Improving the galloping energy harvesting performance with magnetic coupling

Although wind energy is plenty in the realistic world, the low-speed wind energy usually can't be harvested efficiently. In this study, a novel galloping energy harvester is proposed based on two types of magnetic effect so as to improve the harvesting performance in the low-speed wind environment. The proposed energy harvester can evolve into three monostable versions according to the fixed magnets' number and location, i.e., the linear monostable galloping energy harvester (L-GEH), the wake monostable galloping energy harvester (WM-GEH) and the improved monostable galloping energy harvester (IM-GEH). A unified theoretical model covering the three versions is developed based on the extended Hamilton's theory. Corresponding numerical and experimental studies are conducted for comparative analysis. Compared to the results of the L-GEH and WM-GEH, the IM-GEH makes a great improvement in reducing the critical galloping wind speed and increasing the output power. The parameter analysis is conducted to describe the relationship between wind speed and galloping frequency. The computational fluid dynamics (CFD) analysis is carried out to reveal the underlying mechanism of performance enhancement. It is found that for the IM-GEH, the time required for boundary layer separation is decreased, thereby leading to the dense vortices and improving the efficiency of wind energy harvesting.