The compressible turbulent shear layer: an experimental study
The compressible turbulent shear layer: an experimental study
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DOI：
10.1017/s0022112088003325
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发表时间：
1988-12
影响因子：
3.7
通讯作者：
D. Papamoschou;A. Roshko
中科院分区：
文献类型：
--
作者：
D. Papamoschou;A. Roshko
在一种新型装置上实验研究了可压缩平面剪切层的生长速率和湍流结构。在这个装置中，可以流动不同密度的相似或不同的气体，并为每个流选择不同的马赫数。研究了十种气体和马赫数的组合，其中自由流马赫数范围从0.2到4。曝光时间为20ns的纹影摄影显示出非常低的扩散速率和大规模的结构。湍流区域的增长是通过在几个流向位置测量的皮托压力剖面来定义的。定义了一个可关联和统一实验结果的压缩效应参数。它是在与主导波的速度和切变层的结构相对流的坐标系中的马赫数，这里称为对流马赫数。它恰好对每个流具有几乎相同的值。在目前的实验中，它的取值范围是0到1.9。在相同的速度和密度比下，增长率用不可压缩值归一化后，增长率与对流马赫数的相关关系近似地落在一条曲线上。在不可压缩流动中，归一化增长率是统一的，随着对流马赫数的增加，归一化增长率迅速减小，在超声速对流马赫数下趋近于0.2左右。
The growth rate and turbulent structure of the compressible, plane shear layer are investigated experimentally in a novel facility. In this facility, it is possible to flow similar or dissimilar gases of different densities and to select different Mach numbers for each stream. Ten combinations of gases and Mach numbers are studied in which the free-stream Mach numbers range from 0.2 to 4. Schlieren photography of 20-ns exposure time reveals very low spreading rates and large-scale structures. The growth of the turbulent region is defined by means of Pitot-pressure profiles measured at several streamwise locations. A compressibility-effect parameter is defined that correlates and unifies the experimental results. It is the Mach number in a coordinate system convecting with the velocity of the dominant waves and structures of the shear layer, called here the convective Mach number. It happens to have nearly the same value for each stream. In the current experiments, it ranges from 0 to 1.9. The correlations of the growth rate with convective Mach number fall approximately onto one curve when the growth rate is normalized by its incompressible value at the same velocity and density ratios. The normalized growth rate, which is unity for incompressible flow, decreases rapidly with increasing convective Mach number, reaching an asymptotic vaue of about 0.2 for supersonic convective Mach numbers.