An apparatus for harvesting electrical energy using a vortex-induced vibration mechanism

Abstract

The present application belongs to offshore platform technical field, specifically a device for collecting electric energy by utilizing vortex-induced vibration mechanism. It comprises a steel plate, a support column, a flexible plate and a piezoelectric material. The steel plate is suspended by the support column at both ends, the height of the steel plate from the ground or platform is H, a flexible plate is arranged on the side opposite to the flow relative to the steel plate surface at 90°, and a sheet-shaped piezoelectric material is arranged on the upper surface of the flexible plate. The present application utilizes the characteristics that a vortex street will be generated in a specific Reynolds number range when a blunt body structure flows around, a horizontally placed flexible plate is fixed behind the blunt body, and a piezoelectric material is attached to the upper surface of the plate. Through the interaction mechanism of vortex and flexible plate, the flexible plate is excited to make stable periodic vibration, thereby providing a new way for the piezoelectric material to continuously collect electric energy.

Description

Technical Field

[0001] This invention belongs to the field of offshore platform technology, specifically a device for harvesting electrical energy using vortex-induced vibration mechanism. Background Technology

[0002] The rapid economic development has led to the increasing depletion of resources and the continuous rise in energy demand, causing people to gradually shift their focus to natural energy sources such as wind and hydropower. my country's vast sea areas contain abundant hydropower resources with enormous development potential. Concentrating efforts on research into key technologies for marine hydropower extraction is of great significance in alleviating my country's growing resource scarcity problem.

[0003] Vortex-induced vibrations in flexible structures are ubiquitous, such as the vibration of pipelines in the ocean, the vibration of flags in the wind, and the flow-induced vibrations of bridges. These vibrations contain enormous amounts of energy that are constantly lost and wasted. If energy conversion devices could be installed to convert environmental vibrations into electrical energy to power microelectronic systems, they could replace batteries. Currently, much research has focused on converting the vibrational energy of flexible bodies into electrical energy, primarily using three methods: electromagnetic induction, electrostatic, and piezoelectric. Piezoelectric energy harvesters, made of piezoelectric materials, have become a research hotspot both domestically and internationally in recent years due to their advantages such as high energy harvesting voltage, simple structure and processing technology, convenient installation, environmental friendliness, long service life, and ease of miniaturization and portability. To expand the application areas of piezoelectric energy harvesters, converting the energy of fluids in nature into electrical energy has always been a goal pursued by researchers. Fluid vibration excites the vibration of a flexible piezoelectric oscillator, causing the piezoelectric material to bend and deform, thereby generating an electric charge. The external circuit of the piezoelectric oscillator collects the charge generated by the oscillator to form a current, thus converting the kinetic energy of fluid flow into electrical energy. The realization of eddy vibration piezoelectric energy harvesting technology can effectively convert the kinetic energy of fluids in nature into electrical energy. Furthermore, its advantages, such as environmental friendliness, cleanliness, durability, simple structure, low cost, and ease of manufacturing and processing, lay the foundation for the commercialization of energy harvesters. Therefore, research on eddy vibration piezoelectric energy harvesting devices has broad application prospects. Summary of the Invention

[0004] The purpose of this invention is to provide a device and design method for collecting electrical energy using the vortex-induced vibration phenomenon of a flexible structure. It utilizes the characteristic that a vortex street is generated when a bluff body structure flows around it within a specific Reynolds number range. A horizontally placed flexible plate is fixed behind the bluff body, and piezoelectric material is attached to the surface of the plate. The interaction mechanism between the vortex and the flexible plate excites the flexible plate to make stable periodic vibrations, thereby providing a new way for piezoelectric materials to continuously collect electrical energy.

[0005] The technical solution to achieve the purpose of this invention is: a device for harvesting electrical energy using eddy vibration mechanism, comprising a steel plate, a support column, a flexible plate, and a piezoelectric material;

[0006] The steel plate is suspended by columns at both ends, with a height H above the ground or platform. A flexible plate is installed on the side of the steel plate opposite to the incoming flow at a 90° angle to the surface of the steel plate. The upper surface of the flexible plate is covered with sheet-like piezoelectric material. The formula for calculating H is as follows:

[0007]

[0008] In the formula, Re is the incoming Reynolds number, ρ is the fluid density, μ is the fluid viscosity coefficient, and V... ∞ It represents the average velocity of the fluid.

[0009] Furthermore, the length, width, and height of the steel plate are 4H, 0.1H, and H, respectively, and the length, width, and height of the two pillars are 0.1H, 0.1H, and 2H, respectively.

[0010] The support column is fixedly connected to the steel plate, and the lower end of the support column is fixed to the ground; the length, width, and height of the flexible plate are 2H, H, and 0.05H, respectively, and one side of the flexible plate is fixedly connected to the steel plate.

[0011] Furthermore, the steel plate is connected to the support column by bolts or welded to the support column; the flexible plate is fixedly connected to the steel plate by bolts.

[0012] Furthermore, the steel plates and supports are made of alloy steel, and the flexible panels are made of ABS resin.

[0013] Furthermore, the support structure is made of reinforced concrete.

[0014] Furthermore, the steel plates and supports are made of Q255 steel, Q275 steel, or Q235 steel; the flexible panels are made of 1,3-butadiene.

[0015] Compared with the prior art, the significant advantages of this invention are:

[0016] This invention is based on the vortex-induced vibration principle of flexible bodies. Using a steel plate as a flow-around bluff body, stable periodic vibrations can be generated through its vortex-induced vibration mechanism. Previous designs for such devices have often used cylinders as the bluff body structure. This structure has high production costs and poor efficiency in generating vortex streets. Other options, such as square columns or flat plates with low characteristic dimensions, also have limited effectiveness in generating vortex streets. This invention adjusts the height of the flow-around plate to ensure stable vortex street generation even under low Reynolds number inflow conditions. Furthermore, the device design has been modified from a longitudinal to a transverse orientation, significantly reducing the drag torque and extending its service life.

[0017] This invention features a detachable bolt connection designed for underwater operations, which allows for the processing of existing supports and steel plates and facilitates future maintenance and replacement.

[0018] This invention uses commonly used alloy steel, which has good economic benefits while meeting design requirements, reduces later maintenance and replacement costs, and helps the realization and promotion of this invention. Attached Figure Description

[0019] Figure 1 This is a three-dimensional schematic diagram of the device for harvesting electrical energy using the eddy vibration mechanism of the present invention.

[0020] Figure 2 This is a front view of the device for harvesting electrical energy using eddy vibration mechanism according to the present invention.

[0021] Figure 3 The left view shows the device for harvesting electrical energy using the eddy vibration mechanism of the present invention.

[0022] Figure 4 This is a top view of the device for harvesting electrical energy using the eddy vibration mechanism of the present invention.

[0023] Figure 5 The time history curves of the displacement at the free end of a flexible beam under the condition of Reynolds number 306 are shown.

[0024] Figure 6 The time history curves of the displacement at the free end of a flexible beam under the condition of Reynolds number 153 are shown.

[0025] Explanation of reference numerals in the attached figures:

[0026] 1-Steel plate, 2-Column, 3-Flexible plate, 4-Piezoelectric material. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings.

[0028] like Figure 1-6 As shown, a design method for a device that utilizes the vortex-induced vibration phenomenon of a flexible structure to harvest electrical energy is described, with the following steps:

[0029] Step (1): Fix the steel plate at both ends with pillars to suspend it in the air, and fix a flexible plate with piezoelectric material attached to the center line of the steel plate;

[0030] Step (2): Design other dimensions in the device based on the height H of the steel plate, and the specific value of H is determined by the incoming Reynolds number;

[0031] Step (3): The steel plate and support column are designed to be made of Q235 alloy steel, and the flexible plate is made of ABS resin (density approximately 1000 kg / m³). 3 ).

[0032] Furthermore, in step (1), the length, width, and height of the steel plate are 4H, 0.1H, and H, respectively, and the length, width, and height of the two supports are 0.1H, 0.1H, and 2H, respectively. The supports are fixedly connected to the steel plate, and the lower end of the supports is fixed to the ground; the length, width, and height of the flexible plate are 2H, H, and 0.05H, respectively, and one side of the flexible plate is fixedly connected to the steel plate.

[0033] Furthermore, the steel plate is connected to the support column by bolts or by welding; the height H of the support column is the visible height above the ground rather than the actual height; the flexible plate is fixedly connected to the steel plate by bolts.

[0034] Furthermore, the specific calculation steps for the height value H of the steel plate structure in step (2) are as follows:

[0035]

[0036] In the formula, Re is the incoming Reynolds number, ρ is the fluid density, μ is the fluid viscosity coefficient, and V... ∞ It represents the average velocity of the fluid.

[0037] The fluid is seawater or river water. When the fluid is seawater, the density is taken as 1.02-1.07 g / cm³. 3 When the fluid is river water, the density is taken as 1.0 g / cm³. 3 .

[0038] The steel plate structure is made of alloy steel; the flexible plate is made of ABS resin.

[0039] The steel plates and supports are made of Q255, Q275, or Q235 steel; the flexible panels are made of 1,3-butadiene. The choice of materials for the steel plates and flexible panels depends on the application environment; reinforced concrete can also be used for the supports.

[0040] For the design of a device that utilizes the vortex-induced vibration phenomenon of a flexible structure to collect electrical energy, the height H of the steel plate is set to 150 mm. To simplify calculations, a two-dimensional model is used to verify the feasibility of the device in collecting electrical energy. The density of seawater is set to 1.02 × 10³ kg / m³, the dynamic viscosity to 1.002 × 10⁻³ kg / (m·s), the density of the flexible body to 1.0 × 10³ kg / m³, the Young's modulus to 5.6 MPa, and the Poisson's ratio to 0.35.

[0041] Example 1

[0042] The device was tested under a low-speed environment with an incoming flow velocity of 2 m / s.

[0043] The Reynolds number is calculated using the parameters above:

[0044]

[0045] Since the incoming Reynolds number is very low, the effect of turbulence on the device can be ignored, so a laminar flow model can be used for its calculation.

[0046] Simulation verification:

[0047] To study the feasibility of this embodiment, a simplified fluid-structure interaction (FSI) simulation of the design was performed using COMSOL Multiphysics software under seawater conditions. The environmental conditions were set as follows: seawater density of 1.02 × 10³ kg / m³, dynamic viscosity of 1.002 × 10⁻³ kg / (m·s), flexible material density of 1.0 × 10³ kg / m³, Young's modulus of 5.6 MPa, and Poisson's ratio of 0.35. The steel plate height H was set to 150 mm, and all other dimensions were determined accordingly. A laminar flow model was used, and the calculation parameters were set to default. The displacement-time history curves of the free end of the flexible plate after calculation are shown in the attached figure. Figure 5 .from Figure 5 It can be seen that the flexible plate begins to vibrate stably after a period of transition, thus proving that the device has good operating capability in a low Reynolds number environment of 306.

[0048] Example 2

[0049] The device was tested under a low-speed environment with an incoming flow velocity of 1 m / s.

[0050]

[0051] Apart from the incoming flow velocity, the same computing environment as in Example 1 was used, and the calculation results are shown in the appendix. Figure 6 As shown. From Figure 6 It can be seen that the flexible plate begins to vibrate stably after a relatively long transition period, which proves that the device can still operate well in a low Reynolds number environment of 153.

Claims

1. A device for harvesting electrical energy using eddy-induced vibration mechanism, characterized in that, The steel plate (1), the support (2), the flexible plate (3) and the piezoelectric material (4) are included. The steel plate (1) is suspended by the supports (2) at both ends, the height of the steel plate from the ground or platform is H, the flexible plate is arranged on the side of the steel plate opposite to the incoming flow and is 90° to the surface of the steel plate, and the upper surface of the flexible plate is provided with the piezoelectric material in the form of a sheet; wherein the calculation formula of H is as follows: where Re is the incoming flow Reynolds number, p is the fluid density, m is the fluid viscosity coefficient, V ∞ denotes the average velocity of the fluid; The length, width and height of the steel plate (1) are 4H, 0.1H and H respectively, and the length, width and height of the two supports (2) are 0.1H, 0.1H and 2H respectively. The support (2) is fixedly connected with the steel plate (1), and the lower end of the support (2) is fixed with the ground; the length, width and height of the flexible plate (3) are 2H, H and 0.05H respectively, and one side of the flexible plate (3) is fixedly connected with the steel plate (1).

2. The apparatus of claim 1, wherein, The steel plate (1) is connected with the support (2) by bolts, or the steel plate (1) is welded with the support (2); and the flexible plate (3) is fixedly connected with the steel plate (1) by bolts.

3. The apparatus of claim 2, wherein, The material of the steel plate (1) and the support (2) is alloy steel, and the material of the flexible plate (3) is ABS resin.

4. The apparatus of claim 3, wherein, The material of the support is reinforced concrete.

5. The apparatus of claim 4, wherein, The material of the steel plate (1) and the support (2) is Q255 steel, Q275 steel or Q235 steel; and the material of the flexible plate is 1,3-butadiene.

Images