Cellular Flame Instabilities
Cellular Flame Instabilities
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细胞火焰不稳定性
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
R. Mumby
中科院分区：
文献类型：
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作者：
D. Bradley;M. Lawes;R. Mumby
爆发球形层流火焰中的Darrieus朗道不稳定性和热扩散不稳定性的开始由Peclet数Pecl的值标记，Pecl取决于Markstein数。在球形爆炸弹中，在0.5和1.0 MPa下测量了许多不同混合物的Pecl值。这些值作为火焰速度Markstein数，Mab的函数，它被发现，既不是不同的压力，也不是不同的混合物有很大的影响，这种相关性。从甲烷/空气和丙烷/空气的大规模大气爆炸得到的值也密切遵循相同的相关性。这表明高压实验室爆炸的数据可能被用来预测大规模大气爆炸的影响。其他工作者的发现遵循相同的趋势，尽管不同的详细结果可能来自不同的Markstein数定义和不同的测量技术。由于必要的最小拉伸率对稳定火焰的重要性，这种类型的不稳定性的开始的更合乎逻辑和基本的标准是基于火焰拉伸率的标准，例如临界Karlovitz拉伸因子Kcl。因此，相关性也以Kcl而不是Pecl表示。当Masr变得非常消极时，稳定的机制就会严重削弱。
The onset of Darrieus Landau and thermo-diffusive instabilities in an exploding spherical laminar flame is marked by the value of the Peclet number, Pecl, which is dependent upon the Markstein number. Values of Pecl for a number of different mixtures have been measured at 0.5 and 1.0 MPa in a spherical explosion bomb. These values are presented as a function of the flame speed Markstein number, Mab, and it is found that neither different pressures nor the different mixtures have a great effect on this correlation. Values derived from much larger scale atmospheric explosions of methane/air and propane/air also closely follow the same correlation. This suggests data from high pressure laboratory explosions might be used to predict the effects of large scale atmospheric explosions. Findings from other workers follow the same trend, although different detailed results can arise from both different definitions of Markstein number, and different measurement techniques. Because of the importance of a necessary minimal stretch rate to stabilise a flame, a more logical and fundamental criterion for the onset of this type of instability is one based on the flame stretch rate, such as a critical Karlovitz stretch factor, Kcl. As a result, the correlations are also expressed in terms of Kcl, instead of Pecl. As Masr becomes highly negative, the regime of stability is severely reduced.