Compressibility effects in the shear layer over a rectangular cavity
Compressibility effects in the shear layer over a rectangular cavity
复制标题
DOI：
10.1017/jfm.2016.540
复制
发表时间：
2016-06
影响因子：
3.7
通讯作者：
S. Beresh;J. Wagner;Katya M. Casper
中科院分区：
文献类型：
--
作者：
S. Beresh;J. Wagner;Katya M. Casper
本文利用流向中心平面上的粒子图像测速仪数据，研究了马赫数为0.6-2.5范围内，可压缩性对变宽度矩形空腔上方剪切层的影响。随着马赫数的增加，湍流强度的垂直分量在最宽的空腔中适度减小，但是两个较窄的空腔在所有三个分量以及湍流剪切应力中显示出更大的下降。这与典型的自由剪切层形成鲜明对比，典型的自由剪切层由于可压缩性而仅显示垂直分量和湍流剪应力的显着减少。空腔剪切层的涡度厚度在初始发展时迅速增长，然后在其不稳定性饱和时过渡到较慢的增长率。当用它们的估计不可压缩值进行标准化时，饱和前的增长率显示出随着对流马赫数的上升而抑制的经典压缩效应，与可比较的自由剪切层数据非常一致。由于可压缩性导致的生长速率降低的特定趋势由腔宽度修改。
The influence of compressibility on the shear layer over a rectangular cavity of variable width has been studied in a free stream Mach number range of 0.6–2.5 using particle image velocimetry data in the streamwise centre plane. As the Mach number increases, the vertical component of the turbulence intensity diminishes modestly in the widest cavity, but the two narrower cavities show a more substantial drop in all three components as well as the turbulent shear stress. This contrasts with canonical free shear layers, which show significant reductions in only the vertical component and the turbulent shear stress due to compressibility. The vorticity thickness of the cavity shear layer grows rapidly as it initially develops, then transitions to a slower growth rate once its instability saturates. When normalized by their estimated incompressible values, the growth rates prior to saturation display the classic compressibility effect of suppression as the convective Mach number rises, in excellent agreement with comparable free shear layer data. The specific trend of the reduction in growth rate due to compressibility is modified by the cavity width.