Flow-Induced Vibration and energy harvesting of three tandem-arranged hydrofoils

This article investigates a Flow-Induced Vibration (FIV) based ocean current energy harvesting method utilizing hydrofoils, proposing an efficient energy harvesting scheme that utilizes tandem hydrofoils to capture the wake energy from upstream flow. Numerical simulations of the FIV response and energy harvesting of three tandem NACA 0012 hydrofoils were performed using the two-dimensional unsteady Reynolds-Averaged Navier-Stokes (uRANS) equations with the SST k-ω turbulence model. The center-to-center spacing between hydrofoils ranged from 2.5D to 4D (where D is the chord length of the hydrofoil). The results indicate that as the flow velocity increases from 0.2 m/s to 2 m/s (5.3 × 10⁴<Re < 5.3 × 10⁵), the total harvested energy increases, reaching a peak value of 62.3W. The optimal energy harvesting spacing ratio varies with increasing flow velocity. The spacing that maximizes energy harvesting is 2.5D for 0.2 m/s to 0.8 m/s, 3D for 1 m/s, 3.5D for 1.2 m/s to 1.8 m/s, and 4D for 2 m/s. Under most conditions, both the amplitude response and energy harvesting performance of the middle and behind hydrofoils surpass those of the front hydrofoil. The converted power of the middle and behind hydrofoils can be as high as 24 times and 34 times that of the front hydrofoil.