Propagation of premixed flames in the presence of Darrieus–Landau and thermal diffusive instabilities
Propagation of premixed flames in the presence of Darrieus–Landau and thermal diffusive instabilities
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DOI：
10.1016/j.combustflame.2020.02.030
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发表时间：
2020-06
影响因子：
4.4
通讯作者：
F. Creta;P. E. Lapenna;R. Lamioni;N. Fogla;M. Matalon
中科院分区：
文献类型：
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作者：
F. Creta;P. E. Lapenna;R. Lamioni;N. Fogla;M. Matalon
我们研究的预混火焰的传播，在没有外部湍流的情况下，根据流体动力学（Darrieus-Landau）和热扩散不稳定性的影响。在一个合适的参数空间的Sivashinsky方程的初步利用参数化调查的火焰传播速度的潜在作用下的两种不稳定性。一个适当的变量变换表明，传播速度可以崩溃的一个普遍的标度律作为一个参数的函数的不稳定的波长的数量在domainnc。为了评估这幅图是否可以持续在现实的火焰，DNS数据库的大规模，二维火焰，包括一系列的nc值和受纯流体动力学不稳定性（DL）或两种不稳定性（TD）。借助类似的DNS数据库从文献中，我们观察到，当充分重新缩放，传播速度遵循两个不同的标度律，这取决于热扩散不稳定性的存在或缺乏。我们验证了二次截止值foridentifying的存在（a）在纯流体动力学不稳定火焰和（B）在热扩散不稳定火焰的区域独立性的实现二次燃烧的叛乱。本文还提出了一种基于火焰面密度的亚网格燃烧模型。
We study the propagation of premixed flames, in the absence of external turbulence, under the effect of both hydrodynamic (Darrieus–Landau) and thermodiffusive instabilities. The Sivashinsky equation in a suitable parameter space is initially utilized to parametrically investigate the flame propagation speed under the potential action of both kinds of instability. An adequate variable transformation shows that the propagation speed can collapse on a universal scaling law as a function of a parameter related to the number of unstable wavelengths within the domainnc. To assess whether this picture can persist in realistic flames, a DNS database of large scale, two-dimensional flames is presented, embracing a range ofncvalues and subject to either purely hydrodynamic instability (DL) or both kinds of instability (TD). With the aid of similar DNS databases from the literature we observe that when adequately rescaled, propagation speeds follow two distinct scaling laws, depending on the presence of thermodiffusive instability or lack thereof. We verify the presence of secondary cutoff values forncidentifying (a) the insurgence of secondary wrinkling in purely hydrodynamically unstable flames and (b) the attainment of domain independence in thermodiffusively unstable flames. A possible flame surface density based model for the subgrid wrinkling is also proposed.