A Blunt Body Non-rotating Flow-induced Vibration Energy Harvesting Device

Abstract

The present invention relates to a flow-induced vibration energy collection device, specifically a bluff body non-rotating flow-induced vibration energy collection device. In terms of bluff body design, the present invention does not adopt the common design method of rigidly fixing the bluff body to an elastic beam, but adopts a rotating shaft and a connecting shaft to connect the bluff body to the elastic beam. Because the kinematic pair at the connection is a rotating pair, the bluff body will only vibrate laterally without rotating, thereby achieving the effect of increasing the amplitude at the same frequency, and finally achieving an increase in the converted electrical energy and improving the conversion efficiency.

Description

Technical Field

[0001] The invention relates to a flow-induced vibration energy collection device, in particular to a blunt-body non-rotating flow-induced vibration energy collection device, which is mainly used for maximizing the conversion of vibration energy into electrical energy and collecting it. Background Art

[0002] In recent years, due to environmental problems and the non-renewable use of fossil energy, renewable energy collection technology has received widespread attention. In the past two decades, wireless sensor networks have been widely used in various fields, and a self-powered wireless sensor network technology has been developed. Energy recycling has become a scientific problem of great significance worldwide. At the same time, energy harvesting has become an emerging technology that can convert waste energy in the environment into electrical energy. It has unlimited application prospects in the field of self-powered design of microelectronic devices and has received widespread attention from researchers at home and abroad.

[0003] Wind energy is a common energy source, and wind turbines are a typical energy conversion device that can be used to achieve the conversion of wind energy into electrical energy. At present, after using the wind-induced effect to convert wind energy into vibration energy, due to the advantages of simple structure, high output voltage and high power density of the piezoelectric effect, most of them are converted into electrical energy by the piezoelectric effect, becoming the main choice for vibration energy collection. However, wind turbines will produce strong noise during operation and have a greater dependence on strong winds. The above shortcomings limit their operation in areas with high population density. Therefore, in urban environments, a small but independent power supply is essential, so appropriate and feasible solutions are needed for self-powered sensor nodes and monitoring equipment.

[0004] In order to reduce the dependence of wireless sensors on traditional battery power supply, energy harvesting devices based on piezoelectric, electromagnetic, electrostatic, triboelectric and dielectric elastomers are developing rapidly. As an alternative to traditional turbines, flow-induced vibration energy harvesting devices can also convert low-speed wind energy in the environment into electrical energy. According to the mechanism of fluid-solid coupling, they can be divided into flutter, vortex-induced vibration, galloping and wake galloping. Due to the convenience of implementation, energy harvesting devices based on vortex-induced vibration and galloping have been widely studied. Their structural designs all utilize the unstable fluid-solid coupling between the flow field and the blunt body. However, the energy efficiency of existing energy harvesting devices under the same blunt body is not high. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a blunt body non-rotating flow-induced vibration energy capture device that can absorb wind-induced vibration energy in the external environment and convert it into electrical energy. With the continuous improvement of production technology, the power of small electronic components continues to decrease. The device of the present invention can power low-energy consumption devices such as wireless sensor nodes and detection equipment, avoiding the disadvantages of traditional battery power supply.

[0006] To achieve the above objectives, the present invention does not adopt the common design method of rigidly connecting the bluff body to the elastic beam in the design of the bluff body, but instead adopts a method of connecting the bluff body to the elastic beam through a rotating shaft and a connecting shaft. Since the kinematic pair at the connection is a rotating pair, the bluff body will only vibrate laterally without rotating, thereby achieving the effect of increasing the amplitude at the same frequency, ultimately increasing the converted electrical energy and improving the conversion efficiency.

[0007] A blunt body non-rotating flow-induced vibration energy capture device, characterized in that the energy capture device comprises a blunt body, a rotating shaft, a connecting shaft, an elastic beam, a piezoelectric film, a mounting block, a fixing frame, a slide rail, a slider, and a fastening device.

[0008] The blunt body is in the shape of a thin-walled rectangular parallelepiped as a whole, with the upper and lower ends not closed, and a rectangular parallelepiped groove is reserved on each of the two edges connected to the elastic beam. Each rectangular parallelepiped groove has a square solid body on the upper and lower end faces, and the upper and lower square solid bodies have a through hole and a blind hole respectively for placing the rotating shaft, and the through hole and the blind hole are matched with the rotating shaft clearance, so there will be no shaking.

[0009] The rotating shaft is in the shape of an elongated cylinder, and the rotating shaft and the center hole of the connecting shaft are also clearance-fitted.

[0010] One side of the connecting shaft is protruded with a central hole for connecting with the rotating shaft, and the other side is a rectangular sheet body, which is connected with the elastic beam by using an adhesive.

[0011] There are two elastic beams made of titanium alloy, which have great elastic force and restoring force, and are cantilever beams. Each elastic beam is placed between the L-shaped fixing frame and the two mounting holes of the mounting block and is fastened by bolts.

[0012] The piezoelectric film uses epoxy resin, and the piezoelectric film is attached to the root of the elastic beam to obtain higher energy conversion efficiency, because the stress and deformation at the fixed end of the elastic beam are the largest.

[0013] The mounting block is rectangular as a whole, and there are two of them. Each of the mounting blocks includes two mounting holes, and the two mounting holes are consistent in shape and size with the two mounting holes on the upper end of the fixing frame.

[0014] The fixing frame is L-shaped as a whole, with two pieces in total. Each piece has four positioning holes at the lower end. The positioning holes are consistent in shape and size with the positioning holes on the upper surface of the slider and are used to connect with the slider. There are two mounting holes at the upper end of the fixing frame for connecting with the mounting block.

[0015] The slide rail is in the shape of a rectangular block as a whole, with two rotatable slender shafts on the two inner side surfaces and two countersunk holes at the bottom for connecting with the bottom of the wind tunnel.

[0016] The slider is T-shaped as a whole, with two pieces in total. Each piece has four positioning holes on the upper surface for connecting to the L-shaped fixing frame. There are three rotating bearings arranged at equal intervals at the symmetrical center of the lower end of the slider for cooperating with the slender shaft of the slide rail to achieve smooth movement of the slider on the slide rail.

[0017] The fastening device consists of a handle, a spring, and a stopper. One end of the external handle is connected to the spring, and the other end of the spring is connected to the stopper. The spring and the stopper of the fastening device are placed as a whole in the groove at the lower end of the slider. When the two sliders are adjusted to a suitable spacing, the handle is rotated clockwise to squeeze the spring and drive the stopper to move axially to approach the inner wall of the slide rail until it contacts the inner wall, indicating that the tightening is completed and the position of the slider is fixed.

[0018] The beneficial effects of the present invention are:

[0019] The present invention provides a blunt body non-rotating flow-induced vibration energy capture device. It has the following beneficial effects:

[0020] The blunt body non-rotating flow-induced vibration energy harvesting device has a simple structure. The main parts such as the blunt body and the connecting shaft are made by 3D printing technology. Therefore, it is light in weight and can avoid unnecessary energy loss in the wind tunnel. In the previous common design, the blunt body will swing left and right with the elastic beam, and an angle will be generated relative to the axis. When the angles on both sides are different, the pressure caused will be different. It will continue to swing until the pressure on both sides of the blunt body is balanced, and then swing in the opposite direction, repeating the cycle. The blunt body design of this device is different in that there are two elastic beams and the blunt body and the elastic beam can rotate relative to each other. Therefore, when the elastic beam swings, the motion structure between the blunt body and the elastic beam can be simplified to a parallelogram. The blunt body will only vibrate laterally relative to each other, and no angle will be generated relative to the axis. The wind force will act more effectively on the front face of the blunt body, which is equivalent to increasing the amplitude at the same frequency, thereby increasing the energy collected and the power density. In this regard, we have verified it in the experiment. By comparing the amplitude changes of the ordinary rotation-translation coupling blunt body energy harvesting device and the blunt body non-rotating flow-induced vibration energy harvesting device of the present invention at different wind speeds, this conclusion can also be drawn. For comparison of experimental data, see Figure 5 .

[0021] This device can make up for the defects of the existing vibration energy collection technology, such as the energy collection device can only vibrate along the same trajectory as the fixed parts, the vibration amplitude that can be collected is low, and the energy collection efficiency is low; the present invention can be applied in a wide range of occasions, and even if there are multi-directional and multi-frequency vibrations in the working environment, the vibration energy in the working environment can be effectively collected. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a three-dimensional structural schematic diagram of the blunt body non-rotational flow-induced vibration energy harvesting device described in the present invention, and the numbers of the corresponding component structures have been marked.

[0023] Figure 2 Schematic diagram of the internal structure of the bluff body of the present invention, with the numbers of the corresponding components marked.

[0024] Figure 3 It is a schematic diagram of the matching structure of the connecting shaft and the rotating shaft of the present invention, and the numbers of the corresponding component structures have been marked.

[0025] Figure 4 It is a schematic diagram of the working principle of the blunt body non-rotating flow-induced vibration energy harvesting device described in the present invention, and the numbers of the corresponding component structures have been marked.

[0026] Figure 5 This is a comparison chart of experimental data, and the model corresponding to the curve has been marked.

[0027] Figure 6 It is an output circuit diagram of the blunt body non-rotational flow-induced vibration energy capture device described in the present invention.

[0028] In the figure: 1-slide rail; 2-slider; 3-fixed frame; 4-mounting block; 5-elastic beam; 6-piezoelectric film; 7-blunt body; 8-connecting shaft; 9-rotating shaft; 10-fastening device. DETAILED DESCRIPTION

[0029] In order to fully understand the purpose, features and effects of the present invention, the present invention is described in detail through the following specific implementation methods.

[0030] like Figure 1 , 2 As shown in Figures 3 and 4, the blunt body non-rotating flow-induced vibration energy capture device of the present invention comprises a slide rail 1, a slider 2, a fixing frame 3, a mounting block 4, an elastic beam 5, a piezoelectric film 6, a blunt body 7, a connecting shaft 8, a rotating shaft 9, and a fastening device 10; the slide rail 1 is the bottommost component of the energy capture device of the present invention, and the lower end of the slide rail 1 is fixedly matched with the wind tunnel box, and the slider 2 on the slide rail 1 is connected to the fixing frame 3 for adjusting the spacing, and the spatial position of the blunt body 7 in the wind tunnel box can be changed by adjusting the relative position of the fixing frame 3 and the slide rail 1, so as to keep the blunt body 7 at the center position of the wind tunnel cross section and reduce the adverse effects of turbulence on the experiment; the elastic beam 5 is located between the two holes of the mounting block 4 and fixed between the fixing frame 3 and the mounting block 4, and the piezoelectric film 6 is attached to the root of the exposed fixed end of the elastic beam 5. Since the deformation of the root is the largest, the highest energy conversion efficiency can be obtained. In addition, the free end of the elastic beam 5 is bonded to the connecting shaft 8.

[0031] like Figure 2 , as shown in FIG. 3 , the bluff body 7 is the rightmost component of the energy capture device of the present invention, and the wind force directly acts on the end surface of the bluff body 7. In addition, the rotating shaft 9 passes through the connecting shaft 8 and is placed in the rectangular parallelepiped groove of the bluff body 7, and can rotate freely;

[0032] like Figure 4 As shown, the working principle of the energy capture device is that the bluff body 7 and the elastic beam 5 can rotate relative to each other, so that when the wind force acts on the bluff body, the bluff body will only vibrate laterally, thereby achieving the experimental purpose.

[0033] Working process

[0034] The wind tunnel starts to work after being powered on. The airflow is sucked in from the wind tunnel inlet and acts on the front face of the bluff body 7. The bluff body 7 is subjected to force, which drives the elastic beam 5 to bend. The wind-induced effect converts wind energy into vibration energy. Since the bluff body 7 and the elastic beam 5 can rotate relative to each other, the bluff body 7 vibrates laterally and the elastic beam swings left and right with equal amplitude. The piezoelectric film 6 at the root of the elastic beam 5 is subjected to pressure and converted into electrical energy by the piezoelectric effect. The piezoelectric film 6 is connected to an external circuit, and the output voltage signal is measured and processed by a data acquisition instrument, and is connected to a PC for data monitoring and processing. Low-power electrical appliances can be connected to the external circuit to make full use of the converted electrical energy. In addition, the wind tunnel box is made of a transparent acrylic plate, and a laser displacement sensor is installed on its side. An anemometer is installed above the wind tunnel box to measure the instantaneous upstream wind speed. They cooperate with each other to adjust the different variable values ​​required for the experiment in real time. The overall circuit diagram is as follows Figure 6 shown.

[0035] The specific implementation methods described above have described in detail the technical solutions and beneficial effects of the present invention. It should be understood that the above is only the most preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A blunt body non-rotating flow-induced vibration energy capture device, characterized in that: The energy capture device includes a blunt body, a rotating shaft, a connecting shaft, an elastic beam, a piezoelectric film, a mounting block, a fixing frame, a slide rail, a slider, and a fastening device; The bluff body is a thin-walled cuboid as a whole, with the upper and lower ends not closed, and a cuboid groove is left on each of the two edges connected to the elastic beam, and each of the upper and lower end faces of each cuboid groove has a square entity, and the upper and lower square entities have a through hole and a blind hole respectively for placing the rotating shaft; One side of the connecting shaft is convex with a central hole for connecting with the rotating shaft, and the other side is a rectangular sheet body, which is connected to the elastic beam by an adhesive; There are two elastic beams in total, which are cantilever beams. Each elastic beam is placed between the two mounting holes of the L-shaped fixing frame and the mounting block and is fastened by bolts. The piezoelectric film is attached to the root of the elastic beam to obtain a higher energy conversion efficiency; The mounting block is rectangular as a whole, and there are two of them, each of which includes two mounting holes, and the two mounting holes are consistent in shape and size with the two mounting holes on the upper end of the fixing frame; The fixing frame is L-shaped as a whole, with two pieces in total, and each piece has four positioning holes at the lower end, which are consistent in shape and size with the positioning holes on the upper surface of the slider, and are used to connect with the slider. The upper end of the fixing frame has two mounting holes for connecting with the mounting block; The slide rail is in the shape of a rectangular block as a whole, with two rotatable slender shafts on the two inner side surfaces and two countersunk holes at the bottom for connecting with the bottom of the wind tunnel; The slider is T-shaped as a whole, with two pieces in total. Each piece has four positioning holes on its upper surface for connecting with the L-shaped fixing frame. Three rotating bearings are arranged at equal intervals at the symmetrical center of the lower end of the slider for cooperating with the slender shaft of the slide rail to achieve smooth movement of the slider on the slide rail. The fastening device is used to fix the position of the slider, and the fastening device consists of a handle, a spring, and a stopper. One end of the external handle is connected to the spring, and one end of the spring is connected to the stopper. The spring and the stopper of the fastening device are placed as a whole in the groove at the lower end of the slider. When the two sliders are adjusted to a suitable spacing, the handle is turned clockwise to squeeze the spring to drive the stopper to move axially to approach the inner wall of the slide rail until it contacts the inner wall, indicating that the tightening is completed and the position of the slider is fixed.

2. A blunt body non-rotating flow-induced vibration energy harvesting device as claimed in claim 1, characterized in that: The through hole and the blind hole are matched with the rotating shaft clearance, and no shaking will occur.

3. A blunt body non-rotating flow-induced vibration energy harvesting device as claimed in claim 1, characterized in that: The rotating shaft is in the shape of an elongated cylinder, and the rotating shaft and the center hole of the connecting shaft are also clearance-fitted.

4. A blunt body non-rotating flow-induced vibration energy harvesting device as claimed in claim 1, characterized in that: The elastic beam is made of titanium alloy.

5. A blunt body non-rotating flow-induced vibration energy harvesting device as claimed in claim 1, characterized in that: The piezoelectric film uses epoxy resin.

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