点火联焰过程的因素众多,机理复杂,已有的实验和数值计算对当量比、点火模式、热功率、流速、喷嘴间距等因素影响下的点火、熄火、火焰传播模式、周向点火时间等特征规律进行了丰富的研究。近年来,在环形燃烧室模型上也逐渐开展了气液两相喷雾燃烧的相关研究。同时,高时空分辨率的先进激光诊断方法的引入也将进一步推动点火机理的更深入研究。

Annular combustors are generally applied in aero-engines.Study on light-round ignition dynamics of annular combustors is important for ignition reliability.Laboratory-scale mo-dels have become a feasible way to investigate the ignition mechanism of annular combustors due to its low economic cost and high precision.Several typical laboratory-scale annular combustors and related experiments are reviewed,including the annular combustor MICCA from EM2C in France,the premixed or non-premixed annular combustor made by Cambridge University,the annular combustor model referred from an industrial gas turbine in Technical University Munich,and the annular combustor TurboCombo with the coupling of the combustor and the turbine interaction made by Zhejiang University.The ignition process can be generally divided into three phases:(1)the formation of a flame kernel in a flammable mixture around the igniter;(2)the kernel expands and grows to be a swirling flame,which is stabilized and anchored upon the adjacent burner;(3)the propagation of the flame(light-round),which successively igniting all the burners and then reaching to steady state.The factors influencing the light-round process are quite complicated.Previous experimental and numerical investigations focus on the equivalence ratio,ignition mode,thermal power,bulk velocity,spacing between burners and so on,which influence the characteristics of the ignition,flameout,flame propagation mode and light-round time in the annular combustor.Recently,the spray combustion is also studied in the similar models.Meanwhile,the application of advanced laser diagnostics with high resolution would promote the understanding of the light-round mechanism.