Instability transition of a jet diffusion flame in quiescent environment
Instability transition of a jet diffusion flame in quiescent environment
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DOI：
10.1016/j.proci.2020.07.086
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发表时间：
2020-09
期刊：
影响因子：
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通讯作者：
Haodong Zhang;X. Xia;Yi Gao
中科院分区：
文献类型：
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作者：
Haodong Zhang;X. Xia;Yi Gao
本文研究了静止环境中射流扩散火焰的不稳定转变。以往的研究报告存在两种不稳定模式，静脉曲张和蜿蜒，根据他们的动力学特征。为了提供一个统一的分类，这不仅允许量化的两种不稳定模式，但它们之间的过渡，我们提出了一个新的标准的基础上的火焰对称性。应用这个量化，我们表明，扩散火焰的不稳定性从对称过渡到非对称模式，增加燃料率或减小喷嘴直径。为了探索这种转变的本质，我们进行了量纲分析，并确定了两个参数，弗劳德数（Fr）和雷诺数（Re）。后者对射流扩散火焰模式转变的影响以前没有发现。在Re-Fr参数空间上绘制的状态图证实了射流扩散火焰的不稳定性转变由这两个参数决定，Fr主导浮力驱动火焰，Re主导动量驱动火焰。
This paper studies the instability transition of a jet diffusion flame in quiescent environment. Previous study reported the existence of two instability modes, varicose and sinuous, based on their dynamical features. To provide a uniform classification, which allows for quantifications of not only the two instability modes but also the transition between them, we propose a new criterion based on the flame symmetry. Applying this quantification, we show that the instability of diffusion flames transitions from symmetric to asymmetric modes with increasing fuel rate or decreasing nozzle diameter. To explore the essence governing this transition, we performed dimensional analysis and identified two parameters, the Froude number (Fr) and the Reynolds Number (Re). The effect of the latter on the mode transition of jet diffusion flames has not been discovered previously. The regime diagram plotted on theRe-Frparameter space verifies that the instability transition of jet diffusion flames is dictated by these two parameters, withFrdominating the buoyancy-driven flames andRedominating the momentum-driven flames.