标题： 湍流预混火焰前沿的分形尺度：应用于LES 显示英文标题

标题： Fractal scaling of turbulent premixed flame fronts: application to LES

摘要： 湍流预混火焰前沿的分形尺度特性已被研究并用于大涡模拟框架中的亚网格尺度建模。 由于这种薄反应前沿的宽度无法在大涡模拟的粗网格中解析，因此考虑了体积内包含的皱褶火焰表面的程度。 通过“皱褶因子”估算未解析火焰前沿的数量，该因子取决于适当分形维数的定义以及分形尺度消失的尺度，即内部截断长度{\epsilon }i。 在此背景下，本研究考虑了不同湍流预混火焰状态下的实验室实验和一步反应直接数值模拟。 发现分形维数基本恒定，并远低于被动标量前沿的典型值。 内部截断长度在所考虑的范围内与科氏耗散尺度显示出清晰的尺度关系。 这些特征被用于进行大涡模拟。 在中等雷诺数下将大涡模拟与相应的直接数值模拟进行比较，并在较高雷诺数下与实验数据进行比较，发现模型性能良好。 显示英文摘要

摘要： The fractal scaling properties of turbulent premixed flame fronts have been investigated and considered for modelling sub-grid scales in the Large-Eddy-Simulation framework. Since the width of such thin reaction fronts cannot be resolved into the coarse mesh of LES, the extent of wrinkled flame surface contained in a volume is taken into account. The amount of unresolved flame front is estimated via the "wrinkling facto" that depends on the definition of a suitable fractal dimension and the scale at which the fractal scaling is lost, the inner cut-off length {\epsilon}i. In this context, the present study considers laboratory experiments and one-step reaction DNS of turbulent premixed jet flames in different regimes of turbulent premixed flames. Fractal dimension is found to be substantially constant and well below that typical of passive scalar fronts. The inner cut-off length shows a clear scaling with the dissipative scale of Kolmogorov for the regimes here considered. These features have been exploited performing Large Eddy Simulations. Good model performance has been found comparing the LES against a corresponding DNS at moderate Reynolds number and experimental data at higher Reynolds numbers.