On the evolution of turbulent boundary layers during flame-wall interaction investigated by highly resolved laser diagnostics
On the evolution of turbulent boundary layers during flame-wall interaction investigated by highly resolved laser diagnostics
复制标题
通过高分辨率激光诊断研究火焰-壁相互作用过程中湍流边界层的演变
DOI：
10.1016/j.combustflame.2023.113276
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发表时间：
2024
影响因子：
4.4
通讯作者：
Zentgraf F
中科院分区：
文献类型：
--
作者：
Zentgraf F
火焰-壁面相互作用（FWI）条件下的湍流边界层行为对气/固界面的质量和能量传递有重要影响。详细的实验解决湍流边界层的发展存在FWI缺乏，这阻碍了知识。这项工作提出了一种粒子图像测速（流场），双泵相干反斯托克斯拉曼光谱（气体温度），和OH激光诱导荧光（火焰拓扑）测量的组合，研究在FWI的存在下的边界层结构的演变。实验是在侧壁淬熄（SWQ）燃烧器中进行的。结果表明，反应边界层流动坚持线性标度律u+= y+在粘性子层，直到y+= 5。超过y+= 5时，火焰改变速度和温度场，使得u z+流向速度偏离粘性子层和原木层中的壁面标度定律，u z+小于非反应流的壁面标度定律（下标z指流向坐标，在本手稿中通篇使用）。随着流体接近壁处的火焰冲击位置，气体温度显著增加，导致运动粘度ν增加三倍。虽然近壁流向速度梯度d< U z>/dy| y= 0 mm减小，ν增大越大，uz+减小越大，导致偏离壁面定律。在火焰冲击位置的下游，ν相对恒定，u z+值开始接近壁面定律的值。SWQ和迎面淬火火焰拓扑结构的趋势，旨在帮助更准确的壁模型的发展。
The turbulent boundary layer behavior in the presence of flame–wall interactions (FWI) has an important role on the mass and energy transfer at the gas/solid interface. Detailed experiments resolving the turbulent boundary layer evolution in the presence of FWI are lacking, which impedes knowledge. This work presents a combination of particle image velocimetry (flow field), dual-pump coherent anti-Stokes Raman spectroscopy (gas temperature), and OH laser induced fluorescence (flame topology) measurements to study the evolution of the boundary layer structure in the presence of FWI. Experiments are conducted in a side-wall quenching (SWQ) burner. Findings reveal that the reacting boundary layer flow adheres to the linear scaling law u+= y+ in the viscous sublayer until y+= 5. Beyond y+= 5, the flame modifies the velocity and temperature field such that the u z+ streamwise velocity deviates from the viscous sublayer and the law-of-the-wall scaling in the log-layer with u z+ being smaller than that of the non-reacting flow (the subscript z refers to the streamwise coordinate and is used throughout this manuscript). As the fluid approaches the flame impingement location at the wall, the gas temperature increases significantly, causing a threefold increase in kinematic viscosity, ν. Although the near-wall streamwise velocity gradient d< U z>/d y| y= 0 mm decreases, the larger increase in ν reduces u z+ and leads to the deviation from the law-of-the-wall. Downstream the flame impingement location, ν is relatively constant and u z+ values begin to approach those of the law-of-the-wall. Trends are presented for SWQ and head-on quenching flame topologies, and are intended to help development of more accurate wall models.