Role of large‐scale structure in a nonreacting turbulent CH4 jet
Role of large‐scale structure in a nonreacting turbulent CH4 jet
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大型结构在非反应湍流 CH4 射流中的作用
DOI：
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
J. Kelly
中科院分区：
文献类型：
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作者：
R. Schefer;A. Kerstein;M. Namazian;J. Kelly
利用湍流CH4射流中CH4浓度的平面成像研究了射流中有组织的大尺度结构的存在。测量结果表明，大规模的旋涡结构的发展，在混合区附近的中心射流。这些结构导致瞬时径向分布与以前使用单点测量测量的经典时间平均高斯分布有很大不同。的配置文件通常由一个或两个相对均匀的浓度的高原地区，并与其他调查人员在恒定密度和反应流获得的平面测量是一致的。结果表明，混合模型中，卷吸的主要机制是大规模的周围空气的旋涡结构的吞没，然后与射流快速混合。传统的时间平均统计（平均值、RMS波动和概率分布）可以用这种大尺度结构来解释。
The existence of organized large‐scale structure in jet flows has been studied using planar imaging of the CH4 concentration in a turbulent CH4 jet. The measurements show the development of large‐scale vortical structures in the mixing region adjacent to the central jet. These structures result in instantaneous radial profiles that differ considerably from the classical time‐averaged Gaussian profiles measured previously using single‐point measurements. The profiles typically consist of one or two plateau regions of relatively uniform concentration and are consistent with planar measurements obtained by other investigators in constant density and reacting flows. The results suggest a mixing model in which the dominant mechanism for entrainment is large‐scale engulfment of surrounding air by the vortical structures, followed by rapid mixing with jet fluid. Conventional time‐averaged statistics (mean, RMS fluctuations, and probability distributions) can be interpreted in terms of this large‐scale structure.