Active management of naturally separated flow over a solid surface. Part 1. The forced reattachment process
Active management of naturally separated flow over a solid surface. Part 1. The forced reattachment process
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主动管理固体表面上自然分离的流动。
DOI：
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发表时间：
2004
影响因子：
3.7
通讯作者：
I. Wygnanski
中科院分区：
文献类型：
--
作者：
A. Darabi;I. Wygnanski
模拟一个简单的襟翼，实验研究了流体在倾斜平面上的强制再附着。从分离状态到附着状态的转变是由从襟翼肩部狭缝发出的周期性扰动的频率和振幅的突变引起的。激励参数决定了再附着过程的总持续时间。最优激励频率$F_{hbox{scriptsize{it opt}}}^{+}约为1.5$时，再附着时间最小，与振幅和皮瓣倾角无关。控制过程是通过增强流动中的大展向涡来实现的。连续涡旋的空间放大引起流体从襟翼表面的平均输运，导致主流重新附着。激发的时间尺度至少比典型的再附着时间小一个数量级。
The forced reattachment of flow to an inclined flat surface, simulating a simple flap, was investigated experimentally. The transition from a separated to an attached state of the flow was initiated by an abrupt change in the frequency and the amplitude of periodic perturbations emanating from a slot at the flap shoulder. The excitation parameters determined the total duration of the reattachment process. Minimum reattachment time occurred at an optimal excitation frequency of $F_{hbox{scriptsize{it opt}}}^{+} approx 1.5$, which was independent of amplitude and flap inclination. The control over the process was achieved by enhancing large spanwise vortices in the flow. Spatial amplification of consecutive vortices induces mean transport of fluid away from the flap surface which causes the main stream to reattach. The time scales of the excitation are at least an order of magnitude smaller than the typical reattachment times.