Mechanism And Experimental Research On Piezoelectric Generator Impacted By Jet-flow Based On Coanda Effect

Pneumatic driving technology is widely used in the field of industrial automation due to the advantages of large output thrust,simple structure,pollution-free.In order to ensure the continuous and reliable cooperative work of all functional components,many kinds of sensors are used to collect and monitor the real data of the pneumatic system because of the high integration of pneumatic system,complex working condition.Developing a novel continuous and effective energy supply technology for pneumatic system sensors has become a key technology problem to promote the development of pneumatic driving technology.In this paper,an air amplifier based on the Coanda effect is proposed,which is used to amplify the flow of compressed gas discharged from the pneumatic system.A more efficient cantilever piezoelectric generator excited by jet load is proposed to convert the energy of pneumatic system into electrical.Firstly,the effect of flow state on the Coanda effect is analyzed base on the theoretical model of the Coanda effect.Subsequently,the theoretical model of the energy conversion of the cantilever beam piezoelectric generator is established,and the energy harvesting mechanism of the cantilever beam piezoelectric generator is analyzed.The stress and strain states of the cantilever piezoelectric vibrator are studied theoretically under the impact load.Combining with the piezoelectric theory,the electrical output characteristics of the piezoelectric generator are analyzed.The FLUENT simulation analysis software was used to simulate and analyze the flow field distribution inside the air amplifier and at the jet port.The structure and dimensions of the air amplifier are determined.The COMSOL simulation analysis software is used to analysis the stress,strain and potential distribution of the piezoelectric vibrator surface when the piezoelectric vibrator is excited by impact load.The effect of the piezoelectric vibrator length and the magnitude of the load on the output voltage are studied.The analysis results show that the output open-circuit voltage increases with the increase of the length and load.In this paper,two kinds of jet impact piezoelectric generator with circular spoiler structure and airfoil spoiler structure are presented.In order to improve the energy conversion efficiency of the piezoelectric generator,a circular spoiler is added to the free end of the cantilever piezoelectric vibrator to increase the deformation of the cantilever piezoelectric.In addition,the influence of air flow parameters on the flutter state of the airfoil spoiler is studied by establishing a mathematical model of the pressure distribution on the upper and lower surfaces of the airfoil spoiler.An experimental test system for piezoelectric energy generator is established.The output characteristics of piezoelectric energy generator are systematically investigated.The experimental results show that the output open-circuit voltage increases with the increase of the gas flow rate,while declines with the increase of the gas pressure.Specifically,the maximum value of the output open-circuit voltage of the circular spoiler piezoelectric generator is 25.07 V,and the maximum instantaneous output power can reach 19.89 μW.The maximum value of the output open-circuit voltage of the airfoil-based spoiler piezoelectric generator is 23.33 V,and the maximum instantaneous output power can reach 13.06 μW.