Regime and morphology of polyhedral bunsen flames
Regime and morphology of polyhedral bunsen flames
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DOI：
10.1016/j.combustflame.2022.112585
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发表时间：
2023-02
影响因子：
4.4
通讯作者：
Yue Weng;Aditya Potnis;Abhishek Saha
中科院分区：
文献类型：
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作者：
Yue Weng;Aditya Potnis;Abhishek Saha
固有的火焰前缘胞状不稳定性使原本光滑的层流火焰前缘起皱，从而导致过量的表面积和燃烧速率。由于这种不稳定性增加了火焰传播速度和燃烧速率，而没有任何外部影响，如湍流，它们是基本的和实际的兴趣。虽然对自由传播的膨胀火焰或平面火焰进行了广泛的研究，但在燃烧器稳定的预混火焰中也会发生细胞不稳定性。在这项研究中，我们提出了一个实验研究的火焰前锋多面体不稳定性发生在预混本生火焰实际相关的贫氢混合物。通过系统的实验，我们描绘了火焰温度，刘易斯数，和流量的影响，这种火焰的稳定性和形态。结果作为政权地图，以清楚地识别的条件下，火焰表现出的不稳定性，并进一步说明如何过渡边界转移，由于实验条件的变化。此外，火焰的形态也进行了研究，通过确定多面体结构的变化作为操作条件的函数。最后，我们解释了所观察到的多面体火焰的动力学的色散关系和停留时间的分析的帮助。
Intrinsic flamefront cellular instabilities wrinkle, otherwise smooth, laminar flamefronts leading to excess surface area and, thus, burning rate. Since such instabilities increase flame propagation speed and burning rate without any external influence, such as turbulence, they are of both fundamental and practical interest. While extensively studied for freely propagating expanding or planar flames, cellular instabilities can also occur in burner-stabilized premixed flames. In this study, we present an experimental investigation of flamefront polyhedral instability occurring in premixed Bunsen flames for practically relevant lean hydrogen mixtures. Through systematic experiments, we delineate the effect of flame temperature, Lewis number, and flow rate on the stability and morphology of such flames. The results are presented as regime maps to clearly identify the conditions for which the flame manifests the instabilities and further illustrate how the transitional boundaries shift due to changes in experimental conditions. Moreover, the morphology of the flames was also investigated by identifying changes in the polyhedral structure as a function of operating conditions. Finally, we explain the observed dynamics of the polyhedral flames with the aid of analyzes of dispersion relation and residence time.