本文对甲烷和空气在突扩燃烧室内的预混燃烧进行了大涡模拟(LES)研究,主要关注于预混燃料的湍流强度对甲烷-空气预混燃烧效率的影响.LES数值模拟给出了不同入口湍流强度的条件下燃烧室内湍流预混燃烧反应流场的速度场,温度场和浓度场分布.分析的结果表明:随着预混燃料入口湍流强度的增大,燃烧反应更加剧烈,燃烧效率提高,火焰长度也随之变短,同时,一氧化碳的生成区域明显变小,整体生成量减少.研究的结果对有效地提高燃气轮机的燃烧效率和减少污染物的排放提供一定的参考依据. In this paper, a large eddy simulation (LES) study of premixed combustion of methane and air in a combustion chamber with sudden expansion is mainly focused on the effect of turbulence intensity of premixed fuel on the efficiency of methane-air premixed combustion. The results show that with the increase of turbulence intensity at the inlet of the premixed fuel, the combustion reaction is more severe, and the combustion The efficiency will increase and the length of the flame will be shortened.At the same time, the formation area of ​​carbon monoxide will be obviously smaller and the overall production will decrease.The results of the study will provide some reference for effectively improving the combustion efficiency of gas turbine and reducing the emission of pollutants.