Hydrokinetic piezoelectric energy harvesting by wake induced vibration

Highlights: • A hydrokinetic energy harvester is proposed based on wake induced vibration. • Fluid-solid-electric coupling model is developed and validated by experimental data. • Reattach region is numerically and experimentally proved for high energy efficiency. • Wake induced harvesting power is 31 times of that without wake interference. Piezoelectric energy harvesters capture various kinetic energy to power wireless sensors. A new hydrokinetic piezoelectric energy harvester using wake-induced vibration (WIV) is proposed in this paper. The mathematical model of the hydrokinetic energy harvester is established to consider the effect for different velocity regions. Circulating water-channel experiment is carried out to exam the performance of the harvester. The experimental results show that the model can predict the output power appropriately. Frequency analysis indicates that the performances in VIV region and WIV region are dominated by the wake vortex frequency and the natural frequency respectively. The flow pattern changes greatly under different spacings which are divided into extended-body, reattachment and co-shedding regions. The maximum output power of the harvester locates in the reattachment region. The maximum experimental power densities for the inverted D-shaped, circular and D-shaped cylinders are 570.3W/m³, 596.4W/m³, 1074W/m³, respectively. They are 43.2, 25.3, 31 times of that without wake interference. The corresponding optimal experimental spacing ratios are 5, 2.6 and 2, respectively. Compared with the case without wake interference, the output power of the hydrokinetic piezoelectric energy harvester using WIV is significantly improved.