Abstract Catalytic combustion of natural gas has a growing interest to improve the flame stability and conversion efficiency in microcombustors. In automotive industry, the improvement of the efficiency of catalytic after-treatment systems are one solution to reduce drastically pollutant emissions. These devices present a honeycomb shape which consists in a grid of millimeter-scale narrow channels whose interior walls are coated with precious metals presenting catalytic properties. Fuels or pollutants are converted through the chemical interactions involving gas-phase molecules and catalytic sites. In order to promote transfers, obstacles can be introduced inside the channels. The numerical simulation is mandatory to help understanding and mastering the underlying phenomena. In the present study, a numerical methodology is proposed to couple surface kinetics and gas phase chemistry with boundary conditions accounting for momentum, heat and mass transfers in order to take into account the interactions between the flow and heterogeneous reactions. Numerical simulations are then performed on the experimental configuration by Dogwiler et al. which consists in lean premixed CH4/air mixture igniting in a Pt-coated meso-scale channel with flat walls. The validated numerical methodology is then applied to explore the impact of introducing wall obstacles and segmented coating on the anchoring position of the flame and fuel conversion rate.

中文翻译：

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非平面壁中尺度通道催化燃烧的直接数值模拟

摘要 天然气的催化燃烧对于提高微型燃烧器的火焰稳定性和转化效率越来越受到关注。在汽车行业，提高催化后处理系统的效率是大幅减少污染物排放的一种解决方案。这些装置呈蜂窝状，由毫米级窄通道网格组成，其内壁涂有具有催化性能的贵金属。燃料或污染物通过涉及气相分子和催化位点的化学相互作用进行转化。为了促进转移，可以在渠道内部引入障碍。数值模拟对于帮助理解和掌握基本现象是必不可少的。在目前的研究中，提出了一种数值方法，将表面动力学和气相化学与考虑动量、热量和质量传递的边界条件结合起来，以考虑流动和非均相反应之间的相互作用。然后，Dogwiler 等人对实验配置进行了数值模拟。它包括在具有平坦壁的 Pt 涂层中尺度通道中点燃的贫预混 CH4/空气混合物。然后应用经过验证的数值方法来探索引入壁障碍物和分段涂层对火焰锚定位置和燃料转化率的影响。然后，Dogwiler 等人对实验配置进行了数值模拟。它包括在具有平坦壁的 Pt 涂层中尺度通道中点燃的贫预混 CH4/空气混合物。然后应用经过验证的数值方法来探索引入壁障碍物和分段涂层对火焰锚定位置和燃料转化率的影响。然后，Dogwiler 等人对实验配置进行了数值模拟。它包括在具有平坦壁的 Pt 涂层中尺度通道中点燃的贫预混 CH4/空气混合物。然后应用经过验证的数值方法来探索引入壁障碍物和分段涂层对火焰锚定位置和燃料转化率的影响。