掺氢比对甲烷-氢微混组合火焰燃烧特性的影响

Efficient utilization of hydrogen-natural gas blend fuel is an essential pathway for existing heavy-duty gas turbine to achieve carbon neutrality goals. To investigate the effects of hydrogen blending on the changes in the flame flow field，further affecting the flame structure and combustion stability，this paper utilized an annular micro-mixing combined nozzle experimental platform to examine how variations in hydrogen blending ratio affect the structural characteristics of methane-hydrogen micro-mixing flames，pressure pulsation characteristics，and NO formation characteristics. Flame structure，pressure pulsation within the combustion zone，and NO emissions of methane-hydrogen flames were investigated using a high-speed visible light camera，dynamic pressure sensors，and flue gas analyzer. Measurements were conducted for hydrogen blending ratios ranging from 50% to 90% and equivalence ratio range of 0.5~0.9. The impact of hydrogen blending on the structure and stability boundaries of methane flames is very significant. When the hydrogen blending ratio exceeds 70%，the micro-mixing combined flames can stably burn within an equivalence ratio range of 0.6~0.9. As the equivalence ratio increases，the heat release zone is elongated，and the flame tends to stabilize in the region near the nozzle outlet. Under the conditions of constant thermal power and equivalence ratio，as the hydrogen blending ratio increases，the air flow rate decreases，leading to a reduction in NO emissions. Under conditions where the equivalence ratio is less than 0.8，the NO emissions are less than 10 μL/L（@15% O₂）.