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Generalised correlations of blow-off and flame quenching for sub-sonic and choked jet flames

机译：亚音速和cho流喷射火焰的起爆和火焰淬灭的广义相关性

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Dimensionless groups suggested by the mathematical modelling of subsonic fuel jet flames, and extensive experimental data, have been reasonably successsful in correlating dimensionles flame heights and flame lift-off distances in terms of a dimensionless flow number. This approach is extended to the more exacting correlations that define regimes of flame quenching, blow-off, and lifted flames. Experimental data from these diverse sources are analysed, and the bounds of these regimes are expressed in terms of the critical minimum jet pipe diameter to avoid blow-off, normalised by the laminar flame thickness for the maximum burning velocity mixture, and the flow number. The regimes extend from low Reynolds number laminar flows in hypodermic tubes to high Reynolds number choked flows, with supersonic shocks. Data are well corrrelated in the subsonic regime for a range of hydrocarbon gases, in which critical pipe diameters for the avoidance of blow-off increase with flow number. Matters are more complex in the extended choked flow regime, in which there are less data. This regime of supersonic flow and shock waves is one of improved fuel/air mixing and enhanced reactivity, to such an extent that the critical pipe diameter, after reaching a maximum, decreases. Data are presented in this regime, and indeed over the full range of conditions, for methane, propane and hydrogen jet flames. Hydrogen exhibits more reactive characteristics than the hydrocarbons. In terms of the correlating parameters, whereas laminar flame thickness is related to that of the non-reacting preheat zone, such a zone is difficult to define with hydrogen, as a consequence of the upstream diffusion of H atoms, and this aspect is discusssed. (C) 2017 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
机译：由亚音速燃料喷射火焰的数学模型建议的无量纲组和广泛的实验数据，在无量纲流量方面，已成功地关联了无量纲的火焰高度和火焰升起距离。该方法扩展到了更严格的相关性，这些相关性定义了火焰淬灭，吹除和提升火焰的状态。分析了来自这些不同来源的实验数据，并根据避免喷出的临界最小喷射管直径（通过最大燃烧速度混合物的层流火焰厚度和流量标准化）来表示这些方案的界限。范围从皮下注射管中的低雷诺数层流扩展到具有超音速冲击的高雷诺数cho流。在亚音速状态下，一系列烃类气体的数据具有很好的相关性，其中避免吹脱的临界管径随流量增加。在扩展的ked流状态下，情况变得更加复杂，在这种情况下，数据更少。超声波流和冲击波的这种状态是改善的燃料/空气混合和增强的反应性中的一种，以至于在达到最大值后，临界管径减小。在甲烷，丙烷和氢气喷射火焰的这种情况下，甚至在整个条件范围内，都提供了数据。氢比烃表现出更多的反应特性。就相关参数而言，虽然层流火焰厚度与非反应预热区的层厚有关，但由于H原子的上游扩散，难以用氢限定该区，并且对此方面进行了讨论。 （C）2017燃烧研究所。由Elsevier Inc.出版。保留所有权利。

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