A posteriori testing of algebraic flame surface density models for LES
A posteriori testing of algebraic flame surface density models for LES
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DOI：
10.1080/13647830.2013.779388
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发表时间：
2013-06
影响因子：
1.3
通讯作者：
T. Ma;O. Stein;N. Chakraborty;Achim Kempf
中科院分区：
文献类型：
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作者：
T. Ma;O. Stein;N. Chakraborty;Achim Kempf
在预混燃烧的大涡模拟中，未知的过滤化学源项可以用广义火焰面密度来模拟，而广义火焰面密度可以用褶皱因子Ξ的代数模型来描述。本研究比较了各种模型的行为，首先通过一维分析考察了次网格湍流速度波动对Ξ的影响，并通过Oracle燃烧器(Nguyen，Bruel，and Reichstadt，Flow，Turbo and Comtation Vol.82[2009]，pp.155-183)和沃尔沃钻机(SJunnesson，Nelsson，and Max，激光测速仪，第3卷[1991年]，第83-90页；Sjunesson，Henrikson，and Löfström，AIAA Journal，第28卷[1992]，pp.)的LES比较了各种模型的行为。AIAA-92-3650)。对湍流粘性和网格分辨率等参数进行了敏感性研究。湍流火焰传播的一维统计分析表明，需要考虑进程变量的逆梯度传输，才能从基于代数FSD的闭合模拟中获得真实的火焰厚度。根据LES的预混燃烧图(Pitsch和Duchamp de Lagenust，《燃烧研究所学报》，第29卷[2002]，第2001-2008页)，发现两种燃烧器设置主要在起皱/波纹火焰区域内运行，这表明模型在其理想范围内运行。然后，通过比较速度统计数据来评估代数模型的性能，然后对Oracle燃烧器进行详细的误差分析。在测试的模型中，有四个被发现在实验中表现得相当好，这四个模型中的一个更胜一筹，因为它是最独立于网格的。对于沃尔沃钻机，更多的注意力放在温度数据的比较和识别不同型号之间火焰结构的变化上。研究发现，在先验的域名系统分析(Chakraborty和Klein，流体物理，第20卷[2008年]，085108页)中，有几个模型在很大程度上高估了甲骨文案例中的速度和体积的平均值，与沃尔沃试验台的实验观测结果有令人满意的一致性，而其他一些模型只能定量或定性地捕捉到沃尔沃试验台的实验数据。
In the application of Large Eddy Simulation (LES) to premixed combustion, the unknown filtered chemical source term can be modelled by the generalised flame surface density (FSD) using algebraic models for the wrinkling factor Ξ. The present study compares the behaviour of the various models by first examining the effect of sub-grid turbulent velocity fluctuation on Ξ through a one-dimensional analysis and by the LES of the ORACLES burner (Nguyen, Bruel, and Reichstadt, Flow, Turbulence and Combustion Vol. 82 [2009], pp. 155–183) and the Volvo Rig (Sjunnesson, Nelsson, and Max, Laser Anemometry, Vol. 3 [1991], pp. 83–90; Sjunnesson, Henrikson, and Löfström, AIAA Journal, Vol. 28 [1992], pp. AIAA–92–3650). Several sensitivity studies on parameters such as the turbulent viscosity and the grid resolution are also carried out. A statistically 1-D analysis of turbulent flame propagation reveals that counter gradient transport of the progress variable needs to be accounted for to obtain a realistic flame thickness from the simulations using algebraic FSD based closure. The two burner setups are found to operate mainly within the wrinkling/corrugated flamelet regime based on the premixed combustion diagram for LES (Pitsch and Duchamp de Lageneste, Proceedings of the Combustion Institute, Vol. 29 [2002], pp. 2001–2008) and this suggests that the models are operating within their ideal range. The performance of the algebraic models are then assessed by comparing velocity statistics, followed by a detailed error analysis for the ORACLES burner. Four of the tested models were found to perform reasonably well against experiments, and one of these four further excels in being the most grid-independent. For the Volvo Rig, more focus is placed upon the comparison of temperature data and identifying changes in flame structure amongst the different models. It is found that the few models which largely over-predict velocities in the ORACLES case and volume averaged in a previous a priori DNS analysis (Chakraborty and Klein, Physics of Fluids, Vol. 20 [2008], p. 085108), deliver satisfactory agreement with experimental observations in the Volvo Rig, whereas a few of the other models are only able to capture the experimental data of the Volvo Rig either quantitatively or qualitatively.