Piezoelectric Wind Energy Harvester Research Articles

Design and characteristic analysis of a high-performance deformable piezoelectric wind energy harvester based on coupled vibrations

The current vortex-induced vibration piezoelectric wind energy harvesters have a narrow operating wind speed range, while galloping piezoelectric energy harvesters are at risk of damage from excessive amplitude at high wind speeds, a novel high-performance deformable piezoelectric wind energy harvester based on coupled vibrations (DPWEH) has been proposed. The alteration of the compound blunt body shape effectively modifies the shedding characteristics and intensity of vortices, subsequently influencing the vibration mode and output voltage of the system. The vibration mode transitions from galloping to coupled vibration, ultimately to vortex-induced vibration. The rigid wing and long elastic beam suppress galloping at high wind speeds. A thinner flexible wing can extend the duration of coupled vibration. A smaller wing width ratio and larger Y-type base wing width are beneficial for increasing the output voltage. By optimizing the parameters of the compound blunt body, the onset wind speed can be effectively reduced, the effective wind speed bandwidth can be expanded, and the DPWEH can undergo coupled vibration for an extended duration while stably generating electricity. The peak output power is 0.36 mW at a load of 150 kΩ. Moreover, the energy harvester demonstrates the prolonged power generation capability of signal transmitters and 100 LED lights.

A centrifugal spring mechanism empowers self-adjusting in piezoelectric wind energy harvesting

Piezoelectric wind energy harvesters (PWEHs) offer promises in sustainable green energy supply for micropower electronics. However, traditional PWEHs encounter challenges in terms of high start-up wind speeds, subpar output performance, and narrow bandwidth, hampering their widespread adoption. To enhance the energy capture efficiency, a novel self-adjusting PWEH integrating a centrifugal spring mechanism (CSM) is presented. The CSM consists of a sliding rod, a 304 stainless steel spring, an exciting magnet, and a mass block. Additionally, the PWEH employs a vertical-axis blade design, allowing it to capture wind from different directions. Via theoretical analyses, finite element simulations, and experiments, key parameters of the PWEH are optimized including the CSM additional mass, spring wire diameter, and the configuration of multi-frequency piezoelectric transducers. Results demonstrate that the optimized PWEH works at 1.5m/s and generates 0.45mW, 2.742mW, and 5.973mW at wind speeds of 2m/s, 3.3m/s, and 4.75m/s, respectively. Compared to the unoptimized PWEH, the introduction of the CSM results in an 80.7% enhancement in open-circuit voltage and a 90.9% increase in short-circuit current. Additionally, by utilizing four pairs of piezo-transducers with different resonance frequencies (6.83Hz, 9.38Hz, 12.1Hz, and 14.8Hz), the resonance bandwidth of the PWEH is expanded to 1.5~5.5m/s. The feasibility of PWEH for powering signage, electronic screens, and Bluetooth thermohygrometer is demonstrated. The potential of PWEH in constructing high-precision intelligent wind speed monitoring systems is tested via convolutional neural networks. The study offers a strategy for designing the PWEH for both powering of the microelectronic devices, and intelligent sensing and monitoring of wind.

A piezoelectric oscillator for low-speed wind energy collection

ABSTRACT The exploration of low-speed wind harvesters is key to harnessing wind energy and enabling self-powered Internet of Things (IoT) sensor networks. In this paper, a piezoelectric oscillator (APO) for low-speed wind energy collection (B-WEC) is proposed and applied to low-speed wind energy harvesting. The magnetic model and power generation characteristics of the harvester are formulated, the magnetic torque is simulated, and the performance under different parameter combinations is tested experimentally. The results show that the APO rotation reduces the magnetic resistive torque by 26.00%. The highest peak-to-peak voltage is 92.35 V for an APO magnet diameter is 8 mm and the angle of the stopper (γ) is 60°, which is 1258.09% higher than fixed (γ is non-existent). Moreover, it has a maximum power of 0.56 mW at 4 m/s, and the optimally matched resistance is 200 kΩ. The harvester can light up about 150 LEDs. The B-WEC designed in this paper can effectively reduce the driving wind speed of piezoelectric wind energy harvesters and can be used as a power source for self-powered networked sensor networks. This study provides a new solution idea for the exploitation of wind energy.

Parameter effects on performance of piezoelectric wind energy harvesters based on the interaction between vortex-induced vibration and galloping

Our previous research experimentally validated that the interaction between vortex-induced vibration and galloping is an effective method for enhancing the performance of piezoelectric wind energy harvesters under low wind speed conditions. We proposed a distributed-parameter electromechanical coupling model as well. This study aims to investigate the effects of various parameters and optimize the performance of VIV-galloping interactive piezoelectric wind energy harvesters. Initially, we assessed the applicability of the model under different circuit and aerodynamic force conditions and discussed boundary and convergence conditions by replicating previous results. Further, simulations were performed to analyze the effects of the structural parameters of the bluff body and piezoelectric beam. The width or depth of the bluff body significantly influenced the low critical wind speed, interactive occurrence, and electrical output. To achieve a balance between material cost and electrical benefit, we recommend positioning the electrode length from the fixed end with a coverage ratio of at least 60%. Additionally, the output power is highly sensitive to the piezoelectric beam length, but reducing it results in a higher natural frequency and critical wind speed. We fabricated and tested four prototypes, which have demonstrated significantly higher power densities compared with previously reported values at the same wind speed.

Magnetic transfer piezoelectric wind energy harvester with dual vibration mode conversion

Wind-induced vibration piezoelectric energy harvesters have garnered significant interest in recent years as a means to power autonomous wireless sensor systems. A magnetic transfer piezoelectric wind energy harvester (MT-PWEH) is proposed and its durability, power generation performance and environmental adaptability are improved utilizing dual mode conversion. This MT-PWEH incorporated a downstream rectangular baffle, which facilitated the transition of the hollow cylinder from a traditional single vortex-induced vibration to a coupled vibration involving both vortex-induced vibration and galloping (i.e., the first vibration mode conversion). Besides, the vibration direction of the hollow cylinder was perpendicular to the vibration direction of the transducer, which achieved the purpose of limiting the amplitude (i.e., the second vibration mode conversion). The feasibility of MT-PWEH was confirmed through theoretical analysis, CFD simulation, fabrication and experiments. The experimental results demonstrated that the working characteristics of MT-PWEH were significantly affected by position and size of the baffle. Specifically, the ratio of the maximum cut-in wind speed of 12.5 m/s to the minimum cut-in wind speed of 1.2 m/s reached 10.4. Additionally, a maximum power output of 0.78 mW was recorded at 10 m/s with an optimal load resistance of 800 kΩ and 10 LEDs were drove successfully.

Design and Characteristic Analysis of a Performance-Enhanced Piezoelectric Wind Energy Harvester With a Transformable Y-Type Bluff Body

Design and Characteristic Analysis of a Performance-Enhanced Piezoelectric Wind Energy Harvester With a Transformable Y-Type Bluff Body

Exploring the influence of concave-convex surface modifications on piezoelectric wind energy harvesting: A numerical analysis

Wireless health monitoring sensors are significant for the safety of sea-crossing bridges, and their operation is dependent on a durable and reliable power source. Piezoelectric wind energy harvesters (PWEHs) can be effectively utilized in windy marine environments and provide a sustainable power supply for these sensors. This paper examines the influence of concave-convex surface modifications of a circular cylinder on the performance of the PWEH through numerical research to improve the output and operational bandwidth of traditional harvesters using cylindrical bluff bodies. An electromechanical model, coupled with computational fluid dynamics on low-Reynolds-number flows, was developed and different concave-convex configurations were proposed to explore the impact by numerical experiments. The results show that the configuration with two protrusions plus one groove is the optimal design. This configuration exhibits a much higher output with a maximum voltage of 19.5 V, representing a 464% increase compared to the cylindrical bluff body's 4.2 V, and a broader bandwidth with no upper limit across the wind speed range. This study provides insight into effective and ineffective efforts to enhance energy harvesting through concave-convex surface modifications and is advantageous to the advancement of self-powered marine sensing systems, particularly in the health monitoring of sea-crossing bridges.

Smart interference galloping energy harvester with optimally tunable gap between the bluff body and interference

This study focuses on the development of a piezoelectric wind energy harvester that utilizes the wake interference galloping phenomenon. We found that depending on the applied wind velocity, there exists an optimal gap distance between the oscillating bluff body and the interference, which produces the required wake interference galloping. Accordingly, we aimed to design a novel interference galloping–based energy harvester that can smartly adjust the bluff body location to its optimal position in response to the external wind velocity. The optimal gap distance between the two bodies for the wind velocity range considered in this study was found to be 9–15 mm, which strongly depends on the applied wind velocity. It was also observed that the phase delay of the lift force with respect to the displacement of the oscillating body plays a major role in determining the state of the system stability and that the wake interference galloping can also occur due to the memory effect. The phase angle of π/2 rad was found to be an important indicator for determining whether wake interference galloping occurs. The balance of forces on the bluff body is vital for determining the optimal location of the bluff body. The mathematical modeling was performed using the extended Hamilton principle, the Galerkin method, eigen- and multi-modal analyses, the extended Fourier theorem, and novel energy/power balance conditions that yielded the four additional equations required to compute the aerodynamic lift in an autonomous form. To identify the physical parameters for analyzing the proposed energy harvester system, a main experiment and several preliminary experiments were conducted. The analytical results were compared with the experimental data in terms of both the dynamic behavior and energy production, and they were observed to be sufficiently close (the maximum error in the averaged output power was 9.8%). The average output power from the proposed energy harvester was also compared with that from conventional interference galloping–based energy harvesters having an immobile bluff body; the results showed that the proposed energy harvester outperformed the conventional harvesters by up to 128.8%. Specifically, it generated an average output voltage of 71 V (rms) and an output power of 6.88 mW at a wind velocity of 10 m/s.

Study of a vortex-induced vibration piezoelectric wind energy harvester based on the synergy of multi-degree-of-freedom technology and magnetic nonlinear technology

A novel multi-degree-of-freedom and magnetic piezoelectric wind energy harvester (MNPWEH) is proposed in this work to improve the working bandwidth and output power for the wind energy harvesting based on vortex-induced vibration. In the process of studying the presented collaborative strategy utilizing multi-degree-of-freedom and nonlinear force enhancement technologies, four response states of the harvester are observed and named as inter-well state, intra-well state, pulse state, and intermittent state. The key factors determining these four response states are firstly obtained through a series of numerical simulations and pre-experiments. Then, a thorough investigation into the influence of structural parameters on these four response states and the output performance of the system has been conducted. The findings from the experimental results indicate that greater tip mass of the outer beams results in higher output voltage generated by the same state, while the excitation magnet spacing can be adjusted for meeting different requirements in power and working bandwidth. In the optimal configurations, the fabricated prototype finally can obtain a maximum average power of 1.83 mW under the condition of v = 5 m/s and s1 = 15 mm, and maintain a wide working bandwidth of 2 m/s −6 m/s with an average output power above 0.66 mW when s1 = 25 mm, respectively. The main contribution of this study has been to confirm the effectiveness of the collaborative use of the multi-degree-of-freedom technology and magnetic nonlinear technology in piezoelectric wind energy collection based on vortex-induced vibration. It also provides a deeper new insight into the performance improvement method for vortex-induced vibration piezoelectric wind energy harvester.

Harnessing multi-stable piezoelectric systems for enhanced wind energy harvesting

With the ongoing evolution of microelectronic devices toward lower power consumption, the utilization of piezoelectric materials for energy harvesting from wind-induced vibrations has garnered considerable attention. This study employs a combined approach involving finite element analysis and experiments to investigate the energy harvesting efficiency of the multi-stable piezoelectric wind energy harvester (MPWEH) and compares its performance with two alternative systems. The MPWEH demonstrates higher strains in both the x and y directions during reciprocating cross-well vibrations, establishing its superior energy harvesting efficiency compared to the alternative systems. Notably, at a wind speed of 8 m s−1, the MPWEH generates an output power nearly six times higher than local bistable piezoelectric energy harvester (LBPEH). The MPWEH achieves the maximum power density of 9.8125 mW cm−3, whereas the LBPEH registers the power density of 1.625 mW cm−3. The experimental results indicate that, under the optimal load resistance of 40 kΩ and a wind speed of 14 m s−1, the MPWEH achieves a peak output power of 2.76 mW, with a power density of 17.25 mW cm−3. The versatile applicability of the MPWEH extends across various low-power consumption microelectronic devices, positioning it as a valuable candidate for empowering continuous monitoring sensors in diverse domains.

Flutter-Driven Piezoelectric Wind Energy Harvesting System Based on PVDF Nanofiber for Low Power Applications

Flutter-Driven Piezoelectric Wind Energy Harvesting System Based on PVDF Nanofiber for Low Power Applications

Low-Wind-Speed Galloping Wind Energy Harvester Based on a W-Shaped Bluff Body

Galloping-based piezoelectric energy harvesting systems are being used to supply renewable electricity for low-power wireless sensor network nodes. In this paper, a W-shaped bluff body is proposed as the core component of a piezoelectric wind energy harvester. Experiments and simulations have shown that the W-shaped bluff body can improve harvesting efficiency at low wind speeds. For the W-shaped structure, the finite element simulation results indicate that the structure can help improve the aerodynamic performance to obtain high aerodynamic force. The experimental results demonstrate that compared with the traditional bluff bodies, the piezoelectric wind energy harvester with the W-shaped bluff body (WEHW) can generate higher output voltages and has a lower cut-in speed. When the length L is 30 mm and the rear groove angle β is 30°, the W-shaped structure can induce the best harvesting performance. When an external load resistance of 820 KΩ is connected and the wind speed is 5 m/s, the WEHW generates an average output power of 0.28 mW.

Structural optimization of laminated leaf-like piezoelectric wind energy harvesters based on topological method

In this paper, a series of leaf-like piezoelectric elements are proposed by using laminated structure of polypropylene (PP) and Polyvinylidene fluoride (PVDF) film to collect wind energy through vortex induced vibration. Topology optimization based on solid isotropic material with penalization method is employed in seeking optimal configurations of the elements. The PP and PVDF layer were set as optimization variables respectively to obtain topological layouts that would be equivalent to maximizes the overall strain energy as the objective function. Four simple shapes of piezoelectric elements with different topological configurations are manufactured and tested in wind tunnel to estimate the energy harvesting capabilities. The experimental results show that the reinforcement optimized long trapezoid model has the highest open-circuit output voltage of 4.01 V and output power of 6.125 μW at the wind speed of 12 m/s. For the optimization of piezoelectric materials, the short trapezoid model can reach the open circuit output voltage of 2.061 V and output power of 1.158 μW. It indicated that the topology optimization can indeed improve the energy harvesting efficiency of the piezoelectric element. However, this method is not universal at present, which means that the external shape of the model will influence the performance of the relevant optimization results.

Enhancing energy harvesting from flow-induced vibration of a semicircular wall via various upstream bluff bodies

Coupling vortex-induced vibration (VIV) and galloping is a promising strategy to enhance the performance of VIV-based piezoelectric wind energy harvesters (PWEHs). In this paper, we proposed to employ upstream bluff bodies to induce the wake of a downstream semicircular wall to evolve from VIV to galloping, where a PWEH was mounted to the semicircular wall. The effects of wind speed, spacing ratio, and cross-section of upstream bluff body on the output performance of the PWEH were examined experimentally. The results showed that an appropriate spacing ratio was required to ensure the occurrence of the wake evolution. Qualitative analyses revealed that the Strouhal number of upstream bluff body could tune the evolving behaviors of the semicircular wall, and the separation distance between VIV and galloping decreased with Strouhal numbers except for the cases in the near wake. The upstream circular and square cylinders performed better in driving the evolution than the trapezoidal and triangular cylinders. The maximum energy conversion efficiency improvement of 38.4% was achieved at a wind speed of 4.0 m/s with a spacing ratio of 10.0 for the upstream square cylinder, compared to that without an upstream bluff body. The findings provide beneficial guidance for developing efficient VIV and galloping coupled energy harvesters.

Investigation upon Piezoelectric Wind Energy Harvesters with Tandem Blunt Bodies of Different Geometries

Investigation upon Piezoelectric Wind Energy Harvesters with Tandem Blunt Bodies of Different Geometries

Piezoelectric wind energy harvester of bi-stable hybrid symmetric laminates

In this work, a bistable piezoelectric wind energy harvester (BPEH) is proposed, which is primarily made of bistable hybrid symmetric laminate (BHSL) and PZT, manufactured through a curing process. The air-solid-electric coupled finite element analysis model is established to simulate the dynamic response behavior of the BPEH and investigate the effects of varying airflow velocities on the flow field characteristics and performance output. A series of experimental studies on BPEH were conducted in the wind speed range of 8.5 m/s-16.5 m/s. The results show that at a wind speed of 14.5 m/s, the BPEH has an optimum external load of 60 kΩ, a maximum power output of 7.21 mW and a maximum amplitude of 93.065 mm. Therefore, the simple structure of the harvester proposed in this work may open a new way for bistable composite structures to acquire wind energy widely in natural environments.

An in-plane omnidirectional flutter piezoelectric wind energy harvester

Most wind energy harvesters that are based on wind-induced vibrations can only operate in a specific wind direction, which limits their application in environments with time-varying wind directions. Previously reported in-plane omnidirectional piezoelectric wind energy harvesters (PWEHs) based on vortex-induced vibrations can produce stable electrical output characteristics when the wind direction changes, but their output powers are relatively low and the working wind speed ranges are relatively narrow. To solve this issue, this work presents an in-plane omnidirectional flutter PWEH which is mainly composed of the bluff body of a hollow cylindrical shell and the inside elastic supporting structure of several piezoelectric composite beams. Finite element analysis shows that harvesters with both four and six supporting beams offer good stiffness and electromechanical conversion isotropies. Experiments demonstrate that both prototype devices are flutter PWEHs with rotation axes located on the rear of the geometrical center of the bluff body. The effect of wind speed on their directionality is small, and both prototypes show in-plane omnidirectional operation over a wide wind speed range, over which the electrical outputs remain relatively high. The prototype with six beams is preferred from the viewpoint of the wind direction adaptability. The onset wind speeds in different directions all range between 5.8 and 6.0 m/s, showing the good isotropy. The minimum and maximum powers are approximately 266.4 and 300.1 μW, respectively, at 10 m/s, and it shows in-plane omnidirectional energy harvesting performance in the wind speed range from 6.5 m/s up to more than 10 m/s.

Geometric modifications to bluff body for enhanced performance in a wind-induced vibration energy harvester

Specialized sensors in wireless networks monitor the environment with minimal power, which is typically provided by batteries but it can also be powered with renewable sources using smart materials. One such solution is piezoelectric wind energy harvesting to power these sensors. However, the low output power of piezoelectric materials is still a concern. This research aims to improve piezoelectric wind energy harvesting by modifying the geometry of the bluff body. A square-shaped bluff body is used as a reference, and geometric changes are made by attaching square-shaped extensions. The study creates a mathematical model of a cantilever beam system with a piezoelectric material at fix end and a bluff body at the free end, using a multi-physics approach that combines electromechanical and aerodynamic models. The study uses MATLAB Simulink to solve the differential equations and verify the results with experiments. A parametric analysis examines the impact of external resistance, wind speed, and bluff body shape on circuit metrics. The study found that at a wind speed of 6 m/s and an optimal load resistance of 200 kΩ, the system generated 4.984 mW of power. This result demonstrates the potential of wind energy harvesting to power various distributed sensors for a wide range of applications.

Performance enhancement of the wavy cylinder-based piezoelectric wind energy harvester with different wave-shaped attachments

The vortex-induced vibration (VIV)-based piezoelectric wind energy harvester (PWEH) has a small working bandwidth and poor wind energy harvesting performance. In order to improve the output power of the PWEH and achieve sustainable power supply for microelectronic products, this study proposes a novel wavy cylinder-based PWEH with two wavy attachment rods attached to the surface of the wavy cylinder, the mathematical model of PWEH is developed. The flow-induced vibration (FIV) response mechanism and the energy harvesting characteristics of the wavy cylinder-based PWEH are numerically explored. The wavy cylinder with wavy-shaped attachments produces a three-dimensional shear layer that can increase the wavy cylinder’s aeroelastic instability range and realize the synergistic effects of VIV and galloping, which increases the wave cylinder’s vibrational amplitude and lowers the galloping critical wind speed. Compared with the typical VIV-PWEH, the novel wind energy harvester can work outside the VIV lock-in range, and its output power and voltage rise as wind speed does. The wavy attachment rods with triangular cross section have greater advantages than other rods, its output power is 6.13 mW at a wind speed of 5.7 m/s and load resistance of 100 KΩ, compared with the circular cylinder PWEH, the average power increases by approximately 166%. The study’s findings can theoretically promote the enhancement of PWEH’s energy harvesting efficiency.

Multidirectional galloping-based wind energy harvester based on a cylindrical cantilever beam and multi-tooth blunt body

To improve the response-ability of the energy harvester to multi-directional wind, this paper proposes a galloping-based wind energy harvester by fixing a multi-tooth blunt body at the free end of a cylindrical cantilever beam, which consists of a long-straight FeGa thin cylinder and a piezoelectric tube. Combining the structural symmetry advantages of the multi-tooth blunt body and piezoelectric cylinder cantilever, the harvester can respond well to the wind from all directions of the two-dimensional plane. In the simulation and experiment, detailed comparative studies are carried out on the harvesters with square (four-tooth), six-tooth, eight-tooth, ten-tooth, and twelve-tooth blunt bodies. Within the wind speed range of 1.5 ∼ 8 m s−1, the results show that the harvester with a six-tooth blunt body has the best multidirectional wind response performance. When the wind speed is 8 m s−1, the output power of the harvester with a six-tooth blunt body improves by ∼43% more than that of the harvester with a traditional square blunt body. The design idea of the proposed harvester provides a direction for the future in-depth study of multidirectional piezoelectric wind energy harvesting.