Abstract A novel micro non-premixed combustor with a flame holder and preheating channels is developed to improve the non-premixed flame stabilization for the first time. The numerical results indeed show that the methane-air non-premixed flames can maintain stable with no flashback or pulsating flame even at the stoichiometric ratio compared to the premixed flame, which indicates that the flame stabilization in the present combustor is indeed excellent. The maximum flame temperature at each operating condition is higher than the corresponding adiabatic flame temperature. The excess enthalpy ratio (Reer) is larger at a smaller nominal equivalence ratio (ϕ) and a bigger Reynolds number (Re), and the maximum Reer reaches 36.7%. With the decrease of ϕ, the area of excess enthalpy zone increases at smaller Re ( 0.6), the flame top presents the “Λ” shape, which is significantly different from the flame topology structure of methane/air premixed flame. The standoff distance (Sroot) between the flame root and the flame holder at the larger Re decreases firstly and then increases with the decrease of ϕ, and the anomalous and non-monotonic Sroot are both found. These interesting flame propagation features are reported for the first time for the micro non-premixed flame. Researchers can gain insight into micro non-premixed flame propagation characteristics under the competitive effect between the combustion reaction and mixed performance through the present work.

中文翻译：

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具有火焰稳定器和预热通道的新型微型非预混燃烧器中甲烷-空气的过量燃烧

摘要 为了提高非预混火焰的稳定性，开发了一种新型的带有火焰稳定器和预热通道的微型非预混燃烧器。数值结果确实表明，与预混火焰相比，甲烷-空气非预混火焰即使在化学计量比下也能保持稳定，没有回火或脉动火焰，这表明本燃烧器中的火焰稳定性确实非常好。每种工况下的最高火焰温度都高于相应的绝热火焰温度。标称当量比(ϕ)越小、雷诺数(Re)越大，过剩焓比(Reer)越大，最大Reer达到36.7%。随着 ϕ 的减小，在 Re ( 0.6) 较小时，过剩焓区的面积增加，火焰顶部呈现“Λ”形，与甲烷/空气预混火焰的火焰拓扑结构有显着差异。在较大 Re 处，火焰根部与火焰稳定器之间的间隔距离（Sroot）随着 ϕ 的减小先减小后增大，同时发现了异常和非单调的 Sroot。这些有趣的火焰传播特征首次报道了微非预混火焰。通过目前的工作，研究人员可以深入了解在燃烧反应和混合性能之间的竞争作用下的微观非预混火焰传播特性。在较大 Re 处，火焰根部与火焰稳定器之间的间隔距离（Sroot）随着 ϕ 的减小先减小后增大，同时发现了异常和非单调的 Sroot。这些有趣的火焰传播特征首次报道了微非预混火焰。通过目前的工作，研究人员可以深入了解在燃烧反应和混合性能之间的竞争作用下的微观非预混火焰传播特性。在较大 Re 处，火焰根部与火焰稳定器之间的间隔距离（Sroot）随着 ϕ 的减小先减小后增大，同时发现了异常和非单调的 Sroot。这些有趣的火焰传播特征首次报道了微非预混火焰。通过目前的工作，研究人员可以深入了解在燃烧反应和混合性能之间的竞争作用下的微观非预混火焰传播特性。