甲烷/空气射流抬举火焰的大涡模拟计算

Large Eddy Simulation of CH_4/Air Lifted Flame

为了研究中高温伴流中的自动着火特性,采用大涡模拟(LES)和均匀搅拌器(PSR)结合假定概率密度函数的建表湍流燃烧模型对甲烷/空气射流在高温伴流中的抬举火焰数值研究,并比较反应进度的不同概率密度分布对结果的影响。结果表明,计算结果与实验值符合得较好。PSR建表方法能够捕捉到高温伴流抬举火焰的点火过程,能够正确预测火焰的抬举高度,但在火焰稳定燃烧区域该建库燃烧模型还存在不足。同时,反应进度的亚格子脉动对准确模拟抬举高度十分重要。

Large eddy simulation(LES) and tabulated table using perfectly stirred reactor(PSR) combined with presumed probability density function(PDF) combustion model were applied to investigate the lifted flame of CH4/air jet in high temperature coflow. The effect of different shapes of PDF for progress variable was investigated. The numerical results indicate that distribution of temperature and mass fractions of major compositions in different relative locations are in good agreement with the experimental data. The method of tabulated table with PSR can capture the auto-ignition process of the flame and the lifted height of the flame,but performs not so good in the stable flame zone. The results also show that the sub-grid variance of the progress variables is essential to predict lifted height correctly.