Experimental Study of a Cantilever Piezoelectric Energy Harvester Utilising the Sloshing of a Liquid-Filled Container

To broaden the operating bandwidth of the vibration energy harvester at low frequencies, this paper presents a cantilever beam piezoelectric energy harvester (PEH) based on the sloshing of a liquid-filled container. The harvester is designed to recover energy from the multi-order sloshing modes of the liquid in the container. A mathematical model of the coupled system comprising the liquid within the container and the PEH was established. Based on the fluid–structure interaction (FSI) theory, the coupling mechanism between the liquid natural sloshing frequency and the immersed natural frequency of the beam was revealed. Experimental validation shows that the resonance characteristics of the PEH are mainly dominated by the liquid antisymmetric sloshing mode. Through comparative experiments, the effect of liquid-filled container and cantilever beam parameters on the PEH’s peak output voltage and operating bandwidth was systematically analysed. The performance of the PEH was significantly improved when the first-order natural frequency of the partially immersed beam approached the liquid natural sloshing frequency, with the bandwidth coefficient increasing by nearly fourfold under this condition. This research provides new ideas for the design and optimisation of piezoelectric energy harvesters in liquid sloshing environments.