甲烷/空气预混旋流火焰回火实验与模拟研究

Experimental and Numerical Study on the Flashback of Methane/Air Premixed Swirl Flame

回火是贫燃预混低污染燃烧室中重要的燃烧不稳定问题之一。本文通过实验结合大涡模拟对钝体旋流燃烧器甲烷/空气预混旋流火焰回火过程进行研究。结果表明,在低湍流(雷诺数Re=4000)和高旋流(旋流数S=1.3)条件下,上游火焰传播由火舌引导的回火模式主导,火舌围绕中心钝体壁面以几乎恒定的回火速度向上游传播,在此过程中火焰–流动相互作用主要发生在火舌前侧。在火焰参考系下,火舌上游的流动偏转主要受径向压力梯度、科氏力以及离心力的影响。

Flame flashback is one of the important combustion instability problems in lean premixed low-pollution combustor.In this paper,the flashback of methane/air premixed swirl flame in a bluff-body swirl burner is investigated with experiments and large eddy simulation.The results show that for low-turbulence(Reynolds number Re=4000)and high-swirl conditions(swirl number S=1.3),the upstream fame propagation is dominated by the fame tongue leading fashback mode.The swirling flame propagates upstream around the central bluff-body wall at almost constant flashback speed,during which the flame-flow interaction mainly occurs in the leading side of the fame tongue.In the flame reference frame,the flow deflection upstream of the fame tongue is mainly affected by the radial pressure gradient,Coriolis force and centrifugal force.