发表机构
The University of British Columbia（不列颠哥伦比亚大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
通过实验评估了用于湍流预混火焰LES的标量耗散率亚网格闭合模型，验证了其预测能力，并发现模型参数在大卡尔洛维茨数下与先前值一致，为扩展应用提供了依据。
AI 中文摘要
本文通过实验评估了用于湍流预混火焰大涡模拟（LES）的标量耗散率亚网格闭合模型。采用热线风速仪测量来表征背景湍流流动，并利用瑞利散射测量获取瞬时温度场，进而获得标量耗散率。燃料采用甲烷或富氢（体积占比40%）甲烷。卡尔洛维茨数在1.7至34.5之间变化。LES滤波尺寸从相应层流火焰热厚度的0.1倍变化至3.0倍。同时采用了高斯滤波和顶帽滤波两种方法。通过统计分析研究了测量所得、已解析和未解析的标量耗散率的特征，以及这些特征如何受归一化滤波尺寸、滤波类型和卡尔洛维茨数的影响。结果表明，在所考察的测试条件下，代数模型能够对法夫雷滤波、时间和空间平均的标量耗散率进行可接受的预测。实验测量用于深入了解代数模型中的一个关键参数。虽然对于小卡尔洛维茨数火焰，先前提出的模型参数值与本文测量值之间存在差异，但对于相对较大卡尔洛维茨数火焰，本文测量值与先前建议值取得了良好的一致性。尽管本实验研究中的火焰构型与以往数值研究存在差异，但这一发现在所考察的滤波尺寸和滤波方法下均保持一致。这促使未来研究评估该代数模型在扩展操作范围内模拟湍流预混火焰的应用。
英文摘要
A sub-grid closure of the scalar-dissipation rate for the Large Eddy Simulation (LES) of turbulent premixed flames is assessed experimentally. Hotwire anemometry is performed to characterize the background turbulent flow, and the Rayleigh scattering measurements are conducted to acquire instantaneous temperature fields, which are used to obtain the scalar dissipation rate. Either methane or hydrogen-enriched (40% by volume) methane is used as the fuel. The Karlovitz number varies between 1.7 and 34.5. The LES filter size is changed from 0.1 to 3.0 times the thermal thickness of the corresponding laminar flames. Both Gaussian and top-hat filtering methods are used. Statistical analyses are performed to investigate the characteristics of the measured, resolved, and unresolved scalar dissipation rate as well as how these are influenced by the normalized filter size, filter type, and the Karlovitz number. It is shown that the algebraic model allows for acceptable prediction of the Favre-filtered, temporally and spatially averaged scalar dissipation rate across the examined test conditions. The experimental measurements are used to gain insight into a key parameter used in the algebraic model. While differences between the previously proposed and our measured value of the model parameter for small Karlovitz number flames are reported, good agreement between our measured values and previously suggested values is obtained for relatively larger Karlovitz number flames. This finding is shown to be consistent across the examined filter sizes and filtering methods, despite the differences in the examined flame configuration of the present experimental study and those of past numerical investigations. This motivates future investigations to assess use of the algebraic model for simulating turbulent premixed flames with an extended range of operation.
