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首页> 外文期刊>International Journal of Heat and Mass Transfer >On the individual importance of temperature and concentration fluctuations in the turbulence-radiation interaction in pool fires
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On the individual importance of temperature and concentration fluctuations in the turbulence-radiation interaction in pool fires

机译：在池火中湍流-辐射相互作用中温度和浓度波动的个体重要性

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This paper presents a study of resolved-scale turbulence-radiation interaction (TRI) effects in large-scale methanol and ethanol pool fires. A broad investigation of the magnitude of the phenomenon when assuming the participating medium as gray or as non-gray is first conducted, followed by an analysis of the individual importance of turbulent fluctuations of temperature and species concentrations in the prediction of the mean radiation field. For these purposes, transient data generated by large eddy simulation are compared to results of independent radiative transfer calculations initialized with mean temperature and medium composition fields. A new methodology is proposed to isolate the influence of each fluctuating scalar on the overall TRI. In all test cases, turbulence-radiation interaction was found to increase the region of radiation loss, leading to differences between 60% and 80% in the radiant fraction of the flame compared to solutions neglecting turbulent fluctuations. When treating the media as non-gray, TRI effects were globally more significant, even though in some parts of the domain simulations employing the gray assumption yielded larger deviations in the mean radiative heat source due to TRI. By isolating the contributions of fluctuations of temperature and fluctuations of species concentrations, the latter resulted in mean radiation fields very similar to the ones obtained by neglecting all scalar fluctuations, while the former, although being closer to the solution considering full TRI effects, still showed differences as high as 60% relative to that solution. These findings indicate that temperature fluctuations are more important to the turbulence-radiation interaction phenomenon, but fluctuations in medium composition need to be taken into account in order to obtain reliable predictions of the mean radiative heat transfer. (C) 2019 Elsevier Ltd. All rights reserved.
机译：本文提出了在大规模甲醇和乙醇池火中分辨尺度湍流-辐射相互作用（TRI）效应的研究。首先，假设参与介质为灰色或非灰色时，对现象的强度进行了广泛的研究，然后分析了温度和物种浓度的湍流波动对预测平均辐射场的重要性。为此，将由大涡流模拟生成的瞬态数据与用平均温度和介质成分场初始化的独立辐射传输计算的结果进行比较。提出了一种新的方法来隔离每个波动标量对整体TRI的影响。在所有测试案例中，都发现湍流-辐射相互作用会增加辐射损失的区域，与忽略湍流波动的解决方案相比，导致火焰辐射分数的差异介于60％和80％之间。当将介质视为非灰色介质时，即使在使用灰色假设的域模拟的某些部分中，由于TRI而导致平均辐射热源的偏差较大，TRI效果在全局上也更为显着。通过隔离温度波动和物种浓度波动的贡献，后者产生的平均辐射场与通过忽略所有标量波动获得的平均辐射场非常相似，而前者虽然更接近于考虑到完全TRI效应的解，但仍显示出相对于该解决方案的差异高达60％。这些发现表明温度波动对湍流-辐射相互作用现象更为重要，但是为了获得对平均辐射热传递的可靠预测，需要考虑介质成分的波动。 （C）2019 Elsevier Ltd.保留所有权利。

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