A localized thickened flame model for simulations of flame propagation and autoignition under elevated pressure conditions
A localized thickened flame model for simulations of flame propagation and autoignition under elevated pressure conditions
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DOI：
10.1016/j.proci.2020.06.063
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发表时间：
2020-09
期刊：
影响因子：
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通讯作者：
H. Terashima;Yutaka Hanada;S. Kawai
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文献类型：
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作者：
H. Terashima;Yutaka Hanada;S. Kawai
本研究提出了一个局部增厚火焰（LTF）模型的火焰传播和自燃定时的准确预测。由于薄火焰结构的空间滤波控制方程中出现的未解析尺度项被构造在层流火焰速度保持的物理约束下。一个高阶导数被引入到动态本地化的LTF在未解决的传播火焰的区域的影响。该模型还被设计成使得对于所使用的任何网格尺寸，通过相同数量的网格点来解析增厚的火焰。因此，模型中用户指定的常数不需要根据所采用的网格大小进行调整。层流火焰传播问题被用来验证所提出的LTF模型的性能，并确定适当的值的用户指定的常数。使用一维定容反应器的结果表明，LTF成功地捕捉到准确的火焰传播行为在高压条件下，而不影响最终气体自燃定时，即使在相对粗糙的网格分辨率。在LTF中的高阶导数用作用于检测在升高的压力条件下的细化火焰的动态参数。
The present study proposes a localized thickened flame (LTF) model for the accurate prediction of flame propagation and autoignition timing. The unresolved-scale terms appeared in spatially-filtered governing equations due to thin flame structures are constructed under a physical constraint in which laminar flame speed is maintained. A high-order derivative is introduced to dynamically localize the effects of the LTF in the regions of unresolved propagating flame. The model is also designed such that the thickened flame is resolved by the same number of grid points for any grid size used. Therefore, a user-specified constant in the model does not need to be adjusted depending on the employed grid size. Laminar flame propagation problems are used to validate the performance of the proposed LTF model and determine the appropriate value of the user-specified constant. The results using a one-dimensional constant-volume reactor demonstrate that the LTF successfully captures the accurate flame propagation behaviors under elevated pressure conditions, while not affecting the end-gas autoignition timing, even on relatively coarse grid resolutions. The high-order derivative in the LTF serves as a dynamic parameter for detecting the thinning flame under elevated pressure conditions.