高雷诺数湍流非预混火焰及NO生成的大涡模拟  

Large eddy simulations of high Reynolds number turbulent non-premixed flame and NO formation

作　　者：于洲[1] 黄立航 叶桃红[1] 朱旻明[1] YU Zhou;HUANG Lihang;YE Taohong;ZHU Minming(Department of Thermal Science and Energy Engeering,University of Science and Technology of China,Hefei 230027,China)

机构地区：[1]中国科学技术大学热科学和能源工程系,合肥230027

出　　处：《空气动力学学报》2020年第3期629-640,共12页Acta Aerodynamica Sinica

基　　金：国家自然科学基金(9141117,51576182)。

摘　　要：采用两种亚网格湍流燃烧模型,即化学建表方法结合假定概率密度模型和稀疏拉格朗日过滤密度函数方法,对高雷诺数湍流非预混火焰Flame D进行数值研究,定量比较不同亚网格模型的差异,并对火焰特征、污染生物生成特性进行分析。结果表明,两类亚网格燃烧模型预测的温度及大组分分布相近,稀疏拉格朗日过滤密度函数方法可以更好地模拟CO质量分数分布。不同的假定概率分布均可合理描述湍流与火焰的相互作用,之间的差别主要体现在NO分布,Dirac函数远高估了NO生成,而Top-hat函数则略低估了NO生成,Beta函数表现最优。Flame D的高温区及NO质量分数均主要分布在当量混合线及富燃侧附近。受高温伴流的影响,NO质量分数与温度一直保持高度正相关,峰值主要集中在标量耗散率很小的区域。不同截面上,反应物中的O2和生成物中的H2O均与NO高度相关。Large eddy simulations(LESs)of Sandia turbulent non-premixed flame D have been carried out using two sub-grid scale combustion models.One is tabulated chemistry method coupled with three presumed probability density functions(PPDFs),the other is sparse Lagrangian filtered density function(FDF)method.The goal is to show the differences of the two combustion models and highlight the characteristics of turbulent non-premixed flame and its pollutant.Comparisons of statistical results indicate that the distributions of temperature and major species are similar,while CO can be better captured by the FDF model.Interactions between turbulence and flame(TFIs)can be described reasonably by all the three PPDFs,and the difference between them is mainly reflected in the predicted distributions of NO.NO mass fraction is largely overpredicted with Dirac function,and underestimted with Top-hat function.Beta function presents the best performance in the prediction of NO.Regions of high temperature and mass fraction of NO are mainly located around?=1.0 and rich side.The mass fraction of NO peaks mainly in the region where the scalar dissipation rate of mixture fraction is relatively small.The mass fraction of NO is always highly correlated with local temperature,in the presence of the high temperature piloted flame.It is also highly correlated with the mass fraction of O2 and H2O at different axial locations.

关 键 词：化学建表方法 过滤密度函数方法 假定概率密度函数 湍流非预混火焰 氮氧化物 

分 类 号：V211.3[航空宇航科学与技术—航空宇航推进理论与工程] TK16[动力工程及工程热物理—热能工程]