钝体甲烷火焰高掺氢比吹熄机理的大涡模拟

Blow-off Mechanism of High Hydrogen Ratio Bluff Body Methane Flame by Large Eddy Simulation

基于开源软件OpenFOAM使用增厚火焰模型结合甲烷骨架机理,采用大涡模拟研究了实验室尺度高掺氢比甲烷钝体火焰吹熄的过程.通过对比相同流量不同掺氢比的甲烷氢气混合气火焰的吹熄过程,研究高氢含量对吹熄过程的影响.采用OH-PLIF和PIV测量了钝体火焰组分场和流场.模拟与实验结果吻合良好,模拟能够很好地捕捉火焰结构和流场信息.高氢含量工况的放热率显著提高,火焰高度明显降低,回流区长度明显缩短.在钝体火焰吹熄过程中,放热率的降低和拉伸作用对火焰吹熄有不同程度的影响,高氢气含量可以显著提升火焰的抗拉伸能力,但是高氢含量钝体火焰热释放速率的快速降低会导致火焰吹熄过程更为迅速.

High proportion of hydrogen mixed combustion of gas turbine can achieve long-term deep emission reduction and integrate more renewable energy for comprehensive utilization.Based on the open source software OpenFOAM,the large eddy simulation(LES)was used to study the blow-off process of a laboratory scale methane bluff body flame with high hydrogen ratio by using the thickened flame(TF)model and skeleton mechanism.The effect of high hydrogen ratio on the blow-off process was studied by comparing the flames of mixed gases of 30%H2 and 90%H2 with the same flow rate.OH-PLIF and PIV were used to measure the flow field and flame structure of bluff body flame.The simulation and experimental results show that the simulation results are in good agreement with the experimental ones,and that the simulation can well capture the flame structure and flow field information.Under high hydrogen ratio,the heat release rate is significantly increased,the flame height is significantly reduced,and the length of recirculation zone is significantly shortened.In the blow-off process,the decrease of heat release rate and stretching effect have influence on blow-off to different degrees.High hydrogen ratio can significantly improve the anti-stretching ability of flame,but the rapid decrease of heat release rate of high hydrogen ratio bluff body flame will lead to a more rapid blow-off process.