Active feedback VIV control of sprung circular cylinder using TDE-iPID control strategy at moderate Reynolds numbers

The efficacy of active control of flow-induced vibrations in the turbulent flow around a sprung cylinder using time delay estimation based intelligent proportional-integral-derivative (TDE-iPID) controller is studied in this article. Two-dimensional incompressible unsteady Reynolds-averaged Navier-Stokes (URANS) equations are solved using the finite volume approach. The two-equation k-omega-SST model is employed for turbulence modeling, and fluid-structure interaction (FSI) simulations are conducted for a low mass damping ratio (m* zeta = 0.013) over the Reynolds number range of 1700-13000 which corresponds to the reduced velocities of 2-14.9. To validate the employed numerical procedure, the obtained findings for the cylinder cross-flow oscillations at different reduced velocities are compared with other empirical and numerical data, indicating a generally excellent agreement. In view of the numerical simulations, the utilized active control system can perfectly (up to almost 100%) attenuate the cross-flow and streamwise vibrations at the reduced velocity of 5 (Re approximate to 4200) that matches the maximum displacement in the lock-in region. Deploying the active controller disrupts the vortical structure especially in the far wake region, gradually transforming the vortex-shedding mode for the controller in the predefined green region from C(2S) to 2S where the vortices resemble the classical von Karman vortex street. Moreover, the controller performance is evaluated at the maximum vibration amplitude of the cylinder. The findings substantiate the success of an active control system in mitigating flow-induced vibrations immediately after switching the TDE-iPID controller on.