Airfoil-based electromagnetic wind energy harvester (Conference Presentation)

Vibration energy is one of the most common sources of energy that can be harvested from. Two vibration-to-energy conversion mechanisms are piezoelectric and electromagnetic [1,3]. The vibration of a cantilever beam is a popular method to harvest energy from piezoelectric and electromagnetics. When a cantilever beam vibrates from an external force the beam deflects back and forth. A piezoelectric material produces energy from the strain the beam is under. An electromagnetic array produces energy as a coil that is attached to the beam moves across the magnetic field of the array. More energy can be produced when a coil moves through a larger and more concentrated magnetic field. We propose a two degree of freedom aeroelastic energy harvester that uses a Halbach electromagnetic array and microfiber composite (MFC) piezoelectric patches, shown in Fig. 1. A Halbach array is a specific arrangement of magnets that focuses the magnetic field onto one side of the array while negating the field on the other side [2] whereas a normal alternating array has its magnetic field even distributed both sides of the array. The microfiber composite (MFC) patch is primarily for increasing the stiffness while negligibly increasing the mass of the cantilever beam. Wind tunnel test results are presented to characterize power output and the flutter speed of the energy harvester at different wind speeds. The harvester reaches the flutter speed at 3.5 m/s and operates up to 5 m/s and produces a power of 300 mW. The harvester is compact and fits inside an 8in square duct.