二阶矩亚网格燃烧模型对射流火焰的大涡模拟

Large-Eddy Simulation of a Jet Flame Using a SOM-SGS Combustion Model

用二阶矩亚网格燃烧模型对美国Sandia国家实验室测量甲烷／空气射流火焰进行了大涡模拟(LES),与实验数据和用二阶矩输运方程湍流燃烧模型的雷诺平均(RANS)模拟结果进行了对比．LES得到时间平均的温度, 甲烷浓度以及温度脉动均方根值和实验值符合很好．LES时均值和RANS模拟结果接近,LES脉动均方根值优于 RANS模拟结果．LES瞬态结果显示了有燃烧时的拟序结构比无燃烧时的强,同时拟序结构强化了燃烧,湍流射流火焰呈皱折火焰面的状态．

A second-order moment algebraic （SOM） subgrid scale （SGS） combustion model was adopted for the 3D large eddy simulation of a piloted methane/air jet flame, i.e. Flame C, measured in the Sandia National Laboratory. The predicted time-averaged temperature, methane concentration and root mean square （RMS） value of temperature fluctuation are in good agreement with the experimental data, showing the feasibility of the proposed SGS combustion model. For averaged temperature and species concentration, the RANS-SOM modeling is fairly good. The LES statistical results, in particular for turbulence properties, are better than the RANS modeling results using the same combustion model. The proposed SOM-SGS combustion model is suitable for LES of a jet flame. The instantaneous results show that the coherent structures are abundant in the jet flame and they are enhanced by the reaction. At the same time, the coherent structures intensify the jet combustion, forming a wrinkled flame.