Piezoelectric energy harvesting device based on wind-induced vibration

Abstract

The present application discloses a piezoelectric energy capture device based on wind-induced vibration to solve the problem of low adaptability of existing low-speed piezoelectric energy capture devices to environmental wind speed. The present application provides a piezoelectric energy capture device based on wind-induced vibration, the piezoelectric energy capture device comprising a first airfoil and a second airfoil; and a connecting member, the first airfoil and the second airfoil are respectively rotatably arranged at both ends of the connecting member, and respectively form an angle with the connecting member. The present application can adjust the angle between the first airfoil and the second airfoil on the connecting member by rotation, thereby adjusting the angle of attack of the first airfoil and the second airfoil. The present application sets a double-wing blunt body structure with adjustable angle of attack to achieve different flow-induced vibration mechanisms corresponding to different angles of attack of the device, thereby being suitable for wind energy capture and utilization at different wind speeds, that is, comprehensively utilizing the advantages of the two vibrations at low and high speeds, namely, vortex-induced vibration at low wind speed and galloping vibration at high wind speed, and improving the comprehensive performance of the output.

Description

Technical Field

[0001] The present application relates to the technical field of wind power generation, and in particular to a piezoelectric energy capture device based on wind-induced vibration. Background Art

[0002] With the rise of new concepts such as smart cities and intelligent manufacturing, modern Internet of Things (IoT), wireless sensor networks (WSN), and microelectromechanical systems (MEMS) have seen widespread development and application. However, the primary energy source for these low-power electronic products is still chemical batteries, which pose significant challenges such as environmental pollution, difficulty in recycling, and the need for regular replacement. Wind energy is one of the earliest renewable energy sources to be harvested and utilized by humans. Due to its clean, environmentally friendly nature and abundant reserves, it has been widely researched and applied. Compared with traditional wind turbines, wind energy harvesting devices based on flow-induced vibration (FIV) have the advantage of low starting wind speeds, making them suitable for harvesting and utilizing low-speed wind energy. Piezoelectric materials are functional materials that can convert mechanical energy into electrical energy, and their direct piezoelectric effect can be used to achieve this conversion. Therefore, using piezoelectric materials to harvest low-speed wind energy, replacing traditional chemical batteries to power these nodes, has become a promising and valuable research direction.

[0003] The operating principles of flow-induced vibration-based piezoelectric low-speed wind energy harvesters (FIVPWEHs) mainly fall into two categories: vortex-induced vibration (VIV) and galloping. VIV-based wind energy harvesters have high energy collection efficiency within a certain wind speed range (the frequency-locking zone), but this frequency-locking zone is generally narrow, and the output power drops sharply beyond the frequency-locking zone. Galloping-based wind energy harvesters, on the other hand, have the characteristic of increasing output power with increasing wind speed. However, compared with VIV-based wind energy harvesters, their starting wind speed is generally higher, making them unable to fully harvest low-speed wind energy from the environment. However, wind in nature is non-uniform and non-stationary, meaning that wind speed varies over time. Therefore, improving the adaptability of low-speed wind energy harvesters to environmental wind speeds so that they can continuously and stably harvest wind energy from nature has become a key design goal for these energy harvesters.

[0004] Existing piezoelectric low-speed wind energy capture devices based on vortex-induced vibration and galloping vibration only have high output power within a specific wind speed range, and the energy utilization rate of wind energy in the environment is still low, which greatly limits the engineering application of such wind energy capture devices.

[0005] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0006] The technical problem to be solved by the present application is to provide a piezoelectric energy capture device based on wind-induced vibration in response to the deficiencies of the existing technology, so as to solve the problem that the existing low-speed piezoelectric energy capture device has low adaptability to the ambient wind speed.

[0007] In order to solve the above technical problems, the first aspect of the embodiments of the present application provides a piezoelectric energy capture device based on wind-induced vibration, wherein the piezoelectric energy capture device includes:

[0008] a first airfoil and a second airfoil;

[0009] and a connecting member, wherein the first airfoil and the second airfoil are respectively rotatably arranged at two ends of the connecting member and form an angle with the connecting member respectively.

[0010] In one implementation, the energy capture device further includes:

[0011] A cantilever arm, the cantilever arm being fixedly arranged on the connecting member;

[0012] A piezoelectric sheet is fixedly arranged on the cantilever arm.

[0013] In one implementation, the first airfoil and the second airfoil are arranged in mirror symmetry along the central axis of the connecting member.

[0014] In one implementation, a rotation axis groove is provided at the chord-wise and span-wise center positions of the first airfoil and the second airfoil, and positioning holes are provided at both ends of the rotation axis groove; bearings corresponding to the positioning holes are provided on both ends of the connecting member, and the bearings rotate frictionally in the positioning holes.

[0015] In one implementation, an elastic member is provided in the positioning hole, and the bearing is connected to the positioning hole via the elastic member.

[0016] In one implementation, a connection hole is provided on one side of the connection member, and the cantilever arm is fixedly provided on the connection hole.

[0017] A second aspect of the present application provides a method for capturing piezoelectric energy from wind-induced vibrations, including the piezoelectric energy capture device based on wind-induced vibrations as described above. The capture method includes:

[0018] When it is determined based on local seasonal climate characteristics and ambient wind field data that the current wind speed is within a suitable wind speed range for vortex-induced vibration, adjusting the angle of attack of the piezoelectric energy capture device based on wind-induced vibration to a value greater than a critical value;

[0019] When the current wind speed is determined to be in a suitable galloping wind speed range based on local seasonal climate characteristics and ambient wind field data, the angle of attack of the piezoelectric energy capture device based on wind-induced vibration is adjusted to a range from zero to a critical value.

[0020] In one implementation, after determining based on local seasonal climate characteristics and ambient wind field data that the current wind speed is within a suitable wind speed range for vortex-induced vibration, before adjusting the angle of attack of the piezoelectric energy capture device based on wind-induced vibration to a value greater than a critical value, the capture method further includes:

[0021] The critical value is determined based on the piezoelectric energy harvesting device.

[0022] In one implementation, the capture method further includes:

[0023] When it is determined based on local seasonal climate characteristics and ambient wind field data that the current wind speed is in a wind speed range suitable for vibration suppression, the angle of attack of the piezoelectric energy capture device based on wind-induced vibration is adjusted to a value less than zero.

[0024] Beneficial effect: The present application can adjust the angle between the first airfoil and the second airfoil in the connecting member by rotation, thereby adjusting the angle of attack α of the first airfoil and the second airfoil. The present application realizes that different angles of attack of the device correspond to different flow-induced vibration mechanisms by setting a double-airfoil blunt body structure with adjustable angle of attack, thereby being suitable for capturing and utilizing wind energy at different wind speeds, that is, comprehensively utilizing the advantages of the two vibrations at low and high speeds, namely vortex-induced vibration at low wind speed and galloping vibration at high wind speed, and the comprehensive performance of the output is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without inventive work.

[0026] Figure 1 This is a schematic structural diagram of the piezoelectric energy capture device based on wind-induced vibration provided in this application.

[0027] Figure 2 This is a structural schematic diagram of the attack angle in the piezoelectric energy capture device based on wind-induced vibration provided in this application.

[0028] Figure 3 This is a curve diagram showing the change of the dimensionless amplitude of the first airfoil and the second airfoil with wind speed in the piezoelectric energy capture device based on wind-induced vibration provided in this application.

[0029] Figure 4 This is a schematic structural diagram of the first airfoil in the piezoelectric energy capture device based on wind-induced vibration provided in this application.

[0030] Figure 5This is a schematic diagram of the structure of the connecting parts in the piezoelectric energy capture device based on wind-induced vibration provided in this application.

[0031] Figure 6 This is a schematic diagram of the working modes of the piezoelectric energy capture device based on wind-induced vibration at different attack angles in the piezoelectric energy capture method based on wind-induced vibration provided in this application.

[0032] Figure 7 This is a schematic flow chart of the piezoelectric energy capture method for wind-induced vibrations provided in this application.

[0033] In the figure: 1. First airfoil; 2. Connector; 3. Second airfoil; 4. Cantilever arm; 5. Piezoelectric plate; 6. Positioning hole; 7. Rotating shaft groove; 8. Bearing; 9. Connecting hole; 10. Shedding vortex; 11. Centerline. DETAILED DESCRIPTION

[0034] This application provides a piezoelectric energy capture device based on wind-induced vibrations. To make the purpose, technical solutions, and effects of this application more clear and explicit, the application is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only intended to explain this application and are not intended to limit this application.

[0035] It will be understood by those skilled in the art that, unless expressly stated otherwise, the singular forms "a", "an", "said" and "the" used herein may also include the plural forms. It should be further understood that the term "comprising" used in the specification of the present application refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be intermediate elements. In addition, "connected" or "coupled" as used herein may include wireless connections or wireless couplings. The term "and / or" used herein includes all or any units and all combinations of one or more associated listed items.

[0036] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0037] The application content will be further explained below through description of embodiments in conjunction with the accompanying drawings.

[0038] The existing vortex-induced vibration has a frequency-locked region in the low wind speed range. At this time, the amplitude is large and the output power is also large. However, once the wind speed increases beyond the frequency-locked resonance region, the amplitude will drop sharply and the output power will also decrease. The amplitude of galloping vibration continues to increase with the increase of wind speed, but the amplitude is lower at low wind speeds, so the output at low wind speeds is also lower.

[0039] Based on the existing technical background, such as Figure 1 As shown, the first aspect of this embodiment provides a piezoelectric energy capture device based on wind-induced vibration, the piezoelectric energy capture device includes a first airfoil 1, a second airfoil 3 and a connecting member 2, the first airfoil 1 and the second airfoil 3 are respectively rotatably arranged at the two ends of the connecting member 2, and form an angle with the connecting member 2 respectively, and the angle between the first airfoil 1 and the second airfoil 3 on the connecting member 2 can be adjusted by rotation, thereby adjusting the angle of attack α of the first airfoil 1 and the second airfoil 3, wherein, as Figure 2 As shown, the angle of attack α is the angle between the central axis of the first airfoil 1 or the second airfoil 3 and the rotation position of the connecting member 2 in the horizontal direction. In actual experimental operation, the angle of attack α of the first airfoil 1 and the second airfoil 3 needs to be adjusted to the same, such as Figure 3 As shown in the figure, the dimensionless amplitude of the bluff body varies with wind speed for the first airfoil 1 or the second airfoil 3 at different angles of attack α, where A is the maximum amplitude of the biplane bluff body and D is the characteristic dimension of the biplane bluff body. The calculated data can be obtained through simulation software based on computational fluid dynamics, such as Ansys Fluent. As can be seen from the figure, the dimensionless amplitude of the biplane bluff body varies in different wind speed ranges for the same angle of attack α; and different angles of attack also vary in the same wind speed range. This embodiment, by adopting a biplane bluff body structure with adjustable angle of attack, achieves different flow-induced vibration mechanisms corresponding to different angles of attack of the device, thereby being suitable for capturing and utilizing wind energy at different wind speeds. In other words, it comprehensively utilizes the advantages of two types of vibration at low and high wind speeds: vortex-induced vibration at low wind speeds and galloping vibration at high wind speeds, thereby improving the overall output performance.

[0040] In one embodiment, if Figure 3 As shown in the curve of the dimensionless amplitude of the bluff body with wind speed, the smaller the characteristic dimension D of the double-wing bluff body is, the larger the dimensionless amplitude is. In order to increase the dimensionless amplitude, in addition to selecting the shapes of the first airfoil 1 and the second airfoil 3, other slender structures can also be used for design. In this embodiment, Figure 2As shown, taking the first airfoil 1 and the second airfoil 3 as examples, this embodiment fully utilizes the aerodynamic characteristics of the airfoil at different angles of attack for energy collection. At small angles of attack, the airfoil surface is essentially an attached flow, with vortex shedding primarily concentrated at the trailing edge. At large angles of attack, however, the airfoil surface undergoes extensive separation, with vortex shedding gradually extending from the trailing edge to the upper wing surface. In these two cases, the frequency and intensity of the shedding vortices 10 differ, and thus the dynamic characteristics generated by the excitation of the cantilever beam are also different.

[0041] In one embodiment, if Figure 1 As shown, the energy capture device further includes a cantilever arm 4 and a piezoelectric piece 5. The cantilever arm 4 is fixedly arranged on the connecting member 2, and the piezoelectric piece 5 is adhered to the root of the cantilever arm 4 away from the connecting member 2, as shown in FIG. Figure 2 As shown, when natural wind encounters a double-wing bluff body, a periodic shedding vortex 10 is formed at the trailing edge of the double-wing bluff body. The pressure distribution on the surface of the double-wing bluff body changes accordingly, and a periodic excitation force acts on the double-wing bluff body, causing the cantilever beam structure to vibrate regularly. In this case, the piezoelectric piece 5 attached to the root of the cantilever beam will follow the deformation of the root of the cantilever beam, generate periodic strain, and then output a periodic voltage.

[0042] In one embodiment, in order to prevent the cantilever beam vibration from causing plastic deformation biased to one side, the first airfoil 1 and the second airfoil 3 are symmetrically arranged along the central axis 11 of the connecting member 2, and the attack angle of the double-airfoil blunt body is also mirror-symmetrically configured along the central axis 11 of the connecting member 2 to ensure that the balance point of the cantilever beam vibration is located on the central axis 11.

[0043] In one embodiment, if Figure 1 、 Figure 4 、 Figure 5 As shown, the first airfoil 1 and the second airfoil 3 are provided with a shaft groove 7 at the chord-wise and span-wise center positions, and positioning holes 6 are provided at both ends of the shaft groove 7. Bearings 8 corresponding to the positioning holes 6 are provided on both ends of the connecting member 2, and the bearings 8 rotate frictionally in the positioning holes 6. Due to the friction between the bearings 8 and the positioning holes 6, when adjusting the rotation angle of the first airfoil 1 and the second airfoil 3 respectively with the connecting member 2, a certain force needs to be applied to drive the first airfoil 1 or the second airfoil 3 to rotate to a specific position of the connecting member 2. When no force is applied manually, the first airfoil 1 and the second airfoil 3 are respectively fixed to the connecting member 2 and do not rotate due to the action of wind.

[0044] Furthermore, an elastic member (not shown in the figure) is provided in the positioning hole 6, and the bearing 8 is connected to the positioning hole 6 via the elastic member. By providing the elastic member, on the one hand, the friction between the positioning hole 6 and the bearing 8 can be further improved, so that relative movement is not easy to occur between the positioning hole 6 and the bearing 8, thereby preventing the first airfoil 1 and the second airfoil 3 from rotating due to the action of wind force, resulting in changes in the angle of attack on the first airfoil 1 and the second airfoil 3 and affecting energy capture; on the other hand, since it is necessary to rotate the bearing 8 in the positioning hole 6 to adjust the angle of attack according to different wind speed ranges, the bearing 8 is easily damaged during long-term rotation and adjustment. Therefore, by installing the elastic member, the positioning hole 6 can be protected from damage, and only the elastic member can be damaged. When the elastic member is damaged, only the elastic member needs to be replaced, and there is no need to replace the entire piezoelectric energy capture device, thereby improving the service life of the entire device.

[0045] In one embodiment, if Figure 1 、 Figure 4 、 Figure 5 As shown, a connection hole 9 is provided on one side of the connection member 2, and the cantilever arm 4 is fixed to the connection hole 9 by screw riveting or gluing.

[0046] In summary, the first aspect of this embodiment provides a piezoelectric energy capture device based on wind-induced vibration, wherein the piezoelectric energy capture device includes a first airfoil 1, a second airfoil 3, and a connector 2. The first airfoil 1 and the second airfoil 3 are respectively rotatably arranged at the two ends of the connector 2, and form an angle with the connector 2 respectively. The angle between the first airfoil 1 and the second airfoil 3 on the connector 2 can be adjusted by rotation, thereby adjusting the angle of attack α of the first airfoil 1 and the second airfoil 3, wherein, as Figure 2 As shown, the angle of attack α is the angle between the central axis of the first airfoil 1 or the second airfoil 3 and the rotational position of the connector 2 in the horizontal direction. This embodiment utilizes a double-wing bluff structure with an adjustable angle of attack to achieve different flow-induced vibration mechanisms corresponding to different angles of attack of the device, thereby being suitable for capturing and utilizing wind energy at different wind speeds. In other words, the advantages of two types of vibration at low and high wind speeds are comprehensively utilized, namely, vortex-induced vibration at low wind speeds and galloping vibration at high wind speeds, thereby improving the overall output performance.

[0047] The second aspect of this embodiment further provides a piezoelectric energy capture method based on wind-induced vibration, including the piezoelectric energy capture device based on wind-induced vibration as described above, such as Figure 6 、 Figure 7 As shown, the capture method includes:

[0048] S10, when it is determined based on local seasonal climate characteristics and ambient wind field data that the current wind speed is within a suitable wind speed range for vortex-induced vibration, adjusting the angle of attack of the piezoelectric energy capture device based on wind-induced vibration to a value greater than a critical value;

[0049] S20. When it is determined based on local seasonal climate characteristics and ambient wind field data that the current wind speed is in a suitable range for galloping wind speeds, the angle of attack of the piezoelectric energy capture device based on wind-induced vibration is adjusted to a range from zero to a critical value.

[0050] Specifically, the wind speed range suitable for vortex-induced vibration is the frequency-locking range, and the energy collection efficiency is relatively high within the frequency-locking range; the wind speed range suitable for galloping vibration is the galloping vibration starting range. After numerical simulation and wind tunnel test verification of the piezoelectric energy capture device based on wind-induced vibration, it was found that the airfoil angle of attack α of the device has a critical value α0, and has the following working mode:

[0051] When the bifocal angle of attack α>α0, the cantilever beam with a bifocal bluff attached to the free end exhibits vortex-induced vibration characteristics. This means that within the lower wind speed range, there is a frequency-locking region, where the cantilever beam's amplitude is large and the vibration frequency is locked to the cantilever beam's natural frequency. At this time, the strain on the piezoelectric plate at the cantilever beam's root is also large, resulting in a high output voltage. However, when the bifocal angle of attack 0<α<α0, the cantilever beam with a bifocal bluff attached to the free end exhibits galloping characteristics. This means that the cantilever beam's amplitude increases with increasing wind speed, and the vibration frequency is near the cantilever beam's natural frequency. At higher wind speeds, the cantilever beam's amplitude is larger, resulting in greater strain at the root and a higher output voltage. Therefore, after obtaining the device's critical value α0, the device's angle of attack can be adjusted based on the current wind speed range, setting an appropriate angle of attack for the bifocal bluff body and optimizing the device's output power to improve energy utilization in low-speed wind farms.

[0052] In one embodiment, after determining based on local seasonal climate characteristics and ambient wind field data that the current wind speed is within a suitable vortex-induced vibration wind speed range, before the step of adjusting the angle of attack of the piezoelectric energy capture device based on wind-induced vibration to a value greater than a critical value, the capture method further comprises:

[0053] S11. Determine a critical value based on the piezoelectric energy capture device.

[0054] Specifically, the critical value is the maximum attack angle value of the piezoelectric energy capture device, and the critical value can be obtained by importing the piezoelectric energy capture device based on wind-induced vibration into a simulation calculation based on computational fluid dynamics software, such as Ansys Fluent.

[0055] In one embodiment, the capturing method further comprises:

[0056] S21. When it is determined based on local seasonal climate characteristics and environmental wind field data that the current wind speed is in a wind speed range suitable for vibration suppression, the angle of attack of the piezoelectric energy capture device based on wind-induced vibration is adjusted to a value less than zero.

[0057] Specifically, the piezoelectric energy capture device based on wind-induced vibration was verified through numerical simulation and wind tunnel tests. Analysis showed that when the double-wing attack angle α is less than 0, the vibration of the cantilever beam with a double-wing blunt body attached to the free end is suppressed. This feature can be used to avoid structural fatigue or even damage caused by adverse strong winds in nature, thereby improving the reliability and safety of the energy capture device.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for capturing piezoelectric energy from wind-induced vibrations, characterized in that: Applied to a piezoelectric energy capture device based on wind-induced vibration, the capture method includes: When it is determined based on local seasonal climate characteristics and ambient wind field data that the current wind speed is within a suitable wind speed range for vortex-induced vibration, adjusting the angle of attack of the piezoelectric energy capture device based on wind-induced vibration to a value greater than a critical value; When it is determined based on local seasonal climate characteristics and ambient wind field data that the current wind speed is within a suitable range for galloping wind speeds, adjusting the angle of attack of the piezoelectric energy capture device based on wind-induced vibration to a range between zero and a critical value; The piezoelectric energy capture device based on wind-induced vibration comprises: a first airfoil and a second airfoil; and a connecting member, wherein the first airfoil and the second airfoil are respectively rotatably arranged at two ends of the connecting member and respectively form an angle with the connecting member; a cantilever beam fixedly disposed on the connecting member; A piezoelectric sheet is fixedly arranged on the cantilever beam.

2. The piezoelectric energy capture method of wind-induced vibration according to claim 1, characterized in that: The first airfoil and the second airfoil are arranged in mirror symmetry along the central axis of the connecting member.

3. The piezoelectric energy capture method of wind-induced vibration according to claim 1, characterized in that: The first and second airfoils are provided with shaft grooves at their chord-wise and span-wise center positions, with positioning holes provided at both ends of the shaft grooves; bearings corresponding to the positioning holes are provided at both ends of the connecting member, and the bearings rotate frictionally in the positioning holes.

4. The piezoelectric energy capture method of wind-induced vibration according to claim 3, characterized in that: An elastic member is provided in the positioning hole, and the bearing is connected to the positioning hole through the elastic member.

5. The piezoelectric energy capture method of wind-induced vibration according to claim 2, characterized in that: A connecting hole is provided on one side of the connecting piece, and the cantilever beam is fixedly arranged on the connecting hole.

6. The piezoelectric energy capture method of wind-induced vibration according to claim 1, characterized in that: Before the step of adjusting the angle of attack of the piezoelectric energy capture device based on wind-induced vibration to a value greater than a critical value after determining that the current wind speed is within a suitable wind speed range for vortex-induced vibration based on local seasonal climate characteristics and ambient wind field data, the capture method further includes: The critical value is determined based on the piezoelectric energy harvesting device.

7. The piezoelectric energy capture method of wind-induced vibration according to claim 6, characterized in that: The capture method further comprises: When it is determined based on local seasonal climate characteristics and ambient wind field data that the current wind speed is in a wind speed range suitable for vibration suppression, the angle of attack of the piezoelectric energy capture device based on wind-induced vibration is adjusted to a value less than zero.

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