The aim of this paper is to analyze the self-ignition of a jet flame in hot vitiated cross flow using Large Eddy Simulation with analytically reduced chemistry. A rich premixed ethylene-air mixture ( $$\phi = 1.2$$ ) at 300 K is injected into a hot vitiated crossflow at 1500 K. The simulated reacting flow steady-state was validated against experiments in previous publications and the focus of the present work is the transient self-ignition of the jet. It is shown that spontaneous ignition occurs at very lean mixture fractions in the form of reacting patches in the windward jet mixing layer. These patches grow, laterally wrap the jet and extend into the recirculation region. Chemical explosive mode analysis is performed to identify the chemically active regions that are precursors of the patches undergoing spontaneous ignition. It is shown that the self-ignition occurs at very lean fuel concentrations regions, which are leaner and hotter than the most reactive mixture fraction of the jet and crossflow. This is explained by the fact that the scalar dissipation is significantly lower in these very lean regions. Ultimately, the peak heat release moves toward the richer regions and an autoignition cascade governs the steady state flame anchoring.

中文翻译：

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冷预混乙烯-空气射流在热腐蚀横流中的自燃模拟

本文的目的是使用大涡模拟和分析简化的化学方法来分析热腐蚀交叉流中喷射火焰的自燃。将 300 K 下的丰富的预混乙烯-空气混合物 ($$\phi = 1.2$$) 注入到 1500 K 的热腐蚀横流中。模拟的反应流稳态已根据先前出版物中的实验和重点目前的工作是射流的瞬态自燃。结果表明，在迎风射流混合层中以反应斑块形式出现的非常稀薄的混合物部分会发生自燃。这些斑块生长，横向包裹射流并延伸到再循环区域。进行化学爆炸模式分析以识别化学活性区域，这些区域是发生自燃的补丁的前体。结果表明，自燃发生在非常稀薄的燃料浓度区域，该区域比射流和横流的最具反应性的混合物部分更稀薄和更热。这是由于在这些非常贫瘠的区域中标量耗散显着降低的事实。最终，峰值热释放移向更丰富的区域，自燃级联控制稳态火焰锚定。