Hybrid active flow induced vibration control of a circular cylinder equipped with a wake-mounted smart piezoelectric bimorph splitter plate

Abstract

A two-dimensional numerical study on active flow induced vibration (FIV) suppression of an elastically suspended circular cylinder fitted with a thin smart flexural-mode (bender-type) piezoelectric bimorph splitter plate on its wake side in real-time collaboration with a conventional base force actuator is carried out in laminar cross-flow condition (Re=100) for a wide range of reduced flow velocities (4≤U∗≤40). The numerical model is based on a strongly-coupled partitioned two-way iteratively implicit Fluid–Structure Interaction (FSI) routine implemented in a multiphysics simulation framework that interactively connects a CFD-based finite volume solver with a nonlinear transient computational structural dynamics (CSD) finite-element solver. A single-input-multi-output (SIMO) direct displacement feedback control law is introduced into the coupled transient dynamic simulation framework through an internal subroutine written in APDL command language. Three distinct feedback control configurations are implemented and compared, namely, the force-actuated, the piezo-actuated, and the hybrid actuation control systems, primarily aiming at suppression of cylinder transverse displacement amplitude. Further improvements on the controller performance are achieved by incorporating two modified hybrid actuation control strategies particularly designed for mitigation of excessive temporal oscillations of the drag and lift coefficients. Extensive numerical simulations reveal the important effects of splitter plate length, reduced velocity, and controller configuration on the key structural/flow-field parameters and flow structure. The hybrid actuation control configurations are found to provide a largely better displacement response control performance than the single-alone force-actuated or piezo-actuated systems. Also, the overall success of the modified hybrid control strategies in effective alleviation of the highly erratic lift and drag forces experienced by the smart cylinder-plate assembly is demonstrated. Lastly, it is concluded that if one primarily aims at prompt and forceful suppression of the base cylinder motion regardless of lift and drag force variations, the originally designed hybrid actuation control system is sufficiently adequate, while if one is specifically concerned with the severe temporal fluctuations in the lift and drag coefficients, the modified hybrid control configurations should be employed.