简化的联合PDF模型模拟湍流燃烧中NO生成

Prediction of NO formation in turbulent combustion using presumed joint PDF model

为克服现有工程中模拟污染物生成模型存在的缺陷,采用简化的联合概率密度函数(PDF)模型预报了甲烷燃烧过程,得到的温度场及反应物和产物浓度场与实验结果相符。在此基础上,采用Zeldovich机理及简化的联合PDF湍流反应模型预报了甲烷燃烧过程中热力型NO的生成,并与实验及Arrhenius模型的预报结果进行了比较。结果表明,简化的联合PDF模型给出的NO分布与实验结果相符,而Arrhenius模型的预报值则远低于实验值。说明简化的联合PDF模型能够综合考虑湍流和反应动力学两方面的影响,合理预报NO的生成过程。

CH4/air diffusion turbulent combustion was numerically simulated using a presumed joint PDF model. The predicted results of temperature and species concentrations agree well with the experimental data. Based on this reasonable prediction of turbulent combustion, the extended Zeldovich mechanics for the thermal NO formation and the presumed joint PDF model for turbulent reaction are adopted to predict NO formation in CH4/air diffusion turbulent combustion. Comparison between the experimental data and the prediction results using the presumed joint PDF model and Arrhenius model shows that the predicted NO values using the PDF model agree well with the experimental data, while those using Arrhenius model were largely underestimated. Therefore, the presumed joint PDF model can provide quantitative simulation of thermal NO in consideration of effects of both turbulent diffusion and chemical dynamics.