Prediction of local extinctions in piloted jet flames with inhomogeneous inlets using unstrained flamelets
Prediction of local extinctions in piloted jet flames with inhomogeneous inlets using unstrained flamelets
复制标题
使用无应变小火焰预测具有不均匀入口的先导喷射火焰中的局部熄灭
DOI：
10.1016/j.combustflame.2019.11.007
复制
发表时间：
2020
影响因子：
4.4
通讯作者：
Chen Z
中科院分区：
文献类型：
--
作者：
Chen Z
多区域湍流燃烧模型仍然具有挑战性，并在本研究中探索了局部灭绝的发生。本文采用基于无应变预混火焰的部分预混模型，研究了非均匀进气道引导射流火焰结构。三种不同的情况下进行了模拟，不同的体积平均速度，分别约为50%，70%和90%的实验测得的吹脱速度。当射流速度接近吹出极限时，沿着火焰表面开始发生局部喷射，因此这些火焰从建模的角度来看是具有挑战性的。两种不同的数值方法，涉及缩放和未缩放的进展变量分别进行了比较，阐明他们的能力和局限性，以预测局部湍流，并处理在先导/同向流接口的三流问题。这种预测的关键建模细节表示和讨论。LES的结果进行了系统的比较，在文献中的三个火焰的两组实验测量。还借助LES结果讨论了两个实验数据集中观察到的差异。虽然这两种方法显示出有希望的协议的火焰统计，缩放的进展变量的方法更好地预测当地的火灾。未缩放的方法表明，自然处理的三个流的问题，而无需额外的治疗试点/coflow接口，这是所需的缩放方法。此外，计算的标量耗散率的混合物分数的测量显示良好的协议的条件下进行比较。这进一步表明，如果捕获了正确的标量混合及其耗散，则可以使用无应变火焰来预测局部湍流。
Multi-regime turbulent combustion modelling remains challenging and is explored with occurrence of local extinction in this study. A partially premixed model based on unstrained premixed flamelets is used in this work to investigate a piloted jet flame configuration with inhomogeneous inlets. Three different cases are simulated, which differ in the bulk mean velocity that amounts respectively to about 50%, 70% and 90% of the blow off velocity measured experimentally. As the jet velocity approaches the blow off limit, local extinctions start to occur along the flame surface and thus these flames are challenging from a modelling prospective. Two different numerical approaches, involving scaled and unscaled progress variable respectively, are compared to elucidate their abilities and limitations to predict local extinctions and to deal with the three-stream problem at the pilot/coflow interface. The key modelling details for such predictions are indicated and discussed. LES results are systematically compared to two sets of experimental measurements available in the literature for the three flames. The differences observed in the two experimental datasets are also discussed with the help of LES results. Although both approaches show promising agreement for the flame statistics, the scaled progress variable approach better predicts the local extinctions. The unscaled approach shows to naturally handle the three-stream problem without additional treatment for the pilot/coflow interface, which is required for the scaled approach. Furthermore, computed scalar dissipation rate of mixture fraction is compared with the measurements showing good agreement for the conditions investigated. This further suggests that local extinctions can be predicted using unstrained flamelets if the correct scalar mixing and its dissipation are captured.
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影响因子：
1.9
作者：
I. Langella;N. Swaminathan;F. Williams;J. Furukawa
通讯作者：
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DOI：
10.1016/j.proci.2014.05.144
发表时间：
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期刊：
--
影响因子：
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影响因子：
4.4
作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
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DOI：
10.17863/cam.36912
发表时间：
2019
期刊：
--
影响因子：
--
作者：
Chen Z
通讯作者：
Chen Z