Abstract: Nitrogen oxides emission from a series of turbulent methane jet non-premixed flames with different Reynolds number was numerically simulated, in order to investigate the influence of turbulence on the formation of nitrogen oxides.A two-scale k-ε turbulence model was adopted to calculate turbulent velocity field, and the probability density function (PDF) method was combined with the Lagrangian flamelet model to predict the turbulent scalar fields.Detailed chemical reaction mechanism GRI-Mech 3.0 was incorporated to describe methane oxidation and nitrogen oxides formation.The comparisons between nitrogen oxides predictions and measurements were made,and the influence of Reynolds number, scalar dissipation and flamelet time on the formation of nitrogen oxides was discussed. The numerical results were in good agreement with the measurements, and the trend that nitrogen oxides emission decreased with the increase of Reynolds number in the experiment was reasonably represented by the present numerical models.

摘要：

对一系列具有不同Reynolds数的湍流甲烷射流扩散火焰中氮氧化物的排放进行了数值模拟，以考察湍流对氮氧化物排放的影响.采用一个双尺度的k-ε湍流模型计算速度场，将概率密度函数（PDF）方法和Lagrangian火焰面模型相结合求解标量场，燃料甲烷的氧化过程和氮氧化物的生成过程采用详细的GRI-Mech 3.0机理描述.将氮氧化物的计算结果和实验数据进行了比较，并探讨了Reynolds数、标量耗散和火焰面时间对氮氧化物排放的影响.发现计算结果和实验数据符合较好，计算模型正确预测了氮氧化物的生成量随着Reynolds数的增加而减少的趋势.