Two Coupled Piezoelectric Energy Harvesters With Cylinder From Induced Vortex

As a new methodology of energy harvesting, piezoelectric energy harvesting has attracted broad attention in recent years. Piezoelectric materials could be used to continuously harvest the vibrational energy from the oscillating environment, which exists extensively in the nature. Hence, the piezoelectric energy harvesting system, as a sustainable power source, can be a substitute for conventional chemical batteries, which have a limited life span. As a result, the cost can be reduced. In addition, flow induced vibration is a basic form of vibration which is always used to drive the piezoelectric energy harvester. The performance of the single piezoelectric energy h arvester has been studied in recent years. However, energy harvesters can be arranged in groups to save space and generate much more energy. The interactions between the harvesters might exert positive influences on their overall performances.In this paper, we investigate an energy harvester array with two identical piezoelectric energy harvesters submerged into water. According to the flow mechanics, elastic mechanics, mechanics of materials and piezoelectric etc., the mathematical model is established to analyze the vibration and performances of the two harvesters. The analytical expressions of the equivalent stiffness and equivalent mass are derived according to equivalence principle and then solved using MATLAB. The others equivalent parameters are obtained by experimental and numerical simulations.The flow forces imposed on the two energy harvesters are complicated to be computed, due to the coupling effects between them and lacking of relevant empirical formula. Therefore, simulations were conducted in FLUENT to simulate the flow flied, compute the flow forces, obtain the output powers, and update the positions of the two harvesters. The output powers were obtained by changing the arrangement form of the harvesters and modifying relevant parameters between them such as spacing ratio and water speed. Based on the results, the relations between the output power and the influential factors were analyzed. Finally, compared with the single harvester, the coupling of the two harvesters achieved better performances.Based on the results, an open-channel experiment platform and several energy harvesters were manufactured and assembled. Experiments were performed, with Lab VIEW DAQ programs for data processing, to verify the validation of the above mathematical model and the simulations results. The results are in good agreement, which indicates that the mathematical model and the simulations are resonable.