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首页> 外文期刊>Aerospace science and technology >On the coherent modes of high Reynolds number, strongly swirling jets discharging in compact enclosures. Part B: Coherent flow structure
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On the coherent modes of high Reynolds number, strongly swirling jets discharging in compact enclosures. Part B: Coherent flow structure

机译：在高雷诺数的相干模上，强旋流的射流在紧凑的外壳中排放。 B部分：相干流结构

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In this second part of a two article study, the coherent flow structure of a high Reynolds number, strongly swirling jet that includes in its core an energetic shear layer and that discharges in a square shaped cross-section duct is experimentally investigated. Selecting the jet diameter and average jet discharge velocity as characteristic scales, the swirl number, the duct cross section size, and the embedded shear layer circulation are all order one, whereas the flow Reynolds number is O(10(5)). The selected flow configuration and non-dimensional parameters are similar to those characterizing the flow in compact, lean premixed combustors presently being considered for aeroengine applications. Two space fixed, hot-wire probes are used as coherent mode detection and phase determination sensors to conduct detailed mode conditioned, LDV measurements. Spectral analysis of the hot-wire velocity signals shows the presence of three spatially and temporally coherent flow modes. The structure of the different modes is investigated using conditional post-processing specifically designed to analyze this high Reynolds number, complex flow field. The lowest frequency mode is seen to be linked to a precession instability of the swirling jet vortex breakdown region. The two other, more higher frequency modes are connected to the Kelvin-Helmholtz instability of the shear layer that develops in the swirling jet core. Symmetry arguments are used to partially reconstruct the vorticity structure linked to the shear layer instability modes. A close relation between the precession and the shear layer instability modes is found to occur. (C) 2015 Elsevier Masson SAS. All rights reserved.
机译：在两篇文章研究的第二部分中，实验研究了高雷诺数，强涡旋射流的相干流动结构，该射流的核心包括高能剪切层，并在方形截面的管道中排放。选择射流直径和平均射流排放速度作为特征尺度，旋流数，管道横截面尺寸和埋入的剪切层环流均为一阶，而流雷诺数为O（10（5））。所选的流量配置和无量纲参数与表征目前在航空发动机应用中所考虑的紧凑，稀薄的预混燃烧器中的流量的特征相似。两个空间固定的热线探头用作相干模式检测和相位确定传感器，以进行详细的模式调节的LDV测量。热线速度信号的频谱分析表明存在三种空间和时间相干的流动模式。使用专门设计用于分析这种高雷诺数，复杂流场的条件后处理来研究不同模式的结构。最低频率模式被认为与涡旋射流涡旋击穿区域的进动不稳定性有关。另外两个更高的频率模式与在旋流射流芯中形成的剪切层的开尔文-亥姆霍兹不稳定性有关。对称性参数用于部分重建与剪切层不稳定性模式相关的涡度结构。发现进动与剪切层失稳模式之间存在密切关系。 （C）2015 Elsevier Masson SAS。版权所有。

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