Direction-adjustable array type piezoelectric energy harvesting system based on wake flow collaborative self-parameter resonance and power generation method

Abstract

The invention discloses a wake flow collaborative self-parameter resonance-based direction-adjustable array type piezoelectric energy harvesting system and a power generation method. The system comprises a main resonance subsystem and a secondary resonance subsystem, the main system is vertically connected with a bottom support through a hinge, the near end of the secondary system is connected with the main system through a hinge, the far end of the secondary system is connected with a fixed support through a hinge, and the bottom support is a rotatable support. According to the power generation method, fluid generates wake flow after flowing through the first main beam of the main system, the fluid is influenced by the wake flow from the second main beam so as to induce self-parameter internal resonance and common resonance, piezoelectric elements of the main system and piezoelectric elements of the secondary system generate remarkable deformation at the same time, and therefore mechanical energy is efficiently converted into electric energy through the direct piezoelectric effect; in addition, energy from fluids in different directions can be collected through the rotatable support. The energy conversion efficiency is remarkably improved through wake flow cooperation with self-parameter resonance, and an efficient solution is provided for large-scale environment energy collection.

Description

Technical Field

[0001] This invention relates to the field of energy harvesting technology, and more specifically, to an adjustable-direction array-type piezoelectric energy harvesting system and power generation method based on wake-coordinated self-parametric resonance. Background Technology

[0002] In recent years, to address the issues of climate change and fossil fuel depletion, my country's demand for clean and renewable energy has been growing. Wind turbines and hydro turbines have stringent requirements on fluid flow rates and are inefficient at low velocities, while nature contains a large amount of underutilized low-velocity fluid energy. Vortex-induced vibration (V-EV) power generation devices can effectively utilize this energy and are simple in structure and widely applicable. However, the energy capture and collection efficiency of these devices is generally low, posing significant challenges to the practical application of traditional V-EV power generation devices.

[0003] Self-parametric resonance plays a crucial role in the field of nonlinear vibration. If the excitation frequency of the external load is approximately twice the natural frequency of the structure or substructure, the frame structure may experience parametric or self-parametric resonance. Achieving self-parametric resonance enables more efficient energy harvesting and conversion. Existing research indicates that wake effects can induce self-parametric internal resonance and ordinary resonance in G-shaped frame structures. Compared to the case without wake effects, the amplitude of wake-induced self-parametric internal resonance is larger. Under the influence of wake effects, the ordinary resonance region of the hinged structure is significantly increased, and the vibration amplitude is significantly enhanced. However, there is currently no technical solution to apply wake effects to piezoelectric energy harvesting systems. How to apply wake effects to improve piezoelectric energy harvesting systems and study more efficient energy harvesting systems has become an important problem to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems by providing an adjustable-direction array-type piezoelectric energy harvesting system and power generation method based on wake-coordinated self-parametric resonance. This invention significantly improves energy conversion efficiency through wake-coordinated self-parametric resonance, solving the performance limitations of traditional piezoelectric energy harvesting systems caused by narrow linear resonance bandwidth and insufficient excitation intensity, thus providing an efficient solution for large-scale environmental energy harvesting.

[0005] The technical solution of the present invention is described in detail below.

[0006] This invention also provides an adjustable-direction array-type piezoelectric energy harvesting system based on wake-cooperative self-parametric resonance. The system comprises a main resonant subsystem and a secondary resonant subsystem. The main resonant subsystem consists of a main elastic beam component and a piezoelectric conversion element fixedly coupled thereto. The secondary resonant subsystem consists of a secondary elastic beam component and a piezoelectric conversion element fixedly coupled thereto. The main resonant subsystem is fixedly connected to the bottom support via a first connecting structure. The proximal end of the secondary resonant subsystem is connected to the main resonant subsystem via a second connecting structure, and the distal end is connected to the support via a third connecting structure. The secondary resonant subsystems are connected to the top of the main resonant subsystem and form a G-shaped structure. All secondary resonant subsystems face the same direction and do not contact each other. The main resonant subsystem and the secondary resonant subsystems are arranged in an array. During operation, the incoming flow direction is parallel to the array surface. After the fluid flows through the first main elastic beam component of the main resonant subsystem, a wake is generated. Starting from the second main elastic beam component, the wake influences the fluid, thereby inducing intrinsic resonance and ordinary resonance. This causes the piezoelectric elements of the main resonant subsystem and the secondary resonant subsystem to undergo significant deformation simultaneously, thus converting mechanical energy into electrical energy through the positive piezoelectric effect.

[0007] Preferably, the first connecting structure is a fixed hinge, the second connecting structure is a movable hinge, and the third connecting structure is either a fixed hinge or a movable hinge.

[0008] Preferably, the primary resonant subsystem of the first primary elastic beam member through which the fluid flows is selectively connected to or not connected to the secondary resonant subsystem, while the other primary resonant subsystems are connected to the secondary resonant subsystems.

[0009] Preferably, the piezoelectric conversion element is installed at the center of the main elastic beam member and the secondary elastic beam member, respectively.

[0010] Preferably, the main resonant subsystem and the secondary resonant subsystem are arranged in an array.

[0011] Preferably, the ratio of the spacing between adjacent main elastic beam members to the outer diameter of the main elastic beam member is 3:1-12:1.

[0012] Preferably, the bottom support that is fixedly connected to the main resonant subsystem through the first connecting structure is a rotatable support. The outer ring of the rotatable support can rotate 360°. The rotatable support changes direction to cope with the incoming flow from different directions. The rotatable support consists of a central fixed disk and an outer rotatable ring.

[0013] Preferably, the first main elastic beam component of the main resonant subsystem is located at the center of the fixed disk at the center of the support. When the outer ring rotates, all the main elastic beam components of the main resonant subsystem are always on the same straight line, which is parallel to the direction of fluid flow.

[0014] Preferably, the main elastic beam component is made of elastic metal or polymer material, the secondary elastic beam component is made of elastic metal material, and the piezoelectric conversion element is made of piezoelectric ceramic material.

[0015] This invention also provides a power generation method based on wake-coordinated self-parametric resonance, which is implemented based on the above-mentioned system, and the specific steps are as follows: (a) Fluid flows through the material of the first main elastic beam component of the main resonant subsystem; (b) The fluid acts on the material of the first main elastic beam component to generate vortices that alternately fall off from both sides of the material of the main elastic beam component, forming a wake. When the vortex shedding frequency approaches the natural frequency of the main resonant subsystem, the main resonant subsystem resonates. (c) The resonance of the main resonant subsystem enhances the dynamic axial force transmitted to the secondary resonant subsystem. When the frequency of the dynamic axial force is close to twice the natural frequency of the resonant subsystem, the structure undergoes internal resonance. (d) The wake flows through the material of the second main elastic beam and the material of the main elastic beam thereafter. Under the action of the wake, its vibration response is greatly increased. (e) The elastic beam member material under vibration causes the piezoelectric conversion element on it to undergo significant periodic deformation; the piezoelectric conversion element converts mechanical vibration energy into electrical energy output.

[0016] Preferably, in step (a), the fluid is air or liquid water.

[0017] Compared with the prior art, the advantages of the present invention are: This invention innovatively applies wake effects to an array-type piezoelectric energy harvesting system, proposing a novel adjustable-direction array-type piezoelectric energy harvesting system and power generation method based on wake-coordinated self-parametric resonance. When multiple cylinders are arranged in an array, if the incoming flow direction is parallel to the array surface, the cylinders in the array will form a series configuration. The downstream cylinder will be affected by the wake formed by the vortex shedding behind the upstream cylinder, thereby generating a wake-induced vibration phenomenon. The vortex-induced vibration intensity of the wake cylinder is much greater than that of a single cylinder, and the self-parametric resonance it induces is also more intense, thus enabling efficient energy transfer and significant amplification.

[0018] Both the main and subsystems of this system consist of multiple vibration energy harvesting structures, forming an array-type piezoelectric energy harvesting system. By utilizing the synergistic effect of the wake, it significantly increases the maximum self-parameter internal resonant displacement, making fuller use of fluid energy and achieving higher energy conversion efficiency. Furthermore, the bottom disk can freely change direction according to the fluid flow, ensuring that the straight lines connecting all main beams are parallel to the fluid flow direction. Compared to traditional piezoelectric energy harvesting systems, this system can more efficiently harvest vibration energy, has a higher output power density, and can change direction to adapt to fluid flow changes, making energy harvesting more flexible and environmentally adaptable. This system represents a significant breakthrough in flexibility, efficiency, and practicality, providing a novel and reliable solution for clean energy harvesting with broad application prospects. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the self-parametric resonance principle under wake excitation.

[0020] Figure 2 This is a schematic diagram of the structure of the present invention.

[0021] In the diagram: A is the support, A-1 is the supporting beam, A-2 is the rotatable outer ring, A-3 is the central fixed disk, B is the first connecting device, C is the main resonant subsystem, D is the second connecting device, E is the secondary resonant subsystem, F is the third connecting device, C-1-1, C-2-1, C-3-1…Cn-1 are the main elastic beam components, C-1-2, C-2-2, C-3-2…Cn-2 are the first piezoelectric conversion elements; E-1-1, E-2-1, E-3-1…En-1 are the secondary elastic beam components, and E-1-2, E-2-2, E-3-2…En-2 are the second piezoelectric conversion elements. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0023] like Figure 2As shown, an adjustable-direction array-type piezoelectric energy harvesting system based on wake-cooperative self-parametric resonance includes a support A, a first connecting device B, a main resonant subsystem C, a second connecting device D, a secondary resonant subsystem E, and a third connecting device F. Each main elastic beam of the main system is vertically connected to the support via a first hinge. The proximal ends of each secondary elastic beam of the secondary system are connected to the main system via second hinges, and the distal ends of the secondary systems are connected to a fixed support via third hinges. The main resonant subsystem includes main elastic beam components C-1-1, C-2-1, C-3-1…Cn-1 and corresponding first piezoelectric conversion elements C-1-2, C-2-2, C-3-2…Cn-2. The secondary resonant subsystem includes secondary elastic beam components E-1-1, E-2-1, E-3-1…En-1 and corresponding second piezoelectric conversion elements E-1-2, E-2-2, E-3-2…En-2. An adjustable concentrated mass block is provided at the end of each secondary elastic beam component.

[0024] The power generation method of the system is implemented as follows: After the fluid flows through the first main beam of the main system, vortices are generated on both sides of the main beam and alternately fall off, forming a wake. By pre-adjusting the concentrated mass blocks of each subsystem, the main system and each subsystem have specific natural frequency distributions. When the vortex shedding frequency approaches the system's natural frequency, the system resonates. The resonance of the main system enhances the dynamic axial force transmitted to the subsystems. When the frequency of the dynamic axial force approaches twice the natural frequency of the subsystem, the structure will undergo self-parametric resonance. The wake flows through the second main beam and subsequent main beams. Under the action of the wake, its vibration response is greatly increased. The elastic beam structure under vibration drives the piezoelectric elements on it to undergo significant periodic deformation; the piezoelectric elements convert mechanical vibration energy into electrical energy output.

[0025] In practical applications, the bottom rotating device can be used to handle fluids in different directions, the stiffness of the system can be changed according to the different properties of the fluid, and the configuration of the mass block can be changed according to the change of excitation frequency, so that the device can continuously and efficiently generate electrical energy in different flow fields.

[0026] Example 1

[0027] The present invention is further illustrated below with reference to specific embodiments. However, it should be understood that these embodiments are for illustrative purposes only and do not constitute a limitation on the scope of the invention. Test methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0028] according to Figure 2 The adjustable-direction array-type piezoelectric energy harvesting system based on wake-cooperative self-parametric resonance is shown to generate piezoelectric power. The main beams are made of PVC round pipe, the secondary beams are made of spring steel, and the piezoelectric elements are made of piezoelectric ceramic. Each main elastic beam in the main system is vertically connected to the support via a first hinge. The proximal ends of each secondary elastic beam in the secondary system are connected to the main system via a second hinge, and the distal ends are connected to the fixed support via a third hinge. The first main beam is only used to generate a wake and is not connected to the main system. Water is used as the fluid, with a constant water level of 0.405 m and a flow velocity ranging from 0.31 to 0.96 m / s. The natural frequency of the main system is 8.8 Hz, and the natural frequency of the secondary system is 4.4 Hz. When the ratio of the spacing of the main beams to the outer diameter of the main beams is 9, the displacement ratio (A / D) can reach a maximum of 18.76; when the ratio of the spacing of the main beams to the outer diameter of the main beams is 6, the displacement ratio (A / D) can reach a maximum of 52.6. The maximum self-parameter internal resonance displacement generated under the wake effect is 55.29% larger than that without wake. The maximum displacement when the subsystem has self-parameter internal resonance is 4 times that of the maximum ordinary resonance displacement. Compared with the power generation efficiency when the single system has ordinary resonance, the power generation efficiency is increased by about 5 times.

[0029] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A tunable directional arrayed piezoelectric energy harvesting system based on wake co-oscillating self-parameter resonance, characterized in that, The system comprises a main resonant subsystem and a secondary resonant subsystem; the main resonant subsystem is composed of a main elastic beam member and a piezoelectric conversion element fixedly coupled thereto, and the secondary resonant subsystem is composed of a secondary elastic beam member and a piezoelectric conversion element fixedly coupled thereto; the main resonant subsystem is fixedly connected with a bottom support through a first connecting structure, and the secondary resonant subsystem is connected with the main resonant subsystem through a second connecting structure at a proximal end and connected with the support through a third connecting structure at a distal end; the secondary resonant subsystem is connected at a top of the main resonant subsystem and forms a G-shaped structure, all the secondary resonant subsystems have the same orientation and do not contact each other, and the main resonant subsystem and the secondary resonant subsystem are arranged in an array. During operation, the flow direction is parallel to the array surface, and the fluid flows through the first main elastic beam member of the main resonant subsystem to generate a wake flow, and the second main elastic beam member and the subsequent main elastic beam members are affected by the wake flow to induce self-parameter internal resonance and common resonance, so that the piezoelectric elements of the main resonant subsystem and the secondary resonant subsystem simultaneously generate significant deformation to convert mechanical energy into electrical energy through the piezoelectric effect.

2. The adjustable directional arrayed piezoelectric energy-harvesting system based on wake co- resonator self-parameter according to claim 1, wherein, The first connecting structure is a fixed hinge, the second connecting structure is a movable hinge, and the third connecting structure is a fixed hinge or a movable hinge.

3. The adjustable directional arrayed piezoelectric power harvesting system based on wake co- resonator self-parameter according to claim 1, wherein, The first main elastic beam member of the main resonant subsystem through which the fluid flows is selectively connected with or not connected with the secondary resonant subsystem, and the other main resonant subsystems and the secondary resonant subsystems are all connected.

4. The adjustable directional arrayed piezoelectric power harvesting system based on wake co- sympathetic self-parameter resonance of claim 1, wherein, The piezoelectric conversion elements are respectively installed at the center positions of the main elastic beam members and the secondary elastic beam members.

5. The adjustable directional arrayed piezoelectric power harvesting system based on wake co- sympathetic self-parameter resonance of claim 1, wherein, The ratio of the interval between the adjacent main elastic beam members to the outer diameter of the main elastic beam member is 3:1-12:

1.

6. The adjustable directional arrayed piezoelectric power harvesting system based on wake co- sympathetic self-parameter resonance of claim 1, wherein, The bottom support fixedly connected with the main resonant subsystem through the first connecting structure is a rotatable support, and the outer ring of the rotatable support can rotate by 360°. The rotatable support is composed of a center fixed disc and an outer rotatable ring.

7. The adjustable directional arrayed piezoelectric power harvesting system based on wake co- sympathetic self-parameter resonance according to claim 6, wherein, The first main elastic beam member of the main resonant subsystem is located at the center of the center fixed disc, and all the main elastic beam members of the main resonant subsystem are always on the same straight line during the rotation of the outer ring. The straight line is parallel to the direction of the fluid flow.

8. The adjustable directional arrayed piezoelectric power harvesting system based on wake co- sympathetic self-parameter resonance of claim 1, wherein, The main elastic beam member is made of elastic metal material or polymer material, the secondary elastic beam member is made of elastic metal material, and the piezoelectric conversion element is made of piezoelectric ceramic material.

9. A method of generating electricity based on the wake synergy self-parametric resonance, implemented on the basis of the system according to any one of claims 1-8, characterized by the fact that, The specific steps are as follows: (a) The fluid flows through the first main elastic beam member of the main resonant subsystem; (b) The fluid acts on the first main elastic beam member to generate vortexes which are alternately shed from both sides of the main elastic beam member material to form a wake flow. When the shedding frequency approaches the natural frequency of the main resonant subsystem, the main resonant subsystem resonates; (c) The resonance of the main resonant subsystem enhances the dynamic shaft force transmitted to the secondary resonant subsystem. When the frequency of the dynamic shaft force approaches twice the natural frequency of the resonant subsystem, the structure resonates internally; (d) The wake flow flows through the second main elastic beam member and the subsequent main elastic beam members, and the vibration response of the main elastic beam members is greatly increased under the action of the wake flow; (e) The piezoelectric conversion elements on the elastic beam members in the vibration state are obviously deformed periodically, and the piezoelectric conversion elements convert the mechanical vibration energy into electrical energy output.

10. The method of power generation based on wake co-operating self-parametric resonance according to claim 9, characterized in that, In step (a), the fluid is air or liquid water.

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