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为了研究高Karlovitz(Ka)数下湍流预混火焰的驻定机制和火焰结构,采用化学热力学建表方法结合假定概率密度函数(PDF)模型,对值班预混射流火焰(PPJB)进行大涡模拟(LES)研究。选取自点火模型作为建表模型,使用假定PDF模型考虑湍流和化学反应之间的相互作用,其中假定双混合物分数的概率密度分布为Dirichlet分布,反应进度变量的概率密度分布为β分布。模拟结果表明,能较好预测PPJB火焰的温度和主要组分的分布。使用中间组分(CO和OH)的质量分数来定性描述PPJB火焰结构,结果表明高Ka数下火焰结构受到湍流涡旋的显著影响。
In order to study the stationary mechanism and flame structure of turbulent premixed flames under high Karlovitz (Ka) number, large-eddy simulation (LST) was performed on the premixed jet flame (PPJB) on the basis of chemical thermodynamics method and hypothetical probability density function (PDF) (LES) study. The ignition model was chosen as the model of the building table, and the assumed PDF model was used to consider the interaction between turbulence and chemical reaction. The probability density distribution of the mixture fraction was assumed to be the Dirichlet distribution and the probability density distribution of the reaction progress variable was the β distribution. The simulation results show that the PPJB flame temperature and the distribution of the main components can be well predicted. The mass fraction of intermediate components (CO and OH) was used to qualitatively characterize the PPJB flame structure. The results show that the flame structure at high Ka numbers is significantly affected by turbulent eddies.