当量比对预混燃烧影响的大涡模拟研究

本文对在突扩燃烧室内甲烷和空气的预混燃烧进行了大涡模拟(LES)研究，考虑预混燃料的当量比对燃烧室提供的动力及产生的污染物的影响．利用LES计算了不同当量比条件下燃烧室内湍流预混燃烧反应流场的温度、浓度、涡量和压力分布,最后对当量比0.5时B点和C点的温度和速度进行EMD分解，得到了温度场和速度场的各阶模态的平均周期．结果表明：随着当量比从0.5增加至0.7，燃烧反应趋于剧烈，燃烧室的最高温度提高了350K，平均压力从32.876 Pa增大到34.833Pa，燃烧产生的瞬态径向最高浓度从0.5%增加到0.95%．

Large Eddy Simulation of the Effects of Equivalence Ratio on Premixed Combustion

In this paper, LES research is carried out on pre-mixing combustion of methane and air in a sudden expansion combustion chamber. The influence of the equivalence ratio of premixed fuel on power supplied for the combustion chamber and the generated pollutants is mainly studied. By means of LES approach, distributions of temperature, concentration, vorticity and pressure of the reaction flow field of turbulent premixed combustion in the combustion chamber under different equivalence ratios are obtained. Finally, the EMD decomposition of the temperature field and velocity field at Point B and C of 0.5 equivalence ratio is carried out, and the average period of each mode of temperature and velocity field is obtained. Analysis results show that as the equivalence ratio increases from 0.5 to 0.7, the combustion reaction becomes more intense. The maximum temperature of the combustion chamber is increased by 350K, the average pressure increases from 32.876pa to 34.833 Pa, and the maximum transient radial concentration from combustion increases from 0.5% to 0.95%.