Relationship between upstream turbulent boundary-layer velocity fluctuations and separation shock unsteadiness
Relationship between upstream turbulent boundary-layer velocity fluctuations and separation shock unsteadiness
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DOI：
10.2514/2.1609
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发表时间：
2002
期刊：
影响因子：
2.5
通讯作者：
S. Beresh;N. Clemens;D. Dolling
中科院分区：
文献类型：
--
作者：
S. Beresh;N. Clemens;D. Dolling
用粒子图像测速技术和高频响应壁面压力测量研究了马赫数为5的非后掠压缩斜板干扰中上游湍流边界层特性和非定常分离激波特性之间的关系。正如在早先的工作中所提出的那样，在来流边界层厚度的变化和分离激波脚位置之间没有发现任何相关性。然而，以分离激波脚位置为条件的平均速度剖面，当激波在下游时比在上游时呈现出一种微妙的更丰满的形状。更重要的是，在上游边界层下三分之一的正向流方向速度波动和下游激波运动之间观察到明显的相关性，反之亦然。最强的相关性被发现的速度波动与频率约为4 - 10 kHz，这是显着低于频率的特点，在边界层中的大规模结构（40 kHz），虽然在换能器阵列的空间限制可能会限制仪器的灵敏度在这个较低的范围。这些结果在定性上与一个简单的物理原理是一致的，即一个较满的速度剖面使附面层的分离阻力增加，从而引起下游激波运动，而一个较不满的速度剖面则与较低的分离阻力有关，从而引起上游激波运动。
Particle image velocimetry and high-frequency response wall pressure measurements have been used to investigate the relationship between upstream turbulent boundary-layer properties and the unsteady separation shock behavior in a Mach 5 unswept compression ramp interaction. No correlation is found between variations in the incoming boundary-layer thickness and the separation shock foot position, as has been suggested in earlier work. However, themean velocity proe le, conditioned on theseparation shock foot position, exhibits a subtly fullershape when the shock is downstream than when it is upstream. More signie cantly, a clear correlation is observed between positivestreamwisevelocity e uctuations in thelowerthird of the upstream boundary layer and downstream shock motions, and vice versa. The strongest correlations are found for velocity e uctuations with frequencies of about4‐10 kHz, which is signie cantly lowerthan the frequencies that characterize the large-scale structures in the boundary layer (40 kHz), although spatial limitations in the transducer array may limit the instrument sensitivity to this lower range. These results are qualitatively consistent with the simple physical principle that a fuller velocity proe le imparts increased resistance to separation to the boundary layer and, hence, causes downstream shock motion, whereas a less-full velocity proe le is associated with lower resistance to separation and, hence, upstream shock motion.