Studies of autoignition-assisted nonpremixed cool flames
Studies of autoignition-assisted nonpremixed cool flames
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DOI：
10.1016/j.proci.2020.06.379
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发表时间：
2020-09
期刊：
影响因子：
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通讯作者：
Y. Murakami;C. Reuter;O. Yehia;Y. Ju
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文献类型：
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作者：
Y. Murakami;C. Reuter;O. Yehia;Y. Ju
在层流逆流和湍流喷射火焰配置中研究了乙醚 (DEE) 自燃辅助非预混冷火焰。首先，使用详细的动力学模型测量和模拟稀释 DEE 的层流非预混合冷火焰的点火和熄灭极限。层流火焰测量用于验证动力学模型并指导湍流火焰测量。结果表明，低于临界混合物条件，对于高温和稀混合物，冷焰熄灭极限和低温着火极限合并，导致自燃辅助冷焰稳定而无滞后。根据层流火焰实验的结果，使用并流轴对称反应器辅助湍流 (CARAT) 燃烧器建立了自燃辅助湍流提升冷火焰。使用甲醛平面激光诱导荧光来量化湍流冷火焰的升空高度。基于与自燃辅助提升热火焰的类比，提出了一种相关性，使得自燃辅助冷火焰提升高度与流速和第一阶段点火延迟时间的平方的乘积成比例。使用这种缩放，我们证明了最准确地预测层流火焰点火和熄灭极限的动力学机制也最好地预测了湍流冷火焰升空高度。
Autoignition-assisted nonpremixed cool flames of diethyl ether (DEE) are investigated in both laminar counterflow and turbulent jet flame configurations. First, the ignition and extinction limits of laminar nonpremixed cool flames of diluted DEE are measured and simulated using detailed kinetic models. The laminar flame measurements are used to validate the kinetic models and guide the turbulent flame measurements. The results show that, below a critical mixture condition, for elevated temperature and dilute mixtures, the cool flame extinction limit and the low-temperature ignition limit merge, leading to autoignition-assisted cool flame stabilization without hysteresis. Based on the findings from the laminar flame experiments, autoignition-assisted turbulent lifted cool flames are established using a Co-flow Axisymmetric Reactor-Assisted Turbulent (CARAT) burner. The lift-off heights of the turbulent cool flames are quantified using formaldehyde planar laser-induced fluorescence. Based on an analogy with autoignition-assisted lifted hot flames, a correlation is proposed such that the autoignition-assisted cool flame lift-off height scales with the product of the flow velocity and the square of the first-stage ignition delay time. Using this scaling, we demonstrate that the kinetic mechanism that most accurately predicts the laminar flame ignition and extinction limits also best predicts the turbulent cool flame lift-off height.