基于耦合含氮详细反应机理的有限速率模拟，可考虑无焰燃烧的强烈湍流化学反应交互，并提高燃烧关键参数及NO生成的数值预测精度。建立合理的计算加速方法可在不显著牺牲模拟精度的条件下实现大幅度计算加速。基于CH4/H2热伴流无焰燃烧高保真数值模拟，发展了原位自适应制表与动态自适应机理耦合计算方法并进一步分析了无焰燃烧氮转化机制。评估发现耦合计算方法相较于单一算法，可保证模拟所需的较高精度并成倍提高计算速度。合理的误差阈值可进一步优化计算，且动态自适应机理简化阈值为10-2时综合最佳。耦合计算方法对高复杂度机理有更大的简化空间，如某含氮详细反应机理（151种组分、1 397步反应）经简化后可获得约10.8倍的计算加速。基于经实验验证的模拟结果和氮转化路径分析，CH4/H2热伴流无焰燃烧NO生成主要取决于NNH路径和N2O中间体路径，热力型NO与快速型NO可忽略不计。相较于原位自适应制表法，基于耦合计算方法的氮转化路径分析可保留主要NO反应路径并适当精简。

Based on the finite-rate numerical simulation coupled with detailed reaction mechanisms of nitrogen, the strong turbulence-chemistry interaction in flameless combustion can be considered, and the prediction accuracy of key combustion parameters and NO formation can be improved. A reasonable fast calculation method was builded that can greatly accelerate the calculation without significantly sacrificing the simulation accuracy. A coupled calculation method of In-Situ Adaptive Tabulation and Dynamic Adaptive Chemistry was developed based on the high-fidelity numerical simulations of CH4/H2 flameless combustion with a hot co-flow, then the nitrogen conversion mechanisms of flameless combustion was further analyzed. It is found that the coupled calculation method can ensure the higher accuracy required for the simulations and double the calculation speed compared with a single method. It can be further optimized with a reasonable error threshold and the Dynamic Adaptive Chemistry threshold 10-2 performs best overall. The coupled calculation method has a larger simplification space for high-complexity mechanisms, and a nearly 10.8 times calculation acceleration is obtained with one detailed reaction mechanism of nitrogen containing 151 species and 1 397 reactions. Based on the experimental validation and the nitrogen conversion path analysis, the NO formation of CH4/H2 flameless combustion with a hot co-flow mainly depends on the NNH path and the N2O intermediate path, while thermal-NO and prompt-NO can be ignored.Compared with the In-Situ Adaptive Tabulation, the nitrogen conversion path analysis can be properly simplified and the main NO paths can be retained with the coupled calculation method.

0 引言

1 基于ISAT-DAC算法的数值模拟

   1.1 原位自适应制表法

   1.2 动态自适应机理简化

   1.3 模拟对象与计算细节

2 模拟结果与讨论

   2.1 简化算法的发展评估

   2.2 动态自适应机理最优简化阈值

   2.3 不同复杂度机理的简化效果

   2.4 实验验证与氮转化路径分析

3 结论