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arXiv 2602.21940physics.flu-dyn
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利用前传播公式进行湍流旋流稳定火焰的大涡模拟:解析火焰厚度的影响

Large eddy simulation of turbulent swirl-stabilized flames using the front propagation formulation: impact of the resolved flame thickness

National Key Laboratory of Fundamental Algorithms and Models for Engineering Numerical Simulation, Sichuan University(四川大学工程数值模拟基础算法与模型全国重点实验室);University of Chinese Academy of Sciences(中国科学院大学);Institute of Engineering Thermophysics, Chinese Academy of Sciences(中国科学院工程热物理研究所)

Ruochen Guo, Yunde Su, Yuewen Jiang

AI总结:

本文提出了一种扩展的前传播公式模型,用于大涡模拟旋流湍流预混火焰,研究解析火焰厚度对火焰动力学预测的影响。

摘要:

本文扩展了前传播公式(FPF)燃烧模型,用于旋流湍流预混火焰的大涡模拟(LES),并研究了解析火焰厚度对预测火焰动力学的影响。FPF方法旨在减轻未充分解析火焰的虚假传播,同时保持过滤火焰前沿的反应特性。在本研究中,该模型被扩展以考虑非绝热效应,并与改进的子滤波火焰速度估计相结合,以解决由于热释放效应对局部子滤波湍流造成的一致性问题。该扩展的FPF方法通过TECFLAM旋流稳定燃烧器的LES验证,结果与实验测量吻合良好。模拟显示,外切向层中涡旋结构的拉伸导致了被困火焰口袋的形成,这些口袋被识别为实验中观察到的二次温度峰值的物理机制。该现象的预测被证明在使用滤波尺寸建模子滤波火焰褶皱时,强烈依赖于解析火焰厚度。如果没有适当建模化学陡峭效应,解析火焰刷的厚度会被过度预测,导致火焰消耗率被低估。因此,火焰刷会脱离外切向层,导致无法捕捉火焰口袋及其相关的二次温度峰值。

英文摘要:

This work extends the front propagation formulation (FPF) combustion model to large eddy simulation (LES) of swirl-stabilized turbulent premixed flames and investigates the effects of resolved flame thickness on the predicted flame dynamics. The FPF method is designed to mitigate the spurious propagation of under-resolved flames while preserving the reaction characteristics of filtered flame fronts. In this study, the model is extended to account for non-adiabatic effects and is coupled with an improved sub-filter flame speed estimation that resolves the inconsistency arising from heat-release effects on local sub-filter turbulence. The performance of the extended FPF method is validated by LES of the TECFLAM swirl-stabilized burner, where the results agree well with experimental measurements. The simulations reveal that the stretching of vortical structures in the outer shear layer leads to the formation of trapped flame pockets, which are identified as the physical mechanism responsible for the secondary temperature peaks observed in the experiment. The prediction of this phenomenon is shown to be strongly dependent on the resolved flame thickness, when the filter size is used for modeling sub-filter flame wrinklings. Without proper modeling of the chemical steepening effects, the thickness of the resolved flame brush is over-predicted, causing the flame consumption rate to be under-estimated. Consequently, the flame brush detaches from the outer shear layer, resulting in a failure to capture the flame pockets and the associated secondary temperature peaks.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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