Experimental Study On Piezoelectric Energy Harvester Under Array Disturbance Excitation And Gradient Induced Hydraulic Jump

With the continuous development of information technology,the application of wireless sensors and small-size,low-power microelectronic devices involves medicine,food,military,aerospace,hydropower,agriculture and other aspects.Battery power supply can solve the power supply problem of most microelectronic equipment,but it is a little insufficient for the equipment with high cost of battery replacement.Piezoelectric energy harvester is a device that can convert the vibration energy in the environment into electrical energy to supply power for the equipment.The application of piezoelectric energy harvester to supply power for the microelectronic equipment can solve this problem well and can realize the self-supply of energy for the equipment under certain conditions.In order to improve the energy collection performance of cantilever piezoelectric energy harvester and broaden the application scope of flow induced vibration piezoelectric energy harvester,array disturbance test system and variable slope test system are designed.The influence of different array disturbance excitation on energy collection of different piezoelectric energy harvesters and different hydraulic jump caused by different flume inflow and different average velocity are studied experimentally,The energy collection of piezoelectric energy harvester with different mass at hydraulic jump is analyzed.The specific contents and conclusions include the following aspects:(1)Taking cantilever piezoelectric energy harvester as the research object,the self-circulating water channel is used to test the change of the collected power of piezoelectric energy harvester with the change of the external load resistance value under different flow rates.It is concluded that the output power of piezoelectric energy harvester first increases and then decreases with the increase of the external load resistance value,and the resistance value corresponding to the peak output power is about 3 ×105Ω.Through the analysis of the voltage time history curve and frequency spectrum obtained from the experiment,it is concluded that the vibration frequency of the semicircle cylinder piezoelectric energy harvester has little change with the increase of the external load resistance.With the increase of the flow rate,the vibration frequency shows a decreasing trend,and it is stable at 2.72Hz,2.64Hz and 2.57Hz when the flow rate is 0.35m/s,0.40m/s and 0.45m/s,respectively.(2)An array disturbance measurement system is designed to test the energy acquisition of piezoelectric energy harvesters with different mass and different arrangement of upstream,downstream and side array disturbance square arrays.The experimental results show that the upstream array disturbance column has the most obvious enhancement effect on the energy acquisition of semi cylindrical piezoelectric energy harvester,Compared with the complete arrangement of the disturbing column,the acquisition power is increased by 129.6 times;In order to verify the regulating effect of the upstream array around the column on the piezoelectric energy harvester,the energy acquisition of the piezoelectric energy harvester is further tested when the upstream array around the column is pulled out from the complete arrangement to the complete pull-out.The experimental test power first increases and then decreases,which verifies the previous test results;The results show that the upstream power is significantly greater than the downstream power,and the flow around square array has a good effect of current stabilization.(3)The slope changing test system is designed,and the slope changing angle is 1.125%in the fixed experiment.The acquisition power of the semi-circular cylinder piezoelectric energy harvester and the cylindrical piezoelectric energy harvester under different hydraulic jump caused by different flume inflow and different average velocity is tested and compared with the change of test position.The maximum acquisition power of the semi-circular cylinder piezoelectric energy harvester is 2.62mW,The maximum acquisition power of cylinder is 1.12mW;According to the experimental phenomena,the trend of the power curve of the piezoelectric energy harvester is corresponding to the three flow patterns observed in the experiment;From the experimental results,the power acquisition performance of the semicircle cylinder piezoelectric energy harvester is better than that of the cylinder piezoelectric energy harvester.The specific performance of the semicircle cylinder piezoelectric energy harvester is better than that of the cylinder piezoelectric energy harvester when the flow rate is large(80L/s,70L/s),and the cylinder piezoelectric energy harvester is better when the flow rate is small(60L/s).