Flame Induced Flow Features in the Presence of Darrieus-Landau Instability
Flame Induced Flow Features in the Presence of Darrieus-Landau Instability
复制标题
存在 Darrieus-Landau 不稳定性时的火焰诱导流动特征
DOI：
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发表时间：
2018
影响因子：
2.4
通讯作者：
F. Creta
中科院分区：
文献类型：
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作者：
R. Lamioni;P. E. Lapenna;G. Troiani;F. Creta
流体动力学或Darrieus-Landau（DL）不稳定性的发生对预混火焰形态、湍流火焰速度和诱导流场有很大影响。在这项工作中，我们专注于后者诱导流动的二维直接数值模拟（DNS）的缝隙燃烧器火焰进行参数化的方式。线性稳定性分析的结果被用来选择适当的参数范围进行调查。DL不稳定性的存在下，最初评估使用最近提出的统计标记有关的火焰形态。稳定和不稳定的火焰之间的差异，然后进行统计研究，利用一个单一的，层流，DL-诱导燃烧作为参考状态。在不同的湍流强度，在局部传播，诱导应变率模式和流场以及涡量的产生和转化方面的DL诱导的效果进行了研究。使用位移速度作为衡量当地的传播，没有明显的统计差异，观察稳定和不稳定的火焰，而应变率和涡量模式被证明是在很大程度上受DL诱导的形态。从建模的角度来看，增强湍流标量通量的反梯度型传输观察流体动力学不稳定火焰。
The onset of hydrodynamic or Darrieus-Landau (DL) instability can largely impact on premixed flame morphology, turbulent flame speed and induced flow field. In this work, we focus on the latter induced flow by means of two dimensional direct numerical simulations (DNS) of slot burner flames performed in a parametric fashion. Results from linear stability analysis are used to select the adequate parameter range to be investigated. The presence of DL instability is initially assessed using a recently proposed statistical marker related to flame morphology. The differences between stable and unstable flames are then statistically investigated, utilizing a single, laminar, DL-induced corrugation as a reference state. Such DL-induced effects are investigated at various turbulence intensities, in terms of local propagation, induced strain rate patterns and flow field as well as vorticity production and transformation. Using displacement speed as a measure of local propagation, no noticeable statistical difference is observed between stable and unstable flames while strain rate and vorticity patterns are shown to be largely influenced by the DL induced morphology. From the modeling point view, an enhancement of counter gradient type transport for turbulent scalar fluxes is observed for hydrodynamically unstable flames.