Characteristic features of large structures in compressible mixing layers
Characteristic features of large structures in compressible mixing layers
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DOI：
10.2514/3.13312
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发表时间：
1996-09
期刊：
影响因子：
2.5
通讯作者：
N. Messersmith;J. Dutton
中科院分区：
文献类型：
--
作者：
N. Messersmith;J. Dutton
利用平面激光Mie散射显示技术研究了可压缩混合层的大结构。收集了10例病例的大量数字图像，对应于3种不同压缩性条件、2种不同图像平面和2种接种方法的组合。三种流动条件分别为相对马赫数0.63、0.98和1.49。计算每个集合的二维空间协方差场，以表征混合层内观察到的典型大结构。横向视图的空间协方差表明，该结构被拉长，并向流线流动方向压缩，压缩性增加。倾斜图像的协方差有助于量化压缩性对结构的三维性质的影响，如通过随着压缩性的增加倾斜成像结构的尺寸增加和偏心率减少所证明的。
The large structures of compressible mixing layers have been investigated using planar laser Mie scattering visualizations from condensed ethanol droplets in the flow. Large ensembles of digital images were collected for 10 cases, corresponding to combinations of 3 distinct conditions of compressibility, 2 different image planes, and 2 seeding methods. The three flow conditions were at relative Mach numbers of 0.63, 0.98, and 1.49. The two-dimensional spatial covariance field was computed for each ensemble to characterize the typical large structure observed within the mixing layer. The spatial covariances of the transverse views indicate that the structures are elongated and compressed toward the streamline flow direction with increasing compressibility. Covariances of the oblique images help quantify the influence of compressibility on the three-dimensional nature of the structures, as evidenced by an increase in size and a reduction in eccentricity of the obliquely imaged structures with increasing compressibility.