Ammonia has been identified as a promising energy carrier that produces zero carbon dioxide emissions when used as a fuel in gas turbines. Although the combustion properties of pure ammonia are poorly suited for firing of gas turbine combustors, blends of ammonia, hydrogen, and nitrogen can be optimized to exhibit premixed, unstretched laminar flame properties very similar to those of methane. There is limited data available on the turbulent combustion characteristics of such blends and important uncertainties exist related to their blow-out behavior. The present work reports experimental measurements of the blow-out limits in an axisymmetric unconfined bluff-body stabilized burner geometry of NH₃/H₂/N₂-air flame, comprised of 40% NH₃, 45% H₂, and 15% N₂ by volume in the “fuel” blend. Blow-out limits for the NH₃/H₂/N₂-air flames are compared to those of methane–air flames. OH PLIF and OH chemiluminescence images of the flames just prior to blow-out are presented. Furthermore, two large-scale Direct Numerical Simulations (DNS) of temporally evolving turbulent premixed jet flames are performed to investigate differences in the turbulence-chemistry interaction and extinction behavior between the NH₃/H₂/N₂-air and methane–air mixtures. The experiments reveal that the blow-out velocity of NH₃/H₂/N₂-air flames is an order of magnitude higher than that of methane–air flames characterized by nearly identical unstretched laminar flame speed, thermal thickness and adiabatic flame temperature. Results from the DNS support the experimental observation and clearly illustrate that a methane–air mixture exhibits a stronger tendency towards extinction compared to the NH₃/H₂/N₂-air blend for identical strain rates. Furthermore, the DNS results reveal that, even in the presence of intense sheared turbulence, fast hydrogen diffusion into the spatially distributed preheat layers of the fragmented and highly turbulent flame front plays a crucial role in the enhancement of the local heat release rate and, ultimately, in preventing the occurrence of extinction.

氨被认为是一种有前途的能源载体，当用作燃气轮机的燃料时，其二氧化碳排放量为零。尽管纯氨气的燃烧性能不太适合燃气轮机燃烧器的燃烧，但是可以优化氨气，氢气和氮气的混合物，以表现出与甲烷非常相似的预混合，未拉伸层流火焰特性。关于这些混合物的湍流燃烧特性的数据有限，并且存在与它们的爆燃行为相关的重要不确定性。本工作报告了由40％NH ₃组成的NH ₃ / H ₂ / N _2-空气火焰的轴对称无侧界钝体稳定燃烧器几何形状中爆燃极限的实验测量。在“燃料”混合物中的体积百分比为45％H ₂和15％N ₂。将NH ₃ / H ₂ / N _2-空气火焰的吹出极限与甲烷-空气火焰的吹出极限进行比较。给出了喷吹之前火焰的OH PLIF和OH化学发光图像。此外，进行了两个随时间变化的湍流预混射流火焰的大规模直接数值模拟（DNS），以研究NH ₃ / H ₂ / N _2-空气与甲烷-空气混合物之间的湍流-化学相互作用和消光行为的差异。。实验表明，NH ₃ / H ₂ / N ₂的吹出速度空气火焰比甲烷空气火焰高一个数量级，其特征在于未拉伸的层流火焰速度，热厚度和绝热火焰温度几乎相同。DNS的结果支持实验观察，并清楚地表明，在相同的应变速率下，与NH ₃ / H ₂ / N _2-空气混合物相比，甲烷-空气混合物显示出更强的灭绝趋势。此外，DNS结果表明，即使存在强烈的剪切湍流，氢也迅速扩散到破碎且高度湍流的火焰前锋的空间分布预热层中，对提高局部放热率起着至关重要的作用，最终，在防止灭绝事件的发生上。