Performance evaluation of a vortex induced piezoelectric energy converter (Vipec) with cfd approach

Abstract

A novel vortex induced piezoelectric energy converter (VIPEC) was present in this paper to harvest flow kinetic energy from the ambient environment through a piezoelectric beam. The converter consists of a circular cylinder, a pivoted beam attached to the tail of the cylinder and several piezoelectric patches. Vortex induced pressure difference acts on the beam and drives the beam to squeeze piezo patches to convert fluid dynamic energy into electric energy. Transition Shear Stress Transport (SST) combined with Scale Adaptive Simulation (SAS) model was employed to predict the turbulent flow and flow separation around the cylinder with various beam lengths at high Reynolds number of 8 × 104 based on the computational fluid dynamics (CFD) approach. The accuracy of SST-SAS model was investigated through verification and validation studies. The output voltage equation was derived from the piezoelectric constitutive equation. It was revealed that the beam length influences the flow wake pattern, the separation angle and shedding frequency greatly through changing the adverse pressure gradient around the cylinder. The wake pattern becomes symmetrical about the beam when the beam length is longer than a critical value. The length of the beam has little influence on the separation angle. When the beam length is about 1.3 times the diameter of the cylinder, the shedding frequency and output voltage achieves its maximum, and the separation angle is minimal. Maximal output voltage reaches 20 mV.