Numerical Study on Vibration Attenuation of Cylinder using Active Rotary Oscillating Controller

Abstract

The present article is an attempt at utilizing a feedback control system based on cylinder rotary oscillations in order to attenuate the two-degree-of-freedom vibrations of an elastically-supported square-section cylinder in presence of flow. The control system benefits from the cylinder rotational oscillations about its axis that acts according to lift coefficient feedback signal of the cylinder. Based on the performed numerical simulations, it becomes clear that the active control system has successfully mitigated the two-degree-of-freedom vibrations of square cylinder both in the lock-in region and galloping zone. For a Reynolds number of Re = 90 located in the lock-in region, the active rotary oscillating (ARO) controller has achieved a 98% reduction in the cylinder transverse vibration amplitude, while the corresponding value for the in-line vibration is 88%. Moreover, for a Reynolds number of Re = 250 in the galloping zone, the ARO controller has successfully attenuated the cylinder transverse vibration amplitude by 72%, while the same value for the in-line vibration is 70%. One also observes that the ARO controller decreases the amplitude of lift and drag coefficients in the lock-in region by, respectively, 95% and 94%. In contrast, the corresponding percentages for the cylinder in the galloping zone are 24% and 39%, respectively.