Design And Characteristic Analysis Of Curved Wind Energy Harvester Based On Gallop

As wireless sensor networks and low-power MEMS are widely used in various fields,the shortcomings of traditional energy supply methods are increasingly apparent.Self-powered technology that harvests energy from the environment and directly powers low-power electronic devices is an effective solution.Wind energy is a widely distributed and sustainable clean energy source.Different types of small wind energy harvesters have been designed,however,the existing wind harvesters generally have the disadvantages of complex structure,narrow effective working wind speed band,higher cut-in wind speed and lower output voltage and power density at low wind speed.Cantilever beam wind harvesters are widely used because of their simple structure,low frequency,easy miniaturization,and high compatibility.The performance of the wind energy collector is directly determined by the type and intensity of wind-induced vibration caused by the bluff body at the free end of a cantilever beam.Compared with the conventional cross-section(square,regular-triangle,and D-shaped)bluff bodies,the special-section bluff body has better aerodynamic performance and higher energy harvesting efficiency in the field of wind energy harvesting.To solve the shortcomings of the existing wind energy harvesters,a curved-plate bluff body is studied for enhancing the performance of piezoelectric wind energy harvester based on galloping phenomenon.The proposed curved-plate bluff body seems to have more design flexibility and the possibility of improving aerodynamic performance.Numerical simulations of the flow field show that the aerodynamic performance of the curved-plate bluff body(L = 45mm)and the efficiency of wind energy collection are better than those of other arc-length curved-plate bluff bodies and the traditional cross-sectional bluff bodies.The theoretical model of lumped parameters of curved wind wind harvester is established and verified by wind tunnel experiment.A curved wind energy harvester prototype was produced and wind tunnel tests were conducted,the effects of external load resistance and arc length on the electrical output characteristics were studied.The curved wind energy harvester(L =45mm)has the best output voltage and power,which is higher than that of the comparison group,and the curved wind energy harvester has the lowest cut-in wind speed.When an external load resistance of 820 K? is connected and the arc length is45 mm,the piezoelectric wind energy harvester with curved-plate bluff body under5.5 m/s wind speed generates an average power of 35.6 ?W.In order to further improve the performance of curved wind energy harvesters,the effects of additional wings and additional end caps on the aerodynamic performance and output voltage of curved wind energy harvesters were studied using flow field simulation and wind tunnel test methods.The simulation results show that both the additional wing and the additional cover can improve the aerodynamic performance of the curved-plate bluff body and obtain more transverse aerodynamic force.The wind tunnel test results show that the output voltage of the curved-plate wind energy harvester with arc length in the range of 45 mm ~ 65 mm is increased with the additional wing length.The additional cover increases the output voltage of the curved wind collector.The output voltage increment of the collector with the arc length L ? 55 mm is higher than that of the collector with the arc length L < 55 mm,and the voltage increment is the maximum when the arc length L = 60 mm.In addition,the additional wing and the additional cover reduce the cut-in wind speed of the curved wind energy harvester from 2 m/s to 1.5 m/s.