Mixing and stabilization study of a partially premixed swirling flame using laser induced fluorescence
Mixing and stabilization study of a partially premixed swirling flame using laser induced fluorescence
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DOI：
10.1016/j.combustflame.2010.08.004
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发表时间：
2011
影响因子：
4.4
通讯作者：
D. Galley;S. Ducruix;F. Lacas;D. Veynante
中科院分区：
文献类型：
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作者：
D. Galley;S. Ducruix;F. Lacas;D. Veynante
为了表征旋流燃烧器的稳焰过程，利用平面激光诱导荧光（PLIF）对OH自由基和丙酮蒸气进行了实验研究，该实验与燃气轮机燃烧器有许多相似之处。这些诊断表明，稳定点在燃烧室中旋转，混合管末端的空气和燃料混合不完全。燃料质量分数沿混合管轴线呈指数衰减，横向分布呈高斯分布。然而，径向压力梯度倾向于将燃料困在混合管内轴向传播的涡流的核心。当混合管涡旋进入燃烧室时，涡旋击穿是通过进给涡芯（PVC）发生的。轴向传播的涡旋在燃烧室内呈螺旋轨迹，用横向丙酮PLIF观察到其轨迹。因此，燃烧室中火焰的稳定点随PVC结构旋转。在本研究中，用高速摄像机记录了火焰的自发发射，观察到了这一现象。稳定点旋转频率随质量流量的增加而增加。研究还表明，聚氯乙烯与阻燃剂之间的耦合是通过混合发生的，这解释了流动声波与反应速率之间的一种可能的耦合机制。这种方法也可以用于闪回，这个问题将在不久的将来得到更彻底的解决。
A laboratory-scale swirling burner, presenting many similarities with gas turbines combustors, has been studied experimentally using planar laser induced fluorescence (PLIF) on OH radical and acetone vapor in order to characterize the flame stabilization process. These diagnostics show that the stabilization point rotates in the combustion chamber and that air and fuel mixing is not complete at the end of the mixing tube. Fuel mass fraction decays exponentially along the mixing tube axis and transverse profiles show a gaussian shape. However, radial pressure gradients tend to trap the fuel in the core of the vortex that propagates axially in the mixing tube. As the mixing tube vortex enters the combustion chamber, vortex breakdown occurs through a precessing vortex core (PVC). The axially propagating vortex shows a helicoidal trajectory in the combustion chamber which trace is observed with transverse acetone PLIF. As a consequence, the stabilizing point of the flame in the combustion chamber rotates with the PVC structure. This phenomenon has been observed in the present study with a high speed camera recording spontaneous emission of the flame. The stabilization point rotation frequency tends to increase with mass flow rates. It was also shown that the coupling between the PVC and the flame stabilization occurs via mixing, explaining one possible coupling mechanism between acoustic waves in the flow and the reaction rate. This path may also be envisaged for flashback, an issue that will be more completely treated in a near future.