高温下掺氢天然气层流预混火焰传播特性

利用本生灯-纹影系统及CHEMKIN-PRO对高温下掺氢天然气层流预混火焰传播速度进行实验及数值模拟研究，并从热力学及化学动力学效应方面讨论了初始温度对掺氢天然气层流预混火焰传播特性的影响.结果表明:GRI-3.0机理能较准确地预测293~500K条件下的掺氢天然气层流预混火焰传播速度;在相同初始温度下，混合物层流预混火焰传播速度在高掺氢比时增幅更显著;在相同当量比下，混合物层流预混火焰传播速度及绝热火焰温度随初始温度的升高呈近线性增加;高温下，H自由基浓度的增大进一步增强了H+O₂=O+OH对整体燃烧反应的促进作用，使混合物层流预混火焰传播速度显著加快.

Propagation of Laminar Premixed Flames of CH4 /H2 /Air Mixtures at Elevated Temperatures

The laminar flame speeds of CH₄/H₂/air mixtures were experimentally studied at elevated initial temperatures using the Bunsen burner method combined with the Schlieren technique， and the corresponding cases were computed using CHEMKIN-PRO. The effect of initial temperatures on the propagation characteristics of laminar premixed flames was discussed from the perspectives of thermodynamics and chemical kinetics. The results show that the laminar flame speeds of the mixtures at 293-500K can be predicted well by GRI-3.0 mechanism. The greater increments of laminar flame speeds of mixtures are presented at higher H₂ fractions under all tested initial temperatures. The laminar flame speeds and adiabatic flame temperatures of mixtures almost linearly increase with a growth of initial temperatures with the same equivalence ratios. With the rise of initial temperatures， the dominant promotion of H+O₂=O+OH on the mass burning rates of mixtures can be enhanced by the great growth of the mole fractions of H radicals. Therefore， the laminar flame speed of CH₄/H₂/air mixtures significantly increases at elevated temperatures.