A Fractal Dynamic SGS Combustion Model for Large Eddy Simulation of Turbulent Premixed Flames
A Fractal Dynamic SGS Combustion Model for Large Eddy Simulation of Turbulent Premixed Flames
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DOI：
10.1080/00102202.2016.1195820
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发表时间：
2016-06
影响因子：
1.9
通讯作者：
K. Hiraoka;Y. Minamoto;M. Shimura;Y. Naka;N. Fukushima;M. Tanahashi
中科院分区：
文献类型：
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作者：
K. Hiraoka;Y. Minamoto;M. Shimura;Y. Naka;N. Fukushima;M. Tanahashi
摘要采用直接数值模拟方法研究了平面射流火焰的分形特征，并对分形动态亚网格尺度（FDSGS）燃烧模型进行了评价。DNS的结果表明，火焰表面的分形维数增加的下游距离，和使用三维盒计数法计算的分形维数达到约2.54的区域，湍流发展的平均剪切。FDSGS燃烧模型采用的内截断表示法可用于复杂燃烧问题的大涡模拟。静态试验表明，在FDSGS燃烧模型中应用的程序充分预测的分形维数，柯尔莫哥洛夫长度尺度，和火焰表面积，尽管存在较强的平均剪切。动态模型评估也进行了一系列LES使用FDSGS和其他燃烧模型。在动态试验中，从LES与FDSGS燃烧模型获得的平均温度分布和反应进程变量波动在横向方向上的变化的峰值位置显示出良好的一致性与过滤DNS场。本评估还表明，FDSGS燃烧建模方法的优势之一是，该模型不需要SGS湍流速度波动，因为该量的建模既不适用于均匀湍流，也不适用于湍流剪切流。
ABSTRACT Direct numerical simulation of a turbulent hydrogen-air premixed plane jet flame is performed to investigate fractal characteristics and to evaluate the fractal dynamic subgrid scale (FDSGS) combustion model. The DNS results show that the fractal dimension of flame surfaces increases with the downstream distance, and the fractal dimension computed using a 3D box-counting method reaches about 2.54 in the region where turbulence is developed by mean shear. An inner cutoff representation employed in the FDSGS combustion model could be used in large eddy simulations (LES) of complicated combustion problems. Static tests show that the procedure applied in the FDSGS combustion model adequately predicts the fractal dimension, Kolmogorov length scale, and flame surface area despite the presence of strong mean shear. Dynamic model evaluations are also carried out by conducting a series of LES using the FDSGS and other combustion models. In the dynamic tests, the mean temperature distributions and peak positions of variations of a reaction progress variable fluctuation in the transverse direction obtained from the LES with the FDSGS combustion model show good agreement with the filtered DNS fields. The present evaluation also revealed that one of the strengths in the FDSGS combustion modeling approach is that the model does not require SGS turbulent velocity fluctuation, since modeling of this quantity is straightforward for neither homogeneous turbulence nor the turbulent shear flows.