Hydrodynamic and thermodiffusive instability effects on the evolution of laminar planar lean premixed hydrogen flames
Hydrodynamic and thermodiffusive instability effects on the evolution of laminar planar lean premixed hydrogen flames
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DOI：
10.1017/jfm.2012.136
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发表时间：
2012-05
影响因子：
3.7
通讯作者：
C. Altantzis;C. Frouzakis;A. Tomboulides;M. Matalon;K. Boulouchos
中科院分区：
文献类型：
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作者：
C. Altantzis;C. Frouzakis;A. Tomboulides;M. Matalon;K. Boulouchos
摘要 使用单步化学和详细传输的数值模拟来研究二维通道状域中的预混合氢气/空气火焰，沿水平边界具有周期性边界条件作为域高度的函数。考虑了单位路易斯数（仅出现流体动力学不稳定性）和亚单位路易斯数（其中火焰传播受到流体动力学和热扩散不稳定性的综合影响的强烈影响）。模拟旨在研究叠加在平面火焰前锋上的扰动的初始线性增长以及长期非线性演化。从模拟中提取了表征线性状态的生长速率和扰动波长之间的色散关系，并与线性稳定性理论进行了比较。非线性演化过程中观察到的动力学很大程度上取决于域大小和路易斯数。正如理论所预测的那样，单位路易斯数火焰被发现形成单个尖点结构，该结构以恒定速度传播不变。亚基路易斯数火焰的长期动态包括稳定的细胞传播、横向火焰运动、振荡以及规则和混沌的细胞分裂和合并。
Abstract Numerical simulations with single-step chemistry and detailed transport are used to study premixed hydrogen/air flames in two-dimensional channel-like domains with periodic boundary conditions along the horizontal boundaries as a function of the domain height. Both unity Lewis number, where only hydrodynamic instability appears, and subunity Lewis number, where the flame propagation is strongly affected by the combined effect of hydrodynamic and thermodiffusive instabilities are considered. The simulations aim at studying the initial linear growth of perturbations superimposed on the planar flame front as well as the long-term nonlinear evolution. The dispersion relation between the growth rate and the wavelength of the perturbation characterizing the linear regime is extracted from the simulations and compared with linear stability theory. The dynamics observed during the nonlinear evolution depend strongly on the domain size and on the Lewis number. As predicted by the theory, unity Lewis number flames are found to form a single cusp structure which propagates unchanged with constant speed. The long-term dynamics of the subunity Lewis number flames include steady cell propagation, lateral flame movement, oscillations and regular as well as chaotic cell splitting and merging.