This application claims priority to Korean Patent Application Nos. 10-2023-0165698 (filed on Nov. 24, 2023) and 10-2024-0027111 (filed on Feb. 26, 2024), which are all hereby incorporated by reference in their entirety.
The present invention relates to a wind Energy Harvester, more specifically to a bladeless wind energy generator capable of converting the strong vortex-induced vibrations of the bluff body, produced by the fluid-structure interaction between wind and bluff body, to continuous rotary motion through mechanical rectification. To do so the downstream vortices are intensified through merging of added obstacle vortices.
Generally, a wind turbine is a device that converts wind energy into electric energy using the rotational forces generated from blades rotating. For example, a conventional wind turbine having a blade orientation angle-adjuster is disclosed in Korean Patent No. 10-0960042 (May 31, 2010).
In the case of the conventional wind turbine, however, a low energy generation efficiency of about 40 to 45% is made, and disadvantageously, a lot of time and costs in manufacturing, delivering, installing, and repairing the wind turbine are needed.
Korean Patent No. 10-0960042 (May 31, 2010)
Accordingly, the present invention has been made given the problems mentioned above occurring in the related art, and it is an object of the present invention to provide a bladeless wind energy harvester that is capable of using the strong vortex-induced vibrations generated by downstream vortices that are intensified through the merging of obstacle vortices. Oscillations the bluff body, which performs the role of an inverted pendulum, prepares the continuous rotation of the generator, and consequently, the wind energy will convert into electric energy.
The technical problems to be achieved through the present invention are not limited as mentioned above, and other technical problems not mentioned herein will be obviously understood by one of ordinary skill in the art through the following description.
To accomplish the above-mentioned objects of the present invention, a bladeless wind energy harvester according to an embodiment of the present invention may include: a bluff body; an obstacle spaced apart from the bluff body and having a longer plane section than the bluff body; a gear box located below the bluff body to rotatably support the bluff body and transferring the rotation of the bluff body; and a generator connected to the gear box and mechanical rectifier by means of a shaft, wherein the bluff body and the obstacle are parallel to each other so that the bluff body rotates by means of vortices generated from the interaction between wind and the obstacle to allow the generator to generate electric energy.
According to the embodiment of the present invention, further, the gear box may include a mechanical rectifier adapted to convert the reciprocal rotations of the shaft into a unidirectional rotation.
According to the embodiment of the present invention, the wind turbine may further include a distance adjuster coupled to the obstacle and transferring the obstacle to adjust a distance between the bluff body and the obstacle.
According to the embodiment of the present invention, the wind turbine may further include a plate supporting the gear box and the obstacle in such a way as to be rotatable around a shaft vertical to the surface of the ground.
According to the embodiment of the present invention, the wind energy generator includes a flow guide attached to the foundation plate that holds the bluff body and the obstacle in such a way as to have a plane section in a vertical direction to the obstacle, wherein if the wind blows different with the flow guide direction, the foundation plate rotates to allow the obstacle to be placed in a direction toward the wind.
According to the embodiment of the present invention, the bladeless wind energy harvester is capable to use the vortex induced vibrations generated upon interaction between wind and the bluff body to rotate the generator and convert wind energy into electric energy.
That is, the main principle of the bladeless wind energy generator according to the present invention makes use of vibrations produced from the vortices generated when wind blows across the wind energy generator to convert wind energy into electric energy. The conventional wind turbine having blades has power generation efficiency of 40 to 45%, but the bladeless wind turbine according to the present invention has power generation efficiency of about 60% or more. Further, the bladeless wind turbine according to the present invention is reduced in manufacturing, delivering, installing, and repairing costs, and as rotations of blades do not exist, the bladeless wind energy harvester according to the present invention is provided with parts that do not require a lot of motions, so that the time and cost for the maintenance of the parts are reduced. Furthermore, the bladeless wind energy harvester according to the present invention has no blade with rotary motion, thereby allowing humans and animals to live safely near it, it generates lower acoustic noise, all mechanical and electrical parts are close to the ground and it can easily be maintained, and it can be located on regions relatively close to cities or energy consumption districts.
The effectiveness of the invention is not limited as mentioned above, and it should be understood to those skilled in the art that the effectiveness of the invention may include another effectiveness as not mentioned above from the detailed description of the present invention.
Terms used in the specification will be explained briefly, and an embodiment of the present invention will be explained in detail.
All terms as will be discussed later are defined in accordance with the functions of the present invention, but may be varied under the intention or regulation of a user or operator. Therefore, they should be defined on the basis of the whole scope of the present invention.
In the description, when it is said that one portion is described as “includes” any component, one element further may include other components unless no specific description is suggested.
Hereinafter, the embodiment of the present invention will be explained in detail with reference to the attached drawings to be easily understood by those of ordinary skill in the art. However, the present invention may be freely modified within the scope of the invention, without being limited to the embodiment as will be discussed later.
Technical problems and solutions of the present invention and the effectiveness of the present invention will be included in the detailed description as will be described below and the attached drawings. Objects, characteristics and advantages of the present invention will be more clearly understood from the detailed description as will be described below and the attached drawings.
Flow-induced vibration (FIV) is a physical phenomenon widely observed in an engineering field, which is generated by aerodynamic instability or vortex shedding when a fluid blows across a thin structure. That is, a wind turbine of the present invention is an FIV energy harvesting device that extracts (harvests) energy from a flow field therearound and thus provides power. While a fluid is flowing along a bluff body, a vortex distance or Karman vortex distance is generated from a vortex region. Periodical vortex shedding from the surface of the bluff body applies asymmetrical pressure to the structure and thus produces alternating aerodynamic forces. Such alternating aerodynamic forces cause the vibrations of the bluff body, and the vibrations are used to produce power.
Hereinafter, an embodiment of the present invention will be described in detail with referent to the attached drawings.
Referring to
First, the bluff body 100 is provided. The bluff body 100 is a massive object that rotates by means of the vortices generated from the interaction between wind and the obstacle 300 and thus transmits wind energy in the form of a pendulum motion. For example, referring to
Next, the gear box 200 is provided. The gear box 200 transfers the rotation of the bluff body 100 generated by the vortices of wind to the generator 400 in the form of a rotational motion. For example, referring to
Further, the gear box 200 includes the mechanical rectifier 250 adapted to convert the rotation of the shaft into unidirectional rotation. That is, while the mechanical rectifier 250 is receiving the pendulum motion of the bluff body 100, it converts rotations of one direction and the other direction into the unidirectional rotation and transfers the converted rotation to the generator 400. In detail, the mechanical rectifier 250 converts a clockwise rotation and a counterclockwise rotation into the unidirectional rotation to allow the shaft connecting the gear box 200 and the generator 400 to rotate unidirectionally.
In more detail, if the mechanical rectifier 250 is not provided, the shaft performs a reciprocal rotation, not a unidirectional rotation, as the partial gear 130 moves. That is, if the partial gear 130 rotates in a clockwise direction, the first transmission gear 220 and the second transmission gear 230 rotate in counterclockwise directions to allow the shaft to rotate in the counterclockwise direction, and if the partial gear 130 is returned to its original position or rotates in the counterclockwise direction, the first transmission gear 220 and the second transmission gear 230 rotate in the clockwise directions to allow the shaft to rotate in the clockwise direction. That is, the mechanical rectifier 250 converts the reciprocal rotation into the unidirectional rotation to allow the rotation in a given direction to be transferred to the generator 400. In this case, the mechanical rectifier 250 may further include a planetary gear (not shown) adapted to increase a rotational speed.
For example, referring to
Accordingly, the rotational motion of the partial gear 130 is transferred to the first transmission gear 220 and then transferred to the first gear 252 through the first shaft 251. In this case, the clockwise rotational motion of the first shaft 251 rotates the first gear 252 in the clockwise direction, and also, the unidirectional clutch 254 located on the second gear 253 rotates in the clockwise direction. As the unidirectional clutch 254 closed in the clockwise direction is coupled to the second gear 253, the clockwise rotational motion of the first shaft 251 is transferred to the second gear 253. Contrarily, the counterclockwise rotational motion of the third gear 255 operating through the clockwise rotational motion of the first gear 252 is transferred to the unidirectional clutch 254 located on the fourth gear 257 through the second shaft 256. In this case, also, as the unidirectional clutch 254 located on the fourth gear 257 is closed in the clockwise direction and open in the counterclockwise direction, the counterclockwise rotational motion of the second shaft 256 is not transferred to the fourth gear 257. Accordingly, the output gear 258 rotates in the counterclockwise direction, and also, the output shaft 259 rotates in the counterclockwise direction.
Contrarily, the counterclockwise rotational motion of the first shaft 251 rotates the first gear 252 in the counterclockwise direction. As the unidirectional clutch 254 located on the second gear 253 is open in the counterclockwise direction, the counterclockwise rotational motion of the first shaft 251 is not transferred to the second gear 253. Contrarily, the third gear 255 rotates in the clockwise direction through the counterclockwise rotational motion of the first gear 252, and the clockwise rotation of the third gear 255 is transferred to the unidirectional clutch 254 located on the fourth gear 257 through the second shaft 256. In this case, also, as the unidirectional clutch 254 located on the fourth gear 257 is closed in the clockwise direction, the fourth gear 257 rotates in the clockwise direction through the clockwise rotational motion of the second shaft 256. Accordingly, the output gear 258 rotates in the counterclockwise direction through the clockwise rotation of the fourth gear 257, and also, the output shaft 259 rotates in the counterclockwise direction. As a result, the output shaft 259 rotates unidirectionally, that is, only in the counterclockwise direction, without being influenced by the rotational direction of the shaft. That is, the reciprocal rotation of the partial gear 130 through the pendulum motion of the bluff body 100 is transferred to the output shaft 259, so that as the output shaft 259 rotates only in the counterclockwise direction, the electric power can be generated consistently through the generator 400.
Next, the obstacle 300 is provided. The obstacle 300 serves to collide against wind to induce the wind to generate vortices. For example, the obstacle 300 has the shape of a plate with a longer horizontal length than a diameter of the main body 110. That is, the obstacle 300 includes a plane section portion 310 having the shape of a rectangular plate and coupling bars 320 coupled between the underside of the plane section portion 310 and a slider 510 as will be discussed later. Further, the obstacle 300 is linearly transferred by means of a distance adjuster 500 as will be discussed later, so that a distance between the obstacle 300 and the bluff body 100 can be adjusted. Furthermore, the obstacle 300 is arranged parallel to the bluff body 100 and a flow guide 700 as will be discussed later in a straight line.
Next, referring to
Next, the bladeless wind energy harvester according to the present invention further includes the plate 600 supporting the gear box 200 and the obstacle 300 in such a way as to be rotatable around a shaft vertical to the surface of the ground. For example, the plate 600 has the shape of a disc and is supported against a trust bearing 620 in such a way as to rotate by means of the flow guide 700 as will be discussed later according to the direction of the wind. That is, the plate 600 includes a plate body 610 having the shape of a disc, a support body 620 located under the plate body 610 to support the plate body 610, and the trust bearing 630 located between the plate body 610 and the support body 620 to rotate the plate body 610. In this case, a vertical rotational shaft is provided for the plate body 610, so that the plate body 610 rotates around the rotational shaft vertical to the surface of the ground.
Further, the bladeless wind energy harvester according to the present invention includes the flow guide 700 arranged side by side with the bluff body 100 and the obstacle 300 above the plate 600 in such a way as to have a plane section in a vertical direction to the obstacle 300, and if the wind collides against the flow guide 700, the plate 600 rotates to allow the obstacle 300 to be placed in a direction toward the wind. That is, the obstacle 300 and the flow guide 700 are arranged in directions vertical to each other. In detail, the plane section portion 310 of the obstacle 300 and a plane section portion 710 of the flow guide 700 are arranged vertical to each other to allow the obstacle 300 to be placed in a direction toward the wind. For example, referring to
Referring to
In this case, referring to
Further, the bladeless wind energy harvester according to the present invention obtains high power generation efficiency as vortices having high Reynolds number are generated. Accordingly, the cross-sectional shape of the bluff body 100 may be made to a shape capable of inducing the wind to have a turbulent flow.
For example, referring to ’, so that the Reynolds number of the wind colliding against the bluff body 102 increases, thereby improving power generation efficiency.
Further, referring to
Furthermore, referring to
As described above, the bladeless wind energy harvester according to the present invention is capable to use the vibrations produced by vortex induced vibration of the bluff body and consequently rotation of generator to convert wind energy into electric energy, thereby advantageously improving the energy generation efficiency.
Although the embodiments above have been described in considerable detail, numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated.
While the present invention has been described with reference to the particular illustrative embodiments, it is not to be restricted by the embodiments but only by the appended claims. It is to be appreciated that those skilled in the art can change or modify the embodiments without departing from the scope and spirit of the present invention. It is therefore intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.
According to the present invention, such new geometric shapes for the bluff body are suggested, and the obstacle behind the bluff body is also utilized, so that a distance between the obstacle and the bluff body is optimized to improve the energy generation efficiency of the FIV-based energy harvesting device. According to the present invention, the bluff body has the optimized geometric structure, and if the flat obstacle behind the bluff body is utilized, further, vibration amplitudes increase to raise the harvested energy. That is, as the Reynolds number increases, an amount of power generated increases. The optimal distance of Z/D is 0.36, and as the obstacle is used at the optimal distance, the highest amount of power generated through the geometric structure suggested when the Reynolds number=16000 is larger by 26% than the cylindrical bluff body having the obstacle. The cylindrical bluff body utilizing the obstacle has an amount of power generated larger by about 85% than that utilizing no obstacle. If the width of the obstacle is equal to the diameter of the cylindrical bluff body, the bladeless wind energy harvester has better performance. The geometric structure of the bladeless wind energy harvester with the suggested obstacle allows the largest number of vortices to be generated. In the case of a convex model with the obstacle, the highest value of turbulent flow energy is greater by 41% than a simple model, which is obtained by unstable aerodynamic force applied to the model. According to an instant flow pattern and a speed vector image, vortex shedding of the convex model with the obstacle increases the vortex shedding of the obstacle behind the model, and the vortices shed are added to produce stronger vortices. To produce manual control for wake parameters and suggest a new generation bladeless wind energy harvester, lastly, there is suggested a new configuration wherein the obstacle is located on the downstream of the bluff body providing important influences on induced voltages. The geometric shape of the bluff body, which is inspired by nature, has an optimal width, and further, the obstacle is located at an optimal distance from the bluff body, so that the bladeless wind energy harvester according to the present invention can have an amount of harvested energy of about 86% larger than the existing bladeless wind turbine.
Number | Date | Country | Kind |
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10-2023-0165698 | Nov 2023 | KR | national |
10-2024-0027111 | Feb 2024 | KR | national |