Wind tunnel and initial field tests of a micro generator powered by fluid-induced flutter

Aeroelastic flutter is a self-oscillating phenomenon resulting from interaction between a structure and the surrounding flow. This is well-known as a destructive phenomenon. However, it can also be used as a powerful mechanism to harvest wind energy at the scales and costs beyond the reach of turbines. Windbelt is a micro generator exploiting wind energy with small size and capacity, which was invented and developed a few years ago (Humdinger wind energy LLC, 2007) basing on aeroelastic flutter. The aim of this paper is to investigate the influences of the design parameters on the performance of a windbelt with the goal of maximizing its output power. An experimental apparatus is developed to study the effects of parameters such as wind speed, position and size of the magnets, pre-applied tension of the membrane, angle of attack of the membrane, and the direction of the generator on the output power and frequency of the windbelt. The experimental tests are carried out in a subsonic wind tunnel. After that, we deduce optimal parameters from experimental results to maximize the output power. Two micro generators are then fabricated and tested in both wind tunnel and real condition. The results show that a single micro generator (windbelt) can generate a power of from 3 to 5 mW and a windpanel of 5 single windbelts (larger ones) can generate a power of from 30 to 100 mW at the wind speed of less than 8 m/s. This output is sufficient to power many micro devices such as wireless sensors, electronic chips, LEDs, and cell phone chargers. Therefore, this micro wind energy generator may be widely used in practice.