A highly resolved large eddy simulation (LES) of the semi-industrial IFRF coal furnace [1,2] employing the steady flamelet model is presented. The flamelet table is based on mixture fractions of volatile and char off-gases as well as on enthalpy and scalar dissipation rate. Turbulence–chemistry interaction is treated with an assumed pdf approach, with the variance obtained from a transport equation. Radiation is computed by the discrete ordinates method and the grey weighted sum of grey gases model. The simulation is conducted with the massively parallel “PsiPhi” code on up to 1.7 billion cells and with 40 million particles. Results are processed and compared against the comprehensive set of experiments to (i) validate the new flamelet model and the simulation method and to (ii) gain further insight into the combustion process that is not available from the experiment. The simulation results show that the flamelet LES approach can successfully describe the flow field and combustion inside the furnace; major species and velocities are found in good agreement with the experiment.

The results are further analyzed with a focus on the processes of particle heating, devolatilization, char combustion and flame stabilization in a highly turbulent environment. Additionally, the relative importance of scalar dissipation rate is highlighted, showing a large separation of mixing scales between volatile and char off-gas combustion due to the long residence time and generally much lower scalar dissipation rates than typical for lab-scale experiments.

提出了采用稳定小火焰模型的半工业IFRF煤炉[1,2]的高分辨大涡模拟（LES）。火焰表基于挥发物和焦炭废气的混合比例以及焓和标量耗散率。用假定的pdf方法处理湍流-化学相互作用，并从输运方程中获得方差。辐射是通过离散纵坐标法和灰色气体的灰色加权总和模型来计算的。使用大规模并行的“ PsiPhi”代码对多达17亿个单元和4000万个粒子进行仿真。处理结果并将其与综合实验集进行比较，以（i）验证新的火焰模型和模拟方法，并（ii）进一步洞察该实验无法获得的燃烧过程。仿真结果表明，小火焰LES方法可以成功地描述炉内的流场和燃烧。发现主要物种和速度与实验吻合得很好。

对结果进行了进一步分析，重点是在高度湍流的环境中进行颗粒加热，脱挥发分，炭燃烧和火焰稳定化的过程。此外，标量耗散率的相对重要性也得到了强调，这表明由于停留时间长，挥发分和焦炭废气燃烧之间的混合标度有很大的分离，并且通常比实验室规模的实验要低得多。