Flame stability under flow-induced anisotropic diffusion and heat loss
Flame stability under flow-induced anisotropic diffusion and heat loss
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流动引起的各向异性扩散和热损失下的火焰稳定性
DOI：
10.1016/j.combustflame.2022.112588
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发表时间：
2023
影响因子：
4.4
通讯作者：
Daou J
中科院分区：
文献类型：
--
作者：
Daou J
研究了考虑流动增强扩散或泰勒色散和热损失的预混火焰二维模型。这是第一个解决泰勒色散对非绝热火焰热扩散不稳定性影响的分析研究。这也是第一个将火焰不稳定性与泰勒色散耦合的数值研究。在无限泽尔多维奇数β极限下进行线性稳定性分析。这导致了色散关系，概括了文献中的经典关系，并涉及三个参数：l（简化的路易斯数）、p（与佩克莱特数成正比的泰勒色散系数）和 κ（热损失系数）。确定了稳定性图并讨论了它们对细胞和振荡不稳定性的影响。导出了包含参数 l、p 和 κ 的 Kuramoto-Sivashinsky 型方程，并表征细胞不稳定开始时弱非线性区域中的火焰动力学。理论结果证明泰勒色散和热损失显着影响火焰稳定性的能力。特别是，我们发现 κ 的增加会促进振荡不稳定性，而 p 的增加会阻碍振荡不稳定性。另一方面，p 和 κ 都具有与细胞不稳定性相关的不稳定作用。此外，该理论还提供了一个公式来预测首先从细胞不稳定性中出现的细胞的典型大小，该不稳定性被发现是 p 的递减函数。进行了数值模拟，说明并显着扩展了分析结果。特别注意β的影响。特别是，我们协调了数值预测和理论预测之间明显的定量和有时定性的差异，发现对于较大的 p 值，这种差异更为明显。幸运的是，渐近理论被发现是稳健的，因为如果 β 取得足够大，它的预测就可以在数值上恢复，尽管这样的预测对于 β 的实际值可能是有问题的。一般来说，β 对火焰稳定性的影响与 p 的影响相反：p 的增加或 β 的减少具有与细胞不稳定性相关的不稳定效应，以及与振荡不稳定性相关的稳定效应； κ 的增加会加剧这两种不稳定性。
A two-dimensional model for premixed flames accounting for flow-enhanced diffusion or Taylor dispersion and heat loss is investigated. This is the first analytical study addressing the effect of Taylor dispersion on the thermo-diffusive instabilities of non-adiabatic flames. It is also the first numerical study coupling flame instability with Taylor dispersion. A linear stability analysis is carried out in the limit of infinite Zeldovich number β. This leads to a dispersion relation, generalising classical relations in the literature, and involving three parameters, l (the reduced Lewis number), p (the Taylor-dispersion coefficient which is proportional to the Peclet number), and κ (the heat loss coefficient). Stability diagrams are determined and their implications on the cellular and oscillatory instabilities are discussed. A Kuramoto–Sivashinsky type equation incorporating the parameters l, p and κ and characterising the flame dynamics in the weakly non-linear regime near the onset of the cellular instability is derived. The theoretical results demonstrate the ability of Taylor dispersion and heat loss to significantly affect the flame stability. In particular, the oscillatory instability is found to be promoted by an increase in κ and hampered by an increase in p. On the other hand, both p and κ have a destabilising effect in connection with the cellular instability. Also, the theory provides a formula predicting the typical size of cells first emerging from the cellular instability which is found to be a decreasing function of p. Numerical simulations are carried out illustrating and significantly extending the analytical findings. Particular attention is devoted to the influence of β. In particular, we reconcile apparent quantitative and sometimes qualitative discrepancies between the numerical and theoretical predictions, which are found to be more pronounced for larger values of p. Luckily, the asymptotic theory is found to be robust in the sense that its predictions are recovered numerically if β is taken large enough, although such predictions may be questionable for realistic values of β. In general, the effect of β on flame stability is found to be opposite to that of p: an increase in p or a decrease in β have a destabilising effect in connection with the cellular instability, and a stabilizing effect in connection with the oscillatory instability; both instabilities are promoted by an increase in κ.
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影响因子：
3.7
作者：
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DOI：
--
发表时间：
1994
期刊：
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2.4
作者：
E. Sarraf;C. Almarcha;Joël Quinard;Basile Radisson;B. Denet
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影响因子：
1.3
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DOI：
--
发表时间：
2002
期刊：
影响因子：
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作者：
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