Closed-loop control for suppressing the vortex-induced vibration of a pipeline by the eigensystem realization algorithm

This study develops a feedback control strategy based on the eigensystem realization algorithm (ERA) reduced-order modeling to suppress vortex-induced vibration (VIV) in a spring-mounted pipeline. Initially, we linearize the full-order governing equations and employ a projection-free approach to construct the ERA reduced-order model (ROM) for pipeline flow. The ERA ROM is then integrated with the linear-quadratic-Gaussian algorithm to design an active flow control strategy utilizing blowing-suction actuators attached to the pipeline. Following validation of the reduced-order model's accuracy, we investigate the effects of damping ratio γ and various actuator configurations on VIV control. Our findings reveal that while damping ratio has minimal influence on the onset of VIV instability, it accelerates the suppression process without altering the fundamental control mechanism. Regarding actuator configurations, vertical jets demonstrate superior effectiveness in suppressing pipeline VIV compared to horizontal jets. The implementation of radial jets induces a novel low-frequency mode that achieves more rapid VIV suppression than unidirectional jets. Finally, dynamic mode decomposition (DMD) analysis is employed to examine the flow transition mechanism under control at γ=0. The dominant DMD modes exhibit consistent behavior, characterized by the attenuation of vortex shedding in the pipeline's wavemaker region.