Effect of sub-grid wrinkling factor modelling on the large eddy simulation of turbulent stratified combustion
Effect of sub-grid wrinkling factor modelling on the large eddy simulation of turbulent stratified combustion
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DOI：
10.1080/13647830.2021.1962546
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发表时间：
2021-07
影响因子：
1.3
通讯作者：
E. Inanc;Achim Kempf;N. Chakraborty
中科院分区：
文献类型：
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作者：
E. Inanc;Achim Kempf;N. Chakraborty
采用大涡模拟(LES)和人工增厚火焰方法，对剑桥分层火焰的不同火焰效率函数(起皱系数)模型进行了比较和检验。测试了不同的数值离散化和外部截止长度的定义，因为存在着对结果有很大影响的不同做法。之所以选择剑桥实验，是因为它的雷诺数超过11,500，而且分层火焰在下游有很强的褶皱，这使得它对于湍流(分层)燃烧模型来说是一个具有挑战性的结构。为了分析褶皱因子对大涡模拟的影响，用四个褶皱因子闭包来模拟亚格子水平物理，它们显式依赖于分解变量的代数函数。已经提出了许多这样的模型，并成功地进行了测试--但通常是针对完全预混的火焰，使用特定的离散化和截止长度或过滤器宽度的定义。本文表明，即使对于分层燃烧，只要使用正确的截止长度定义，并在较小程度上采用适当的离散化方法，所测试的模型也能很好地执行。
Different flame efficiency function (wrinkling factor) models are compared and tested for the Cambridge stratified flame using Large Eddy Simulations (LES) with an artificially thickened flame approach. Different numerical discretisations and definitions of the outer cut-off length are tested, as different practices exist that can have a strong impact on the results. The Cambridge experiment is chosen since it exhibits a Reynolds number of more than 11,500 and the stratified flame is strongly wrinkled further downstream, making it a challenging configuration for the turbulent (stratified) combustion modelling. The sub-grid level physics have been modelled by four wrinkling factor closures, which rely explicitly on algebraic functions of resolved variables, to analyse the influence of wrinkling factor modelling on the predictions of LES. Many such models have been proposed and were tested successfully – but typically for perfectly premixed flames, using specific discretisations and definitions of the cut-off length or filter width. The present paper shows that the models tested perform well even for stratified combustion, provided that the correct definition for the cut-off length is used, and to a lesser extent, suitable discretisation methodologies are employed.