A flame particle tracking analysis of turbulence–chemistry interaction in hydrogen–air premixed flames
A flame particle tracking analysis of turbulence–chemistry interaction in hydrogen–air premixed flames
复制标题
氢-空气预混火焰中湍流-化学相互作用的火焰粒子追踪分析
DOI：
10.1016/j.combustflame.2015.09.033
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发表时间：
2016
影响因子：
4.4
通讯作者：
H. Im
中科院分区：
文献类型：
--
作者：
Harshavardhana A. Uranakara;Swetaprovo Chaudhuri;H. Dave;Paul G. Arias;H. Im
湍流、分子输运和能量输运的相互作用，再加上化学作用，在强烈湍流预混火焰的火焰表面几何形状、传播、湮灭和局部熄灭/重燃特性的演变中起着至关重要的作用。本研究旨在了解这些相互作用如何影响贫氢-空气预混湍流火焰的火焰表面湮灭。在不同的参数条件下对氢-空气火焰进行了直接数值模拟，详细分析了氢-空气火焰的反应机理和输运特性。火焰粒子跟踪（FPT）技术用于跟踪特定的火焰表面段。考虑了温度等值面局部位移火焰速度（Sd）的解析表达式，并确定了不同湍流-火焰相互作用条件下输运、化学和运动学对位移火焰速度的贡献。在一般情况下，位移火焰速度的火焰粒子被发现随时间的推移，考虑所有的条件。这是因为，最终所有的火焰表面和他们的居民火焰粒子接近湮灭的反应物岛的形成结束时的拉伸和折叠过程引起的湍流。使用FPT获得的主曲率随时间变化的统计数据表明，这些岛屿平均是椭圆形的，包围着新鲜的反应物。进一步的研究表明，增加的负曲率的火焰表面和最终均匀化的温度梯度，因为这些反应物岛收缩，由于火焰传播和湍流混合引起的增加。最后，规范化的，平均的，位移火焰速度与拉伸Karlovitz数的演变被发现崩溃在一个窄带上，这表明一个统一的描述火焰速度对拉伸率的依赖可能是可能的拉格朗日描述。
Interactions of turbulence, molecular transport, and energy transport, coupled with chemistry play a crucial role in the evolution of flame surface geometry, propagation, annihilation, and local extinction/re-ignition characteristics of intensely turbulent premixed flames. This study seeks to understand how these interactions affect flame surface annihilation of lean hydrogen–air premixed turbulent flames. Direct numerical simulations (DNSs) are conducted at different parametric conditions with a detailed reaction mechanism and transport properties for hydrogen–air flames. Flame particle tracking (FPT) technique is used to follow specific flame surface segments. An analytical expression for the local displacement flame speed (Sd) of a temperature isosurface is considered, and the contributions of transport, chemistry, and kinematics on the displacement flame speed at different turbulence-flame interaction conditions are identified. In general, the displacement flame speed for the flame particles is found to increase with time for all conditions considered. This is because, eventually all flame surfaces and their resident flame particles approach annihilation by reactant island formation at the end of stretching and folding processes induced by turbulence. Statistics of principal curvature evolving in time, obtained using FPT, suggest that these islands are ellipsoidal on average enclosing fresh reactants. Further examinations show that the increase inSdis caused by the increased negative curvature of the flame surface and eventual homogenization of temperature gradients as these reactant islands shrink due to flame propagation and turbulent mixing. Finally, the evolution of the normalized, averaged, displacement flame speed vs. stretch Karlovitz number are found to collapse on a narrow band, suggesting that a unified description of flame speed dependence on stretch rate may be possible in the Lagrangian description.
影响因子：
4.6
作者：
N. Chakraborty;N. Swaminathan
通讯作者：
N. Chakraborty;N. Swaminathan
影响因子：
4.6
作者：
Chakraborty, N.;Swaminathan, N.
通讯作者：
Swaminathan, N.