This study demonstrates an experimental realization of turbulence control strategies previously explored by Choi et al. (J. Fluid Mech., vol. 262, 1994, pp. 75–110) through numerical simulations. To conduct the experiments, a deformable surface with a streamwise array of 16 independently controlled actuators was developed. A real-time particle image velocimetry (RT-PIV) system was also created for flow measurements. The objective of the control strategy was to target the sweep and ejection motions of the vortex shedding from a spherical cap placed in a laminar boundary layer. Reactive control strategies consisted of wall-normal surface deformations that opposed or complied with the wall-normal (v) or streamwise (u) velocity fluctuations obtained from the RT-PIV. The results showed two primary outcomes of the control approach. Firstly, it effectively hindered the advancement of sweep motions towards the wall. Secondly, it disrupted the periodic shedding of vortices. The v-control with opposing wall motions and u-control with compliant wall motions exhibited strong inhibition of sweep motions, while the v-control with compliant and u-control with opposing wall motions showed weaker inhibition. All reactive control cases resulted in the disruption of vortex shedding. In some instances, this disruption was accompanied by increased turbulent kinetic energy due to the generation of additional flow motions. However, the v-control with opposing wall motions significantly reduced the vortex-shedding energy while maintaining total turbulent kinetic energy close to or below that of the unforced flow. Overall, the experiments show the effectiveness of reactive control strategies in mitigating sweep motions and disrupting vortical structures, offering insights for developing reactive control strategies.

中文翻译：

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使用主动变形表面和实时 PIV 对速度波动进行反应控制

这项研究展示了 Choi 先前探索的湍流控制策略的实验实现等人。（J.流体机械。，卷。 262, 1994, 第 75-110 页）通过数值模拟。为了进行实验，开发了一个可变形表面，该表面具有 16 个独立控制致动器的流向阵列。还创建了用于流量测量的实时粒子图像测速（RT-PIV）系统。控制策略的目标是针对层流边界层中球冠脱落的涡旋扫掠和喷射运动。反应控制策略包括与壁法线相反或顺从的壁法线表面变形（v) 或流向 (你）从 RT-PIV 获得的速度波动。结果显示了控制方法的两个主要结果。首先，它有效地阻碍了向墙壁的扫掠运动的推进。其次，它扰乱了漩涡的周期性脱落。这v-通过相反的壁运动进行控制和你-顺应壁运动的控制表现出对扫掠运动的强烈抑制，而v- 合规控制你-具有相反壁运动的控制表现出较弱的抑制。所有反应控制情况均导致涡旋脱落的破坏。在某些情况下，这种破坏伴随着由于产生额外的流动运动而增加的湍流动能。但是，那v-反向壁运动的控制显着降低了涡旋脱落能量，同时保持总湍流动能接近或低于非受迫流的动能。总体而言，实验表明了反应控制策略在减轻扫掠运动和破坏涡流结构方面的有效性，为开发反应控制策略提供了见解。