Dynamically evaluating mixture effects on multi-channel reactions in flames: A case study for the CH3 + OH reaction
Dynamically evaluating mixture effects on multi-channel reactions in flames: A case study for the CH3 + OH reaction
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DOI：
10.1016/j.proci.2020.06.187
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发表时间：
2020-08
期刊：
影响因子：
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通讯作者：
Lei Lei-Lei;M. P. Burke
中科院分区：
文献类型：
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作者：
Lei Lei-Lei;M. P. Burke
络合物形成反应的速率常数取决于周围浴气体的压力和碰撞能量转移特性，在燃烧动力学中发挥着重要作用。在最现实的燃烧环境中，多种不同的碰撞能量传递特性大量存在，因此有助于此类系统中涉及的碰撞能量传递。最近的研究表明，多组分压力依赖性的某些表示（即“混合规则”）和/或未能实施混合规则可能会导致误差达到一个数量级，而最近提出的混合规则产生的误差小于 10%。本研究比较了代表火焰中多通道 CH3+ OH 反应的多组分压力依赖性的各种混合物规则的性能，使用一种新颖的动态程序来评估混合物效应作为反应进程（即局部温度、压力和混合物组成）的函数。该过程使得能够在当前的燃烧代码中模拟混合物效应，尽管代码尚未具有旨在捕获这些混合物依赖性效应的函数形式。该程序的结果结合了主方程模拟和动力学传递模拟，表明最近提出的基于减压的混合规则比以前基于绝对压力的混合规则提供了对 CH3+ OH 的混合效应更准确的表示。此外，目前的结果表明，许多模型中没有考虑到 CH3+ OH 反应的混合效应，但它对层流火焰速度的预测具有显着影响，其程度与模型开发研究中激励参数调整的差异相当。
Complex-forming reactions, whose rate constants depend on pressure and collisional energy transfer characteristics of the surrounding bath gas, play a major role in the kinetics of combustion. In most realistic combustion environments, multiple species of distinct collisional energy transfer characteristics are present in significant quantities and thus contribute to collisional energy transfer involved in such systems. Recent studies have indicated that certain representations of multi-component pressure dependence (i.e. “mixture rules”) and/or a failure to implement a mixture rule can result in errors reaching an order of magnitude, whereas recently proposed mixture rules yield errors less than 10%. The present study compares the performance of various mixtures rules for representing multi-component pressure dependence of the multi-channel CH3+ OH reaction in flames, using a novel dynamic procedure for evaluating mixture effects as a function of reaction progress (viz. local temperature, pressure, and mixture composition). This procedure enables mixture effects to be simulated in current combustion codes despite codes not yet having functional forms intended to capture these mixture dependence effects. Results from this procedure, combining master equation simulations and kinetic-transport simulations, indicate that recently proposed mixture rules based on the reduced pressure provide a considerably more accurate representation of mixture effects for CH3+ OH than previous mixture rules based on the absolute pressure. Furthermore, the present results demonstrate that mixture effects for the CH3+ OH reaction, which are not accounted for in many models, have a significant effect on predictions of the laminar flame speed – of comparable magnitude to differences motivating parameter adjustments in model development studies.