Optimization of Galloping Piezoelectric Energy Harvester with V-Shaped Groove in Low Wind Speed

Effects of Aerodynamic Parameters on Performance of Galloping Piezoelectric Energy Harvester Based on Cross-Sectional Shape Evolutionary Approach

This study explores the potential effects of the aerodynamic parameters on the performance of the galloping piezoelectric energy harvester. By considering the geometric configurations, a bluff body cross-sectional shape evolution approach is proposed using Boolean operations on the polygons and forty-eight different cross-sectional shapes with the protruding and depressed features are considered. Computational fluid dynamics is employed to perform a time-varying simulation of the aerodynamic characteristics. The effects of the aerodynamic parameters on performance are investigated computationally using a distributed parameter electromechanical coupling model. The critical wind speed, maximum output power, and the slope of the power versus wind speed curve are introduced as the performance evaluation parameters. The results show that the rear-side protruding feature and the top-side and bottom-side depressed feature have significant potential to enhance the performance. Furthermore, a symmetrical structure of the cross-sectional shape in the downstream direction should be prioritized over asymmetric designs.

Design Parameters Affecting the Performance of Vortex-Induced Vibration Harvesters

Vortex-induced vibration harvesters are usually equipped with small piezoelectric patches mounted near the cantilever clamp, where the largest longitudinal stress occurs. This paper, aiming to improve energy harvesting performance, investigates the possibilities of extending the patch length and modifying the length and mass of a bluff body mounted on a harvester to induce vortex shedding. A novel analytical model based on dimensionless numbers is presented to determine the output voltage generated by a cantilever harvester subjected to periodic vortex shedding. This model highlights the design parameters having the largest influence on harvester performance and provides guidance to the planning of experimental tests and the interpretation of experimental results. Some prototype harvesters with different designs are built. First, experimental tests are carried out to identify the natural frequencies and damping ratios of the prototypes; then, the prototypes are tested in a wind tunnel to assess energy harvesting performance. The best performance is achieved when the patch length is about 20% of the cantilever length, the bluff body is long, and its mass reaches the minimum value. This result agrees with the prediction of the model.

Wind energy harvester using piezoelectric materials

Wireless sensor networks play a very important role in environmental monitoring, structural health monitoring, smart city construction, smart grid, and ecological agriculture. The wireless sensor nodes powered by a battery have a limited service life and need periodic maintenance due to the limitation of battery capacity. Fortunately, the development of environmental energy harvesting technology provides an effective way to eliminate the needs and the replacement of the batteries. Among the environmental stray energy, wind energy is rich, almost endless, widely distributed, and clean. Due to the advantages of simple structure, miniaturization, and high power density, wind energy harvesters using piezoelectric materials (PWEHs) have attracted much attention. By the ways of principal exploration, structure design, and performance optimization, great and steady progress has been made in the research of PWEH. This Review is focused on the review of PWEHs. After introducing the basic principle of PWEHs, the structural performance and research status of PWEHs based on different mechanisms, such as a rotating turbine, vortex-induced vibration, flutter, and galloping, are analyzed and summarized. Finally, the development trend of PWEHs has been prospected.

Piezoelectric Energy Harvesting towards Self-Powered Internet of Things (IoT) Sensors in Smart Cities

Information and communication technologies (ICT) are major features of smart cities. Smart sensing devices will benefit from 5 G and the Internet of Things, which will enable them to communicate in a safe and timely manner. However, the need for sustainable power sources and self-powered active sensing devices will continue to be a major issue in this sector. Since their discovery, piezoelectric energy harvesters have demonstrated a significant ability to power wireless sensor nodes, and their application in a wide range of systems, including intelligent transportation, smart healthcare, human-machine interfaces, and security systems, has been systematically investigated. Piezoelectric energy-harvesting systems are promising candidates not only for sustainably powering wireless sensor nodes but also for the development of intelligent and active self-powered sensors with a wide range of applications. In this paper, the various applications of piezoelectric energy harvesters in powering Internet of Things sensors and devices in smart cities are discussed and reviewed.

Design and Experiments of a Galloping-Based Wind Energy Harvester Using Quadruple Halbach Arrays

This study aims to develop a device for harvesting electrical energy from low-speed natural wind. Four linear Halbach arrays are adopted to design a high-performance galloping harvester with the advantage of high durability and efficiency at low-frequency vibrations. The results of magnetic field analysis reveal that there are optimal sizes of the main and transit magnets of the Halbach arrays and coil to obtain the maximum magnetic flux density normal to the coil. The experimental and simulation results show that the electrical external load resistance significantly affects the vibration amplitude and the galloping onset velocity of the harvester. The results also reveal that the performance of the original design using the quadruple Halbach array was lower than that of the existing harvester because of the heavy magnet mass embedded in the tip prism. The modified design, reducing mass, improved the performance by four times compared to the original design.

A Piezoelectric and Electromagnetic Hybrid Galloping Energy Harvester with the Magnet Embedded in the Bluff Body

To meet the needs of low-power microelectronic devices for on-site self-supply energy, a galloping piezoelectric-electromagnetic energy harvester (GPEEH) is proposed. It consists of a galloping piezoelectric energy harvester (GPEH) and an electromagnetic energy harvester (EEH), which is installed inside the bluff body of the GPEH. The vibration at the end of the GPEH cantilever drives the magnet to vibrate, so that electromagnetic energy can be captured by cutting off the induced magnetic field lines. The coupling structure is a two-degree-of-freedom motion, which improves the output power of the energy harvester. Based on Hamilton's variational principle and quasi-static hypothesis, the piezoelectric-electromagnetic vibrated coupling equation is established, and the output characteristics of GPEEH are obtained by the method of numerical simulation. Using the method of numerical simulation, studies a series of parameters on the output performance. when the wind speed is 9 m/s, the effective output power of the GPEEH is compared with the classical galloping piezoelectric energy harvester (CGPEH) who is no magnet. It is found that the output power of GPEEH 121% higher than the output power of CGPEH. Finally, set up an experimental platform, and test and verify. The experimental analysis results show that the simulated output parameter curves are basically consistent with the experimental drawing curves. In addition, when the wind speed is 9 m/s, under the same parameters, the effective output power of the GPEEH is 112.5% higher than that of the CGPEH. The correctness of the model is verified.