Soot sensitivity to strain rate is mainly responsible for soot formation intermittence in practical combustion devices. This work provides a fundamental study on soot formation in Soot Formation Oxidation (SFO) counterflow flames at varying strain rates. While the problem has been extensively studied in Soot Formation (SF) configurations, where the dominant process is nucleation, investigations remain scarce in the corresponding SFO cases. In the latter, the high temperatures and strong oxidative environments make the surface reactions prevail over nucleation. The work provides a new dataset for ethylene SFO flames in a wide range of strain rates and sheds light on the main processes concurring in determining soot strain rate sensitivity in such conditions. In particular, the peak of soot volume fraction (SVF) is primarily controlled by surface growth and oxidation. The latter becomes progressively more dominant on the side of the SVF distribution toward the oxidizer nozzle, where the presence of oxidizing agents is significant. The soot mechanism adopted predicts a SVF distribution and sensitivity to strain rate in agreement with experimental data. The latter is found similar to corresponding SF cases, although soot loads in the two configurations differ by almost an order magnitude, and the SVF sensitivity is known to be more accentuated for lower soot loads. A deeper investigation revealed that the nucleation process through dimerizations primarily controls the SVF sensitivity, providing the onset of soot necessary for further growth. Then, the latter tends to reduce SVF sensitivity depending on its impact. PAH sensitivities mostly agree with theoretical observation even though further validations on the kinetic mechanism are needed to improve its predictions in lean conditions. The simplistic yet effective model based on the hybrid method of moments and the employment of a reduced kinetic mechanism makes the approach amenable for turbulent computational fluid dynamic (CFD) simulations.

烟灰对应变率的敏感性是实际燃烧装置中烟灰形成间歇性的主要原因。这项工作提供了在不同应变率下烟灰形成氧化 (SFO) 逆流火焰中烟灰形成的基础研究。虽然该问题已在烟灰形成 (SF) 配置中得到广泛研究，其中主要过程是成核，但在相应的 SFO 案例中的调查仍然很少。在后者中，高温和强氧化环境使表面反应优于成核。这项工作为各种应变率下的乙烯 SFO 火焰提供了一个新的数据集，并阐明了在这种条件下确定烟尘应变率敏感性的主要过程。尤其是，烟灰体积分数 (SVF) 的峰值主要受表面生长和氧化控制。后者在 SVF 分布朝向氧化剂喷嘴的一侧逐渐变得更加主导，其中氧化剂的存在很重要。采用的烟灰机制预测 SVF 分布和对应变率的敏感性与实验数据一致。后者被发现类似于相应的 SF 情况，尽管两种配置中的烟尘负载几乎相差一个数量级，并且已知 SVF 灵敏度对于较低的烟尘负载更为突出。更深入的研究表明，通过二聚化的成核过程主要控制 SVF 敏感性，提供进一步生长所需的烟灰开始。然后，后者往往会根据其影响降低 SVF 敏感性。尽管需要进一步验证动力学机制以改进其在贫油条件下的预测，但 PAH 敏感性大多与理论观察一致。基于力矩混合方法和简化动力学机制的采用的简单而有效的模型使该方法适用于湍流计算流体动力学 (CFD) 模拟。