Streamline segment statistics of premixed flames with nonunity Lewis numbers.
Streamline segment statistics of premixed flames with nonunity Lewis numbers.
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使用非统一路易斯数简化预混合火焰的分段统计。
DOI：
10.1103/physreve.89.033015
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
Chakraborty N
中科院分区：
文献类型：
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作者：
Chakraborty N
火焰和周围流体运动的相互作用在湍流燃烧的基本理解中具有中心重要性。它在这里表明，这种相互作用可以表示使用流线段分析，这是以前应用于非反应性湍流。本工作的重点是在薄反应区制度的预混火焰的整体刘易斯数（Le）的流线段统计的影响。一个直接的数值模拟数据库的自由传播的薄反应区制度火焰与乐范围从到是用来证明，乐有显着的影响的流线段的特征，如曲线长度，在两个极值点的速度幅值的差异，以及它们与当地的火焰曲率的相关性。膨胀率，火焰法向加速度，和火焰产生的湍流与减少乐的加强是主要负责这些观察到的效果。流线段长度的概率密度函数（PDF）的表达式，最初开发的nonreacting湍流，捕获的定性行为湍流预混火焰在薄反应区制度的广泛的乐值。分析和比较了未加权和密度加权速度矢量在两个极值点处的流线长度和速度幅值差之间的联合概率密度函数。详细的解释提供了所观察到的流线段的拓扑行为的差异，以响应全球乐。
The interaction of flame and surrounding fluid motion is of central importance in the fundamental understanding of turbulent combustion. It is demonstrated here that this interaction can be represented using streamline segment analysis, which was previously applied in nonreactive turbulence. The present work focuses on the effects of the global Lewis number (Le) on streamline segment statistics in premixed flames in the thin-reaction-zones regime. A direct numerical simulation database of freely propagating thin-reaction-zones regime flames with Le ranging fromtois used to demonstrate that Le has significant influences on the characteristic features of the streamline segment, such as the curve length, the difference in the velocity magnitude at two extremal points, and their correlations with the local flame curvature. The strengthenings of the dilatation rate, flame normal acceleration, and flame-generated turbulence with decreasing Le are principally responsible for these observed effects. An expression for the probability density function (pdf) of the streamline segment length, originally developed for nonreacting turbulent flows, captures the qualitative behavior for turbulent premixed flames in the thin-reaction-zones regime for a wide range of Le values. The joint pdfs between the streamline length and the difference in the velocity magnitude at two extremal points for both unweighted and density-weighted velocity vectors are analyzed and compared. Detailed explanations are provided for the observed differences in the topological behaviors of the streamline segment in response to the global Le.