Design and CFD simulations of a Vortex-Induced Piezoelectric Energy Converter (VIPEC) for underwater environment

A novel vortex-induced piezoelectric energy converter (VIPEC) is presented in this paper to harvest ocean kinetic energy in the underwater environment. The converter consists of a circular cylinder, a pivoted plate attached to the tail of the cylinder, several piezoelectric patches and a storage circuit. Vortex-induced pressure difference acts on the plate and drives the plate to squeeze piezo patches to convert fluid dynamic energy into electric energy. The output voltage is derived from the piezoelectric constitutive equation with fluid forces. In order to evaluate the performance of the VIPEC, two-dimensional computational fluid dynamics (CFD) simulations based on the Reynolds averaged Navier-Stokes (RANS) equation and the shear stress transport (SST) k-w turbulence model are conducted. The CFD method is firstly verified for different grid resolutions and time steps, and then validated using simulation and experimental data. The influences of the plate length and flow velocity on the wake structure, the driving force and the performance of the VIPEC are investigated. The results reveal that different parameters reach their peaks at different plate lengths, and the converter has a maximal output voltage of 2.3 mV in a specified condition and the maximal power density reaches 0.035 μW/m3 with a resistance load of 10 MW. The influence of the simulated subcritical Reynolds number on the driving force is not noticeable. The simulation results also demonstrate the feasibility of this device.