Analytic prediction of unconfined boundary layer flashback limits in premixed hydrogen-air flames
Analytic prediction of unconfined boundary layer flashback limits in premixed hydrogen-air flames
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DOI：
10.1080/13647830.2016.1240832
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发表时间：
2017-01-01
影响因子：
1.3
通讯作者：
Sattelmayer, Thomas
中科院分区：
文献类型：
--
作者：
Hoferichter, Vera;Hirsch, Christoph;Sattelmayer, Thomas
火焰回火是预混燃烧中的一大难题。因此，预测防止边界层回火的最小流速具有很高的技术价值。本文提出了一种预测通道和管式燃烧器边界层回火极限的解析方法。该模型反映了实验观察到的闪回机制，并由局部和全局分析组成。在局部分析的基础上，得到了回火起爆时的气流速度与火焰角和局部湍流燃烧速度的关系。局部湍流燃烧速度是根据作者在早期出版物中提出的关于管道受限火焰的边界层回火极限的预测模型来计算的。这确保了两种模型的一致性。稳定火焰在回火状态下的火焰角可以通过多种方法得到。在这项研究中，应用了一种基于全局质量守恒的方法，并利用通道燃烧器试验台在环境条件下的米氏散射图像进行了验证。将预测的回火极限与实验结果和预热管式燃烧器实验的文献数据进行了比较。最后，给出了一种考虑燃烧器出口温度影响的方法，并用该方法解释了文献报道的不同燃烧器结构所得到的回火极限的差异。
Flame flashback is a major challenge in premixed combustion. Hence, the prediction of the minimum flow velocity to prevent boundary layer flashback is of high technical interest. This paper presents an analytic approach to predicting boundary layer flashback limits for channel and tube burners. The model reflects the experimentally observed flashback mechanism and consists of a local and global analysis. Based on the local analysis, the flow velocity at flashback initiation is obtained depending on flame angle and local turbulent burning velocity. The local turbulent burning velocity is calculated in accordance with a predictive model for boundary layer flashback limits of duct-confined flames presented by the authors in an earlier publication. This ensures consistency of both models. The flame angle of the stable flame near flashback conditions can be obtained by various methods. In this study, an approach based on global mass conservation is applied and is validated using Mie-scattering images from a channel burner test rig at ambient conditions. The predicted flashback limits are compared to experimental results and to literature data from preheated tube burner experiments. Finally, a method for including the effect of burner exit temperature is demonstrated and used to explain the discrepancies in flashback limits obtained from different burner configurations reported in the literature.