Fluid-Structure Instabilities in Flow Energy Harvesting Applications

Building fully autonomous and self-sustained electronic devices requires reliable in-situ power generation methods. A robust and promising approach is energy harvesting using fluid kinetic energy as its source. Among various proposed transduction mechanisms, we will focus on vibration-based piezoelectricity due to its robustness, high power density and electro-mechanical coupling efficacy. When coupled to fluid flow, exploiting fluid-structure instabilities to maintain self-sustained oscillations for consistent power output has shown to be an effective harvesting strategy. In this contribution, we will investigate the stability properties of an energy harvester design based on a piezoelectric beam, which is placed in a converging-diverging channel configuration. Using fully coupled three-dimensional direct numerical simulations of the fluid-structure interaction problem, we will deduce and validate a quasi one-dimensional model of the system based on leakage-flow type instability. This eventually allows us to identify the main mechanisms of fluid-induced vibration, which will be paramount for designing next-generation energy harvesters.