Energy harvesting from a rotational nonlinear energy sink in vortex-induced vibrations

Abstract

The concept of nonlinear energy sinks (NES) has been studied recently for passive fluid-induced vibration mitigation. A NES presents a fast and irreversible capacity of efficiently dissipating energy for various vibration problems. Besides, energy harvesting (EH) applications are suitable for generating electricity in vibrating mechanical structures. This work investigates the combination of a rotational NES with EH for the vortex-induced vibrations (VIV) of a cylinder exposed to airflow. The study considers an energy harvesting device comprising an electric generator ideally attached to the rotational NES mass pendulum shaft, resulting in a cylinder-NES-EH assembly. The model consists of an elastically mounted cylinder subjected to transverse airflow. The NES-EH is attached to the cylinder as a rigid pendulum arm with a mass at its tip that can freely oscillate, simultaneously absorbing the cylinder vibration and generating electricity. The fluid modeling is based on a wake model represented by the Van der Pol oscillator. The study is carried out by computational simulations of the differential equations of motion, and the rotational NES parameters optimization is done with the particle swarm method. Results comprise the analyses of the cylinder-NES-EH nonlinear dynamics characterization, identification of response regimes of the NES-EH system through a parametric study, and comparison with results from the literature. An optimal configuration was presented to maximize the generation of electric energy. Combining an EH with a rotational NES has shown an adequate potential for the design of energy extraction devices.