Imaging measurements and LES-CMC modeling of a partially-premixed turbulent dimethyl ether/air jet flame
Imaging measurements and LES-CMC modeling of a partially-premixed turbulent dimethyl ether/air jet flame
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DOI：
10.1016/j.proci.2014.06.042
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发表时间：
2015
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影响因子：
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通讯作者：
B. Coriton;Masoomeh Zendehdel;S. Ukai;A. Kronenburg;O. Stein;S. Im;M. Gamba;Jonathan H. Frank
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文献类型：
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作者：
B. Coriton;Masoomeh Zendehdel;S. Ukai;A. Kronenburg;O. Stein;S. Im;M. Gamba;Jonathan H. Frank
湍流二甲醚（DME）射流火焰提供了一个规范的火焰几何研究含氧燃料的连续性火焰的相互作用，并为这些相互作用的预测模型。二甲醚/空气火焰精确模型的建立将为更复杂的含氧燃料的研究奠定基础。我们提出了一个联合的实验和计算研究的速度场和OH和CH 2 O的分布在一个试点，部分预混湍流DME/空气射流火焰与射流出口雷诺数，ReD，为29300。湍流DME/空气火焰类似于充分研究的部分预混的甲烷/空气射流火焰Sandia Flame D，具有相同的化学计量混合物分数，Mrst = 0.35，和整体射流出口速度，Vbulk= 45.9 m/s。测量包括粒子图像测速（PIV）和同时CH 2 O和OH激光诱导荧光（LIF）成像。使用大涡模拟结合条件矩封闭（LES-CMC）的130万个单元的中间尺寸网格进行模拟。总的来说，下游的平均值和RMS的速度，OH和CH 2 O的配置文件的演变很好地预测，最大的差异发生在CH 2 O在x/D= 20-25。采用两种不同化学反应机制的LES-CMC模拟（Kaiser等人，2000 [20]和Zhao等人，2008 [21]）显示峰值CH 2 O摩尔分数的差异约为2倍，而OH摩尔分数在两种机制之间具有良好的一致性。OH和CH 2 O的单次激发LIF测量显示了这些中间物种的空间分布之间的宽范围的间隔距离，其间隙为毫米量级。这些物种之间的重叠的不稳定性表明，甲醛的消耗率由OH在湍流DME/空气射流火焰可能是高度间歇性的显着偏离小火焰模型。
Turbulent dimethyl ether (DME) jet flames provide a canonical flame geometry for studying turbulence–flame interactions in oxygenated fuels and for developing predictive models of these interactions. The development of accurate models for DME/air flames would establish a foundation for studies of more complex oxygenated fuels. We present a joint experimental and computational investigation of the velocity field and OH and CH2O distributions in a piloted, partially-premixed turbulent DME/air jet flame with a jet exit Reynolds number,ReD, of 29,300. The turbulent DME/air flame is analogous to the well-studied, partially-premixed methane/air jet flame,Sandia Flame D, with identical stoichiometric mixture fraction,ξst= 0.35, and bulk jet exit velocity,Vbulk= 45.9 m/s. Measurements include particle image velocimetry (PIV) and simultaneous CH2O and OH laser-induced fluorescence (LIF) imaging. Simulations are performed using a large eddy simulation combined with conditional moment closure (LES-CMC) on an intermediate size grid of 1.3 million cells. Overall, the downstream evolution of the mean and RMS profiles of velocity, OH, and CH2O are well predicted, with the largest discrepancies occurring for CH2O atx/D= 20–25. LES-CMC simulations employing two different chemical reaction mechanisms (Kaiser et al., 2000 [20] and Zhao et al., 2008 [21]) show approximately a factor of two difference in the peak CH2O mole fractions, whereas OH mole fractions are in good agreement between the two mechanisms. The single-shot LIF measurements of OH and CH2O show a wide range of separation distances between the spatial distributions of these intermediate species with gaps on the order of millimeters. The intermittency in the overlap between these species indicates that the consumption rates of formaldehyde by OH in the turbulent DME/air jet flame may be highly intermittent with significant departures from flamelet models.