Head-on quenching is a canonical configuration for flame-wall interaction. In the present study, the transient process of a laminar premixed flame impinging on a wall is investigated for different strain rates, while previous studies with detailed chemistry and transport focused only on unstrained conditions. Increasing strain rate leads to a reduction in the normalized quenching distance, and an increase in the normalized wall heat flux, both are considered as global flame quantities. Looking more into the local microstructure of the quenching process, CO formation and oxidation near the wall are shifted to higher temperatures under higher strain rates. Further, the local flame structure and the thermochemical state are affected by differential diffusion driven by differences in species’ gradients and diffusivities. Quenching leads to increased species’ gradients and consequently differential diffusion is amplified near the wall compared to propagating flames. However, this effect is suppressed for increasing strain rates, which is explained in more detail by a source term analysis of the transport equation for the differential diffusion parameter Z HC . Results for the global quantities and the local flame structure show that the impact of the strain rate weakens for higher wall temperatures. Finally, the analyses of the thermo-chemical quantities in the composition space shows that H 2 can be a good parameter to characterize the strain rate both for propagating and quenching flamelet.

中文翻译：

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层流预混甲烷-空气火焰迎面淬火的应变率效应

正面淬火是火焰-壁相互作用的典型配置。在本研究中，针对不同应变率研究了层流预混火焰撞击壁的瞬态过程，而先前的详细化学和传输研究仅侧重于无应变条件。增加应变率会导致标准化淬火距离的减少和标准化壁面热通量的增加，两者都被视为全局火焰量。更多地观察淬火过程的局部微观结构，壁附近的 CO 形成和氧化在更高的应变速率下转移到更高的温度。此外，局部火焰结构和热化学状态受到由物种梯度和扩散率差异驱动的差异扩散的影响。淬火导致物种梯度增加，因此与传播火焰相比，靠近壁的差异扩散被放大。然而，随着应变率的增加，这种效应被抑制，这可以通过微分扩散参数 Z HC 的传输方程的源项分析进行更详细的解释。全局量和局部火焰结构的结果表明，应变率的影响随着壁温升高而减弱。最后，对成分空间中的热化学量的分析表明，H 2 可以是表征传播和淬火小火焰的应变速率的良好参数。这种效应会随着应变率的增加而被抑制，这可以通过微分扩散参数 Z HC 的传输方程的源项分析进行更详细的解释。全局量和局部火焰结构的结果表明，应变率的影响随着壁温升高而减弱。最后，对成分空间中的热化学量的分析表明，H 2 可以是表征传播和淬火小火焰的应变速率的良好参数。这种效应会随着应变率的增加而被抑制，这可以通过微分扩散参数 Z HC 的传输方程的源项分析进行更详细的解释。全局量和局部火焰结构的结果表明，应变率的影响随着壁温升高而减弱。最后，对成分空间中的热化学量的分析表明，H 2 可以是表征传播和淬火小火焰的应变速率的良好参数。