Stratified propane air flames stabilized in the near wake region of a premixer/disk arrangement were investigated for a variety of inlet mixture compositions and preheating temperatures. The employed burner is capable of anchoring flames at very lean mixtures, expanding the lean flammability limits and promoting flame stabilization, at global equivalence ratio values of \(\Phi =0.13\) at 743 K. Particle Image Velocimetry and \({\text{OH}}^{*}\) Chemiluminescence Image analysis were performed to investigate flame stabilization characteristics at four inlet preheat levels ranging from 300 to 743 K, for fuel-lean reactant concentrations. Inlet mixture reactivity, 2D aerodynamic stretch rates, Damköhler (\(Da\)) and Karlovitz (\(Ka\)) numbers and flame brush thicknesses were estimated and analyzed to elucidate the effects of turbulence, inlet preheat and mixture composition on the flame topology and anchoring characteristics. Results show that the simultaneous stratification and preheat of the inlet mixture has a notable effect on the turbulent flame stabilization, with \(Ka\) numbers up to 60, for the highly preheated, ultra-lean flames, suggesting that the flames are chemically controlled with turbulence playing a less significant role. Moreover, the 2D aerodynamic stretch rates, evaluated along the mean flame front path, revealed that flame quenching requires both a certain level of mean stretch and a sufficiently large probability of these values to be exerted on the flame. Considering the stretch rate distributions and the respective \(Da\) numbers along the flame sheet it could be conjectured that laminar extinction stretch rates can be used as reference, for turbulent flames, only when the local \(Da\) number exceeds unity.

研究了在预混器/圆盘装置的近尾流区域稳定的分层丙烷空气火焰，用于各种进气混合物成分和预热温度。使用的燃烧器能够在743 K的全局当量比值为\（\ Phi = 0.13 \）的情况下，将火焰固定在非常稀薄的混合物中，扩大稀薄的可燃性极限并促进火焰稳定。粒子图像测速和\（{\ text {OH}} ^ {*} \）化学发光进行图像分析以研究贫油反应物浓度在300到743 K的四个入口预热水平下的火焰稳定特性。入口混合物反应性，二维空气动力学拉伸率，Damköhler（\（Da \））和Karlovitz（\（Ka \）估算并分析了火焰刷的数量和厚度，以阐明湍流，入口预热和混合物组成对火焰拓扑和锚固特性的影响。结果表明，进气混合物的同时分层和预热对湍流火焰稳定有显着影响，具有（Ka）对于高度预热的超稀薄火焰，其数值最多为60，这表明火焰是通过化学控制的，湍流起的作用较小。此外，沿平均火焰前沿路径评估的2D空气动力学拉伸速率表明，火焰淬火既需要一定水平的平均拉伸，又需要足够大的概率将这些值施加到火焰上。考虑到沿火焰片的拉伸速率分布和各自的\（Da \）数，可以推测，仅当局部\（Da \）值超过1时，层流消光拉伸速率才可以用作湍流火焰的参考。