Piezoelectric Wind Energy Harvester Research Articles

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.

Design, performance evaluation and calibration of an indirectly-excited piezoelectric wind energy harvester via a double-bluffbody exciter

Using piezoelectric wind energy harvester to harvest energy from fluids has been an effective way to power wireless sensing systems in the last decade. In order to solve the problems of low reliability, poor environmental adaptability and narrow operating bandwidth of existing piezoelectric wind energy harvesters, a piezoelectric wind energy harvester with a double-bluffbody exciter (DE-PWEH) is proposed in this research. By summarizing the disadvantages of traditional piezoelectric wind energy harvester with upwind structure, a downwind structure was adopted to improve the ability of PWEH to adapt to high wind speed environment. In order to further improve the reliability of the DE-PWEH, a wind isolation structure and an indirect excitation structure was adopted, which means the piezoelectric element was installed inside a cylindrical shell. Therefore, this 2-DOF indirectly excited DE-PWEH could possess both high reliability and broad working bandwidth. To verify the principle feasibility and design regarding the proposed DE-PWEH, a prototype of the DE-PWEH was fabricated and tested in terms of output and operating bandwidth. The results showed that the relative size and position of the adjustable plate and cylindrical shell brought significant effects on the output and operating bandwidth. When the distance-diameter ratio was 0.6, the width-diameter ratio was 1 and the height ratio was 1, the maximum output voltage was 90.35 V and the critical wind speed was 0.96 m/s. The maximum increase of the critical wind speed was 550%, and the minimum was −85.67%. With a wind speed of 15 m/s and the optimal load resistance of 2000 kΩ, a maximum power of 2.57 mW was attained. In order to quantitatively study the performance of DE-PWEH, a data fitting method based on polynomial was proposed for the first time to calibrate PWEH performance. The sixth order polynomial fitting equation can be used to characterize the output characteristics of DE-PWEH. And in practice, 80 LEDs in series were successfully driven by the DE-PWEH. The DE-PWEH could charge the 470 μF, 1000 μF, 2200 μF and 3000 μF commercial capacitors to 2 V in 60 s, 128 s, 340 s, and 400 s, respectively.

A review of piezoelectric energy harvesters for harvesting wind energy

Microelectromechanical systems (MEMS) powered by conventional batteries are disadvantaged in terms of scope of application and environmental friendliness because their power sources need to be replaced regularly and have the risk of polluting the environment. Piezoelectric technology provides a solution for harvesting clean energy such as wind energy from the environment, achieving self-supply of electrical energy for MEMS, and meeting the requirement of without management and maintenance after installation. An overview of piezoelectric wind energy harvesting can help to connect the MEMS field and meet its self-supply needs. This paper presents a comprehensive review of state-of-the-art advances in piezoelectric wind energy harvesters (PWEH). The classification of piezoelectric materials is briefly introduced. The principle of its operation is introduced. It is divided into five categories by structure: bluff body, airfoil, flag, wind concentrator, and wind turbine structures. The research status of harvester has been discussed from four perspectives: structure, application, theoretical modeling, and signal processing. The existing literature is integrated, and the future development directions in three aspects: expanding application area, improving adaptive capabilities, and application-oriented system design are proposed. This paper provides references for people in the industry who are committed to structural innovation and performance enhancement.

Research on a rotary piezoelectric wind energy harvester with bilateral excitation.

This paper describes a rotary piezoelectric wind energy harvester with bilateral excitation (B-RPWEH) that improves power generation performance. The power generating unit in the current piezoelectric cantilever wind energy harvester was primarily subjected to a periodic force in a single direction. The B-RPWEH adopted a reasonable bilateral magnet arrangement, thus avoiding the drawbacks of limited piezoelectric cantilever beam deformation and unstable power generation due to unidirectional excitation force. The factors affecting the power generation were theoretically analyzed, and the natural frequency and excitation force of the piezoelectric cantilever have been simulated and analyzed. A comprehensive experimental research method was used to investigate the output performance. The B-RPWEH reaches a maximum output voltage of 20.48Vpp when the piezoelectric sheet is fixed at an angle of 30°, the Savonius turbine number is 3, and the magnet diameter is 8mm. By adjusting the fixed angle of the piezoelectric sheet, the number of Savonius wind turbine blades, and the magnet diameter, the maximum voltage is increased by 52.38%, 4.49%, and 245.95%, respectively. The output power is 24.5 mW with an external resistor of 8 kΩ, and the normalized power density is 153.14 × 10-3 mW/mm3, capable of powering light-emitting diodes (LEDs). This structure can drive wireless networks or low-power electronics.

Piezoelectric wind energy harvesting from vortex- induced vibrations of an elastic beam

Piezoelectric wind energy harvesting from vortex- induced vibrations of an elastic beam

Harvesting airflow energy from circular cylinder wake via a thin polyvinylidene fluoride film

To improve the characteristics of airflow energy harvesting, this paper presents a new piezoelectric wind energy harvester (PWEH), in which a polyvinylidene fluoride (PVDF) film was directly located in the wake of the circular cylinder. Four important parameters were independently varied for detailed experimental investigations: wind speed, spacing ratio for the distance between the center of the circular cylinder and the tip of the PVDF film to the circular cylinder diameter, diameter of the circular cylinder, and load resistance. The results indicated that the designed PWEH performed optimally with the occurrence of resonance, maintaining a relatively high output when significantly exceeding the resonance wind speed. The PVDF film inhibited the vortex shedding of the circular cylinder, which weakened with increasing spacing ratio. The optimum value of the spacing ratio should be approximately 2.5, which yields an effective coupling between the vortex and structure. The diameter of the circular cylinder played an important role in determining the output power. The match between the load resistance and PWEH also contributed to the high-level performance. Moreover, with an increase in the diameter of the circular cylinder, the increasing blockage ratio unexpectedly enhanced the vortex shedding frequency and decreased the theoretical resonance wind speed, which provided a new orientation for improving the performance of such PWEHs.

Research on nonlinear isometric L-shaped cantilever beam type piezoelectric wind energy harvester based on magnetic coupling.

Harvesting wind energy using piezoelectric materials is expected to be an alternative solution for powering wireless sensing networks. This paper proposed a nonlinear isometric L-shaped cantilever beam type piezoelectric wind energy harvester based on magnetic coupling (L-PWEH). The transducer consists of an array of equidistant L-shaped piezoelectric vibrators that are sealed inside the shell. It greatly improves the equivalent piezoelectric coefficient, robustness, and wind speed range for reliable operation. Theoretical and simulation analyses of the structural parameters related to the widening of the L-PWEH were performed. The prototype was built and the experimental system was constructed to verify the feasibility of the L-PWEH and the results of the analyses. Experiments have shown that increasing the magnetic force, additional springs, and the appropriate quantity of excitation magnets can effectively increase the output voltage and widen the wind speed range at high voltage output. When the wind speed is 16.35m/s and the load resistance is 2 MΩ, the best output power of the piezoelectric vibrator is 142.3 µW. At this time, the height of the middle excitation magnet of the prototype is 12mm, the number is 5, and the wire diameter of the additional spring is 1mm. The prototype can successfully make the electronics work properly.

Enhancing the Performance of Piezoelectric Wind Energy Harvester Using Curve-Shaped Attachments on the Bluff Body.

This paper presents a piezoelectric wind energy harvester that operates by a galloping mechanism with different shaped attachments attached to a bluff body. A comparison is made between harvesters that consist of different shaped attachments on a bluff body; these include triangular, circular, square, Y-shaped, and curve-shaped attachments. Simulation of the pressure field and the velocity field variation around the different shaped bluff bodies is performed and it is found that a high pressure difference creates a high lift force on the bluff body with curve-shaped attachments. A theoretical model based on a galloping mechanism is presented, which is verified by experiments. It is observed that the proposed harvester with curve-shaped attachments provides the best performance, where the harvester with a curve-shaped attachments provides the highest voltage and power output compared to the other shaped harvesters examined in this study. This paper provides a new concept for improving the power performance of the piezoelectric wind energy harvesters with modifications made on the bluff body.

An enhanced galloping-based piezoelectric energy harvester with non-rotational bluff body

This study proposes a bluff body non-rotational galloping-based piezoelectric wind energy harvester (BNRGH) for overall output performance enhancement. The bluff body used in this structure is designed to be available to rotate with respect to the free end of two cantilever beams by the connection of rotatable hinges. A series of performance comparisons are conducted experimentally in a wind tunnel between the proposed structure and the conventional galloping-based piezoelectric energy harvester, which commonly configured with a single beam. The results show that the proposed structure is capable of preventing the variation of the attack angle due to the self-rotation of the bluff body caused by the deflection of a common single beam, thus avoiding the amplitude saturation of the bluff body at a higher wind velocity range. It shows that the output voltage remains a continuous linear increase within elastic deformation range of the cantilever beam even in higher wind velocity range, which is helpful in accomplishing a broad wind range for a significant improvement of the overall performance. Overall, the proposed BNRGH provides a design guidance for a small size galloping-based energy harvester to achieve an excellent output performance, which holds great potential to promote its application in wireless node networks for self-power supply.