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本文采用LES结合FPV湍流燃烧模型数值模拟了钝体驻定火焰的冷态场和燃烧场,与实验数据进行比较,研究了火焰结构和流场特性,并分析了燃烧对流场的影响。结果表明,速度、温度和主要组分浓度的一阶和二阶统计值,均与实验值符合得较好。燃烧发生在当量混合物分数等值线处,先是沿回流区外边缘分布,然后逐渐向中心靠拢,最后在下游处类似于射流火焰。回流区前部当量混合面处的低标量耗散率和高温分布在钝体驻定火焰中起到了关键的作用。燃烧使气体发生膨胀,回流区变长,轴向平均速度和湍动能沿流向衰减速度降低,湍动能在内剪切层处的峰值降低。
In this paper, LES and FPV turbulent combustion model are used to numerically simulate the cold field and combustion field of bluff body stationary flame. Compared with the experimental data, the flame structure and flow field characteristics are studied, and the influence of combustion on the flow field is analyzed. The results show that the first-order and second-order statistics of velocity, temperature and main component concentrations are in good agreement with the experimental data. Burning occurs at the contour of the equivalent mixture fraction, first along the outer edge of the recirculation zone, then gradually toward the center, and finally downstream in a jet flame. The low scalar dissipation rate and the high temperature distribution at the front equivalent mixing surface of the reflow zone play a key role in the bluff body stationary flame. Combustion causes the gas to expand, and the recirculation zone becomes longer. The average axial velocity and turbulent kinetic energy decrease along the flow direction and the turbulent kinetic energy decreases at the inner shear layer.