The effects of differential diffusion and stretch sensitivity on propagation and stabilization of lean premixed hydrogen-enriched methane-air and propane-air flames are studied in a turbulent counter-flow apparatus. In these experiments, the unstretched laminar flame speed is kept constant through decreasing the mixture equivalence ratio, in order to minimize the effects of chemistry and highlight the effects of differential diffusion during hydrogen-enrichment. Bulk flow properties are also kept constant between laminar and turbulent flames. High-speed particle image velocimetry (PIV) is applied to quantify the flow velocity field using oil droplet seeding, enabling simultaneous flame position and velocity measurements. Data processing tools are developed through this study to quantify instantaneous local measurements of flame position, flame curvature, and apparent turbulent flame velocity within the imaged plane. Probability density functions (PDF) of instantaneous flame position show that, in hydrogen-enriched methane-air flames (effective Lewis number < 1), differential diffusion increases the turbulent burning rates throughout the whole hydrogen-enrichment range. However, in hydrogen-enriched propane-air flames, these effects are only observed at hydrogen content above 60% (by volume), where effective Lewis number falls below unity. PDFs of flame position also illustrated that the effects of differential diffusion become significant when the effective Lewis number < 0.8. In contrast, PDFs of turbulent flame velocities only showed a slight increase in local instantaneous velocities with increasing hydrogen content. Furthermore, it was illustrated that differential diffusion affects the flame front topology by increasing instantaneous flamelet curvature at below unity Lewis numbers, consistent with flame stability theory.

在湍流逆流装置中研究了微分扩散和拉伸敏感性对稀薄预混合富氢甲烷-空气和丙烷-空气火焰的传播和稳定性的影响。在这些实验中，通过降低混合物当量比，未拉伸的层流火焰速度保持恒定，以便最大程度地减少化学作用并突出氢富集过程中差异扩散的作用。层流和湍流火焰之间的整体流动特性也保持恒定。高速粒子图像测速技术（PIV）用于使用油滴播种来量化流速场，从而能够同时测量火焰位置和速度。通过这项研究开发了数据处理工具，以量化火焰位置的瞬时局部测量值，火焰曲率，以及成像平面内明显的湍流火焰速度。瞬时火焰位置的概率密度函数（PDF）表明，在富氢甲烷-空气火焰（有效路易斯数<1）中，微分扩散会增加整个氢富集范围内的湍流燃烧速率。但是，在富氢丙烷-空气火焰中，只有在氢含量高于60％（按体积计）的情况下才能观察到这些影响，而有效路易斯数却低于1。火焰位置的PDF文件还表明，当有效Lewis数<0.8时，微分扩散的影响变得显着。相反，湍流火焰速度的PDF仅显示局部瞬时速度随氢含量的增加而略有增加。此外，