School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-744, Korea.
Philos Trans A Math Phys Eng Sci. 2011 Apr 13;369(1940):1540-55. doi: 10.1098/rsta.2010.0357.
In the present study, we apply proportional (P), proportional-integral (PI) and proportional-differential (PD) feedback controls to flow over a circular cylinder at Re=60 and 100 for suppression of vortex shedding in the wake. The transverse velocity at a centreline location in the wake is measured and used for the feedback control. The actuation (blowing/suction) is provided to the flow at the upper and lower slots on the cylinder surface near the separation point based on the P, PI or PD control. The sensing location is varied from 1d to 4d from the centre of the cylinder. Given each sensing location, the optimal proportional gain in the sense of minimizing the sensing velocity fluctuations is obtained for the P control. The addition of I and D controls to the P control certainly increases the control performance and broadens the effective sensing location. The P, PI and PD controls successfully reduce the velocity fluctuations at sensing locations and attenuate vortex shedding in the wake, resulting in reductions in the mean drag and lift fluctuations. Finally, P controls with phase shift are constructed from successful PI controls. These phase-shifted P controls also reduce the strength of vortex shedding, but their results are not as good as those from the corresponding PI controls.
在本研究中，我们将比例（P）、比例-积分（PI）和比例-微分（PD）反馈控制应用于 Re=60 和 100 时流过圆柱的流动，以抑制尾流中的涡旋脱落。在尾流中的中心线位置测量横向速度，并将其用于反馈控制。根据 P、PI 或 PD 控制，在靠近分离点的圆柱表面上的上部和下部狭槽处为流动提供致动（吹气/抽吸）。基于每个感测位置，对于 P 控制，获得了使感测速度波动最小的最佳比例增益。将 I 和 D 控制添加到 P 控制中，肯定会提高控制性能并扩大有效感测位置。P、PI 和 PD 控制成功地降低了感测位置处的速度波动，并减弱了尾流中的涡旋脱落，从而降低了平均阻力和升力波动。最后，从成功的 PI 控制中构建了具有相移的 P 控制。这些相移的 P 控制也降低了涡旋脱落的强度，但它们的结果不如相应的 PI 控制好。
