Investigation on the characteristics of a novel internal resonance galloping oscillator for concurrent aeroelastic and base vibratory energy harvesting

Abstract

Harnessing energy from concurrent wind flow and base vibration is a prospective method to enable self-powered sensing in the circumstances where wind and base motion are coexisting, like aircrafts, bridges, railways and ocean buoys. This paper proposes a novel two-degree-of-freedom galloping energy harvester with 2:1 internal resonance for efficient dual-source energy harvesting. The harvester consists of a primary and a secondary beam with a square-sectioned bluff body attached to the free end and two pairs of magnets repulsively arranged at the beam joint. Careful tuning of the magnetic force with a quadratic nonlinear stiffness term triggers the internal resonance, leading to a remarkably superior performance compared to its linear counterpart. A fully coupled aero-electro-mechanical distributed parameter model is established based on Euler-Bernoulli beam theory and quasi-steady aerodynamic hypothesis. Explicit analytical solution for steady-stage mechanical and electrical responses is derived using harmonic balance method and validated by numerical simulation. At the wind speed of 3 m/s and base acceleration of 0.9 m/s2, the conceptual prototype achieves a 211.1% increase in the effective bandwidth and a 50% increase in the peak voltage around the first resonance. The results provide a theoretical guideline to improve the system capacity of dual-source energy harvesting.