In-plane Omnidirectional Piezoelectric Wind Energy Harvester with the Elastic Support of a Spring

The wind-induced vibration energy harvester is an urgently needed power source for wireless sensor network nodes. In consideration that the wind direction in natural environments usually changes over time, it is of significance to develop wind energy harvesters which is insensitive to wind direction. This work presents an in-plane omnidirectional piezoelectric wind energy harvester (OPWEH) with the blunt body supported by a spring. The piezoelectric transducer is located inside the fully enclosed blunt body shell for protection. The wind makes the blunt body experience rotational vibration, and accordingly makes the piezoelectric transducer to generate electricity. To produce high electrical output, based on finite element simulations, the spring length is optimized to match the blunt body's rotational frequency and the piezoelectric transducer's bending frequency. Harvester prototypes were made and tested to investigate the performance of the proposed OPWEH. Experiments show that when the blunt body's rotational frequency is close to the piezoelectric transducer's bending frequency, the output power is the highest. the ratio of the measured minimum to maximum output power is about 0.81 when the wind direction changes in the horizontal plane. The prototype realizes the omnidirectional wind energy harvesting from the viewpoint of half power bandwidth.