Optimizing a Vortex-Induced Energy Harvester: A 3D
Parametric Study of a Parallel Linkage-Airfoil Mechanism

Building upon a validated design for vortex-induced vibration (VIV) energy harvesting, this study conducts a comprehensive parametric analysis to optimize the system's performance. The primary objective is to identify the optimal geometric configuration of a parallel linkage-airfoil mechanism that maximizes energy extraction from low-velocity fluid flow. Utilizing a three-dimensional (3D) Fluid-Structure Interaction (FSI) model, this research systematically investigates the influence of two key parameters: the airfoil chord length and the longitudinal spacing between the cylinder and the airfoil. 3D numerical simulations were performed using an FSI model with the Spalart-Allmaras turbulence model. The simulations modeled a fluid domain with a uniform inflow velocity of 0.5 m/s. A cylinder with a diameter (D) of 60 mm was used as the upstream bluff body. The study evaluated four NACA0015 airfoils with chord lengths of 30, 45, 60, and 75 mm. For each airfoil, the longitudinal spacing was varied across five positions: 0.5D, 0.75D, 1.0D, 1.25D, and 1.5D. The system's effective stiffness was kept constant across all simulations to ensure a fair comparison of the power generation potential, which was directly correlated with the resulting transverse oscillation amplitude. The simulation results revealed a distinct optimal configuration. The NACA0015 airfoil with a 45 mm chord length, positioned at a spacing of 1.25D downstream from the cylinder, exhibited the maximum transverse oscillation amplitude. This specific configuration corresponds to the highest potential for power generation among all tested cases. These findings, derived from high-fidelity 3D simulations, provide critical design guidelines for the development of scaled-up, high-efficiency VIV energy harvesters and demonstrate the efficacy of simulation-driven design in optimizing complex three-dimensional systems.