Research On Multi-Directional Wind Energy Harvester Based On FeGa/PZT Cylindrical Composite Beam

In recent years,wireless sensor networks(WSN)and micro-electromechanical systems(MEMS)have developed rapidly.There are many shortcomings in the use of traditional battery-powered methods to power wireless sensors and low-power electronic devices.It is an effective solution to realize the self-supply of electronic equipment through environmental energy harvesting and conversion technology.As a clean energy widely existing in nature,the collection and utilization of wind energy has become a current research hotspot.Due to the multi-directionality of environmental wind energy,the research of multi-directional wind energy harvesting has become one of the main development directions of wind energy harvesters.At present,most of the proposed wind energy harvesters use a thin rectangular beam structure,which can only effectively harvest wind energy in a specific direction,and have poor environmental adaptability.In order to realize the effective harvesting of wind energy in multiple directions,this thesis innovatively proposes a wind energy harvester based on FeGa/PZT cylindrical composite beam,and its performance is studied through simulation and experiment.In order to improve the performance of the harvester,the optimal design and experimental study of the bluff body are carried out.The main contents are as follows:(1)In order to realize the collection of multi-directional wind energy,the structure of the multi-directional wind energy harvester is designed.The FeGa thin cylindrical beam is selected as the cantilever beam,and the high-performance PZT ceramic tube PT120.0 is used as the transducer element.Due to the symmetrical characteristics of the cylindrical beam structure,it can vibrate in all directions along the two-dimensional section,thereby realizing the response and collection of multi-directional wind energy.(2)The theoretical analysis model of the wind energy harvester is established.The modal and output characteristics of the harvester are analyzed through multi-physics coupling simulation.Through the two-dimensional flow field simulation,the aerodynamic characteristics of the square prism bluff body under the action of wind in different directions are analyzed.The multidirectional performance of the harvester is preliminarily verified by the fluid-structure coupling simulation analysis.Experimental results show that the optimal resistance of the multi-directional wind energy harvester is 2.2MΩ.The output voltage of the square prism and cylinder bluff body harvesters increases with the wind speed.At a wind speed of 8m/s,the square prism bluff body harvester can obtain a maximum power of 0.495μW.Due to the advantages of the structure,the output of the cylinder bluff body harvester is more uniform in all directions,and the multi-directionality is better,while the output performance of the square prism bluff body harvester is better.The multi-directional performance of the wind energy harvester based on FeGa/PZT cylindrical composite beam is verified.(3)Combining the advantages of the square prism and the cylinder bluff body,a multitooth bluff body is proposed.Two-dimensional flow field simulation analysis shows that the 6-tooth and 8-tooth structures have larger lift amplitudes,and have better aerodynamic performance and multi-directionality.Experimental results show that in the entire wind speed range of 1.5～8m/s,6-tooth and 8-tooth bluff bodies have better capture performance than 10-tooth and 12-tooth bluff bodies.When the wind speed is 5～8m/s,the output voltage and power of the square prism bluff body are higher than 10-tooth and 12-tooth bluff bodies,but lower than 6-tooth and 8-tooth bluff bodies.(4)In order to improve the output performance of the wind energy harvester,an X-shaped bluff body is proposed.The two-dimensional flow field simulation analysis results show that the aerodynamic performance of the X-shaped bluff body with an angle of 90°～140° is better than that of the traditional square prism bluff body.Experimental results show that the output performance of the X-type bluff body with an angle of 90°～140° is better than that of the Xtype bluff body with an angle of 40°～80°.At a wind speed of 8m/s,the X-shaped bluff body with an angle of 140° can obtain an RMS voltage of 2.44 V and a power of 2.71μW.X-shaped bluff bodies with blade angles of 90°-90° and 80°-100° have more uniform output in all directions.Compared with the traditional square prism bluff body,the wind energy harvesting performance of the X-shaped bluff body shows great advantages at high wind speeds,and occupies a smaller space,which can effectively improve the output performance of the multidirectional wind energy harvester.