A flamelet model is applied to the simulation of axisymmetric counterflow laminar flames including gravitational acceleration and the geometrical details of main nozzles and annular shrouds. The flamelet chemistry model consists of two mixture fractions and is found to be very accurate when compared to results obtained with finite rate chemistry and mixture-average transport. Steady and unsteady solvers are implemented within the OpenFOAM framework. We perform simulations of pressurised counterflow flames for which experimental results are available. Further, we discuss key numerical aspects, including the prescription of robust boundary conditions that ensure steady solutions in the presence of buoyancy effects, the convergence rates of the residuals, issues related to mesh refinement, and the parallel performance of the steady and unsteady solvers. Finally, we apply the framework to a parametric study on the dependence of the counterflow flame on the governing dimensionless groups, i.e. Reynolds and Richardson numbers, and select boundary conditions. The simulations are efficient and enable parametric sweeps with little computational effort.

中文翻译：

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Flamelet 化学模型，用于具有真实喷嘴几何形状和重力体力的高效轴对称逆流火焰模拟

火焰模型应用于轴对称逆流层流火焰的模拟，包括重力加速度和主喷嘴和环形护罩的几何细节。火焰化学模型由两个混合分数组成，与有限速率化学和混合物平均输运获得的结果相比，发现它非常准确。稳态和非稳态求解器在 OpenFOAM 框架内实现。我们对加压逆流火焰进行模拟，实验结果可用。此外，我们讨论了关键的数值方面，包括鲁棒边界条件的规定，以确保在存在浮力效应的情况下稳定解、残差的收敛速度、与网格细化相关的问题、以及稳态和非稳态求解器的并行性能。最后，我们将该框架应用于逆流火焰对控制无量纲群（即雷诺数和理查森数）的依赖性的参数研究，并选择边界条件。模拟是有效的，并且只需很少的计算工作即可实现参数化扫描。