Efficient annular vertical axis wind turbine, wind turbine and wind power generation system

Abstract

The invention relates to an efficient annular vertical axis wind turbine, a wind turbine and a wind power generation system.The wind turbine comprises annular blades, a main shaft, a horizontal support and a base, the main shaft is vertically installed on the base, the annular blades are evenly arranged in the circumferential direction of the main shaft, and the horizontal support is connected with the main shaft and the annular blades; the annular blade, the main shaft and the horizontal support rotate synchronously; the annular blades are sequentially a first variable-section blade, a uniform-section blade and a second variable-section blade from top to bottom, the top of the first variable-section blade is connected with the spindle through a flange, the bottom of the second variable-section blade is connected with the spindle through a flange, the uniform-section blade is parallel to the spindle, and the uniform-section blade is connected with the spindle through a horizontal support. The variable cross-section design is adopted for the arc-shaped blades of the annular blades, the base and the main shaft of the wind turbine bear the gravity of the blades, and the wind energy utilization coefficient of the wind turbine is increased while the construction cost of the vertical axis wind turbine is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power generation, and in particular to a vertical axis wind power generation device, and specifically to a high-efficiency annular vertical axis wind wheel, a wind turbine and a wind power generation system. Background Art

[0002] Wind energy, as a widely distributed, pollution-free renewable energy source, is highly valued and has made great progress in the past decade.

[0003] For coastal islands, grassland pastoral areas, mountainous areas, plateau areas and remote rural areas with scarce water resources and inconvenient transportation, utilizing wind power generation in accordance with local conditions has far-reaching significance.

[0004] However, the development of distributed wind power in rural areas faces a series of key technical challenges. The blade tips of common horizontal-axis wind turbines have a high linear velocity during rotation, and a large number of tip vortices are generated at the tip of the blades, which not only reduces the aerodynamic performance of the wind turbine, but also generates a lot of noise. Excessive aerodynamic noise during the operation of horizontal-axis wind turbines affects the lives of residents, and the aerodynamic performance of wind turbines is poor in low wind speed environments. Therefore, in view of the low wind speed and high turbulence environment conditions of distributed wind farms in rural areas, it is necessary to develop a new type of wind turbine with higher wind power generation efficiency and lower noise pollution.

[0005] Compared with the large number of horizontal axis wind turbines on the market, vertical axis wind turbines have the advantages of simple structure, flexible installation, convenient maintenance, small footprint, safety and stability, low accident rate and low operating noise. They can improve the efficiency of wind energy utilization in low wind speed areas. At the same time, their high efficiency can also meet the requirements of developing wind power generation in densely populated areas. Therefore, vertical axis wind turbines are particularly suitable for distributed wind power development. The application of vertical axis wind turbines is earlier than that of horizontal axis wind turbines. Darrieus type wind turbines have appeared and been put into use as early as the 1930s. Since the 1970s, Sandia Laboratory in the United States has conducted a series of field tests on Darrieus type vertical wind turbines. At the same time, a batch of commercial vertical axis wind turbines installed have also provided valuable data support for related research; the Dabiri team of the California Institute of Technology in the United States has also carried out a series of field studies on vertical axis wind turbines. The research content mainly focuses on the mutual influence between vertical axis wind turbines and their impact on the overall power generation efficiency of wind farms. Through testing, it is verified that there is an aerodynamic gain effect between vertical axis wind turbines, which can significantly improve the power generation performance of wind turbines. In addition, compared with horizontal axis wind turbines, the wake recovery speed of vertical axis wind turbines is faster, which means that more wind turbines can be arranged in the same area. In summary, vertical axis wind turbines are the best choice for distributed wind farms in rural areas.

[0006] Vertical axis wind turbines can be divided into resistance type vertical axis wind turbines and lift type vertical axis wind turbines according to their working principles. The wind energy utilization coefficient of the resistance type vertical axis wind turbine is relatively low, generally not exceeding 0.3. The wind energy utilization coefficient of the lift type vertical axis wind turbine is relatively high, but there are still some problems. Common lift type vertical axis wind turbines are divided into Darrieus type vertical axis wind turbines and H type vertical axis wind turbines. The blades of the Darrieus type vertical axis wind turbine are elliptical. Although its wind energy utilization coefficient is relatively high, its effective swept area is relatively small, resulting in a relatively small power generation of a single machine. The H type vertical axis wind turbine has a relatively large swept area and a higher overall power generation, but its straight blades will generate tip vortices at both ends, which seriously reduces the aerodynamic performance of both ends of the blades, resulting in a low wind energy utilization coefficient of the H type vertical axis wind turbine. In addition, the H type vertical axis wind turbine connects the main shaft and the blades through a cross brace, which not only makes the weight of the blades only rely on the cross brace, increases the construction cost of the cross brace, but also greatly reduces the aerodynamic performance of the blades.

[0007] The existing vertical axis wind turbines all have their own shortcomings, which also makes them unable to meet the use standards of rural areas and science and technology parks. Therefore, there is an urgent need to design an efficient vertical axis wind turbine with a higher wind energy utilization coefficient and capable of operating well in low wind speed and high turbulence environments, so as to provide a new solution for improving the wind energy utilization coefficient of vertical axis wind turbines and realizing the large-scale vertical axis wind turbines. At the same time, unlike the horizontal axis wind turbine, the present invention adopts annular blades, and there is no tip of the blade, which can prevent the generation of tip vortices. In addition, the rated speed of the present invention is relatively small during operation, and the smaller speed also makes the noise generated by the present invention during operation smaller. Moreover, the present invention adopts annular blades, and uses the arc blades at both ends of the blades to bear the weight of the blades, reducing the load of the cross braces, which can effectively reduce the number and size of the cross braces, while saving the construction cost of the vertical axis wind turbine and improving the wind energy utilization coefficient of the wind turbine. Summary of the invention

[0008] In view of the shortcomings of the prior art, the present invention provides a highly efficient annular vertical axis wind wheel, a wind turbine and a wind power generation system. The present invention adopts annular blades, uses the arc blades at both ends of the blades to bear the weight of the blades, reduces the load of the cross braces, can effectively reduce the number of cross braces and the size of the cross braces, and improves the wind energy utilization coefficient of the wind turbine while saving the construction cost of the vertical axis wind turbine.

[0009] The technical means adopted by the present invention are as follows:

[0010] A high-efficiency annular vertical axis wind turbine, comprising: annular blades, a main shaft, a horizontal support and a base, wherein the main shaft is vertically mounted on the base, a plurality of annular blades are evenly arranged along the circumference of the main shaft, the horizontal support is used to connect the main shaft and the annular blades, and the annular blades, the main shaft and the horizontal support rotate synchronously;

[0011] The annular blades are, from top to bottom, a first variable-section blade, a constant-section blade, and a second variable-section blade. The top of the first variable-section blade is connected to the main shaft via a flange, the bottom of the second variable-section blade is connected to the main shaft via a flange, the constant-section blade is arranged parallel to the main shaft, and the constant-section blade is connected to the main shaft via a horizontal support.

[0012] Furthermore, the horizontal support is a cross brace, which is made of glass fiber composite material and is used to connect the main shaft and blades of equal cross-section to improve the structural stability of the wind wheel.

[0013] Furthermore, the horizontal support is a sling, which is a steel cable. Lifting rings are provided on the flanges of the blades with uniform cross-sections and the main shaft, and both ends of the sling are connected to the lifting rings to achieve the connection between the main shaft and the blades with uniform cross-sections.

[0014] Furthermore, the chord length of the first variable-section blade gradually decreases as the radius of the wind rotor increases, and for every 10% increase in the blade height, the chord length is 1.0 to 1.2 times the previous chord length; the chord length of the second variable-section blade gradually increases as the radius of the wind rotor decreases, and for every 10% decrease in the blade height, the chord length is 1.0 to 1.2 times the previous chord length; the ratio of the width to the chord length of the first variable-section blade and the second variable-section blade is 0.12 to 0.25.

[0015] Furthermore, the blade chord length and width of the uniform cross-section vertical blade remain constant from top to bottom, and the ratio of the chord length to the wind wheel radius is less than 0.25, and the ratio of the uniform cross-section blade width to the chord length is 1.0 to 3.0.

[0016] Furthermore, the chord length is the distance between two end points of the blade on the same horizontal line, and the wind wheel radius is the vertical distance from the main axis to the line connecting the two end points of the blade on the same horizontal line.

[0017] Furthermore, metal structural parts are embedded in the first variable-section blade, the uniform-section blade, the second variable-section blade and both ends of the cross brace to enhance structural strength, connect flanges and install steel cables.

[0018] Furthermore, the main shaft includes a connecting shaft and a transmission shaft, the upper end of the transmission shaft is connected to the lower end of the connecting shaft through an axis end flange, the lower end of the connecting shaft is connected to the end of the second variable-section blade, the upper end of the connecting shaft is connected to the top of the first variable-section blade, and the middle part of the connecting shaft is connected to the equal-section blade through a horizontal support.

[0019] Furthermore, bearings are arranged at both ends of the transmission shaft, and the connection between the upper end of the transmission shaft and the lower end of the connecting shaft transmits the gravity of the upper end component to the rotating base through the bearing, and the bearing resists the rotational torque generated when the wind wheel rotates.

[0020] Furthermore, the uniform cross-section blades are connected to the main shaft via horizontal supports, and the horizontal supports arranged at the same level are all located on the same horizontal line, the first variable cross-section blades are connected to the uniform cross-section blades via flanges, the second variable cross-section blades are connected to the uniform cross-section blades via flanges, and a horizontal support is provided at the connection to connect to the main shaft to strengthen the structure of the connection.

[0021] Furthermore, the cross brace is connected to the blades with equal cross-sections via a flange, and the cross brace is connected to the main shaft via a flange.

[0022] Furthermore, the uniform cross-section blades are connected to the main shaft by a plurality of steel cables, and the steel cables are connected to the main shaft and the uniform cross-section blades by lifting rings. According to the structural strength requirements of the wind turbine, each lifting ring is connected to 1 to 2 steel cables; when the number of annular blades evenly arranged circumferentially of the main shaft is greater than 3, the uniform cross-section blades are connected by steel cables.

[0023] A high-efficiency annular vertical axis wind turbine comprises a generator and the high-efficiency annular vertical axis wind wheel, wherein the generator is located between the transmission shaft and a base.

[0024] Furthermore, the transmission shaft is connected to the generator rotor through a coupling; when working, the annular blades, the main shaft and the horizontal support serve as the rotor, and the generator casing serves as the stator to generate electricity.

[0025] A wind power generation system comprises a plurality of the above-mentioned high-efficiency annular vertical axis wind turbines, each of which is connected to a grid.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] The present invention discloses a high-efficiency annular vertical axis wind wheel, which has a large wind sweeping area, a high wind energy utilization coefficient, and a high single-machine power generation. When the height and diameter are consistent, the wind energy utilization coefficient of the annular vertical axis wind turbine using the high-efficiency annular vertical axis wind wheel of the present invention is increased by 35% compared with the H-type vertical axis wind turbine, wherein the wind energy utilization coefficient of the straight blade part is increased by 45%, and the wind energy utilization coefficient of the arc blade part is increased by 25%. As the height increases, the length of the straight blades of the annular vertical axis wind turbine also increases, and the percentage of the wind energy utilization coefficient of the annular vertical axis wind turbine also increases.

[0028] At the same time, the curved blades adopt a variable cross-section design. The gravity of the blades is transmitted to the main shaft through the curved blades at the upper and lower ends. The main shaft bears the gravity of the blades, so that the horizontal cross brace only needs to bear the centrifugal force of the blades. The use of steel cables further reduces the load of the horizontal cross brace, making it possible to design it lightweight, reduce the construction cost of the horizontal cross brace, and reduce the resistance generated by the horizontal cross brace when the wind turbine rotates at high speed, further improving the wind energy utilization coefficient of the annular vertical axis wind turbine.

[0029] In addition, as the distance between the curved blade and the main axis decreases, the chord length and width of the blade increase synchronously, which not only improves the aerodynamic performance of the blade and increases the power generation efficiency of the wind turbine, but also increases the structural strength of the curved blade, allowing the large-scale blade to bear its own gravity.

[0030] Based on the above reasons, the present invention can be widely promoted in the technical field of wind power generation and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0032] Figure 1 It is an oblique view of a high-efficiency annular vertical-axis wind wheel of the present invention.

[0033] Figure 2 It is a partial view of the middle part of the main shaft of a high-efficiency annular vertical axis wind wheel of the present invention.

[0034] Figure 3 It is a partial view of the connection between the variable-section blades and the uniform-section blades of a high-efficiency annular vertical-axis wind turbine of the present invention.

[0035] Figure 4 It is a partial view of the top of the main shaft of a high-efficiency annular vertical axis wind wheel of the present invention.

[0036] Figure 5 It is a partial view of the main shaft bottom of a high-efficiency annular vertical axis wind wheel of the present invention.

[0037] Figure 6 It is a partial view of a power generation mechanism of a high-efficiency annular vertical axis wind wheel of the present invention.

[0038] Figure 7 It is a schematic diagram of a pre-embedded metal structural part inside a high-efficiency annular vertical axis wind turbine blade of the present invention.

[0039] Figure 8It is a schematic diagram of the chord length of blades and the radius of the wind wheel of a high-efficiency annular vertical axis wind turbine of the present invention.

[0040] Fig. 9 It is a structural schematic diagram of a small-sized high-efficiency annular vertical axis wind turbine according to the present invention.

[0041] In the figure: 1a, top flange; 1b, bottom flange; 2a, first variable-section blade; 2b, equal-section blade; 2c, second variable-section blade; 3a, connecting shaft; 3b, transmission shaft; 4, cross brace; 5, steel cable; 6, generator; 7, base; 8, main shaft connecting flange; 9, cross brace-blade connecting flange; 10, blade connecting flange; 11a, top connecting flange; 11b, bottom connecting flange; 12a, upper end flange; 12b, lower end flange; 13, transmission shaft sleeve; 14, bolt connection pair; 15, tapered roller bearing; 16, sleeve bottom end cover; 17, double-through stud; 18, double diaphragm coupling; 19, embedded metal rod; 20, embedded metal plate. DETAILED DESCRIPTION

[0042] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0043] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0044] Example 1

[0045] like Figure 1 As shown, the present invention provides a high-efficiency annular vertical axis wind turbine, which mainly includes annular blades, a main shaft, a cross brace 4 and a base 7. The main shaft is vertically mounted on the base 7, and a plurality of annular blades are evenly arranged along the circumference of the main shaft. The annular blades, the main shaft and the cross brace 4 rotate synchronously. Figure 1Schematic diagram of a wind turbine with two annular blades.

[0046] The annular blades are, from top to bottom, the first variable-section blade 2a, the uniform-section blade 2b and the second variable-section blade 2c; the top of the first variable-section blade 2a is connected to the main shaft through a flange, the bottom of the second variable-section blade 2c is connected to the main shaft through a flange, the uniform-section blade 2b is arranged parallel to the main shaft, and the uniform-section blade 2b is connected to the main shaft through a cross brace 4, which is used to connect the main shaft and the uniform-section blade 2b, thereby further improving the structural stability of the wind wheel.

[0047] The chord lengths of the first variable-section blade 2a and the second variable-section blade 2c gradually decrease as the rotor radius increases. The chord length and width of the uniform-section blade 2b remain unchanged from top to bottom, and the ratio of the chord length to the rotor radius remains unchanged.

[0048] When in use, the specific dimensions of the first variable cross-section blade and the second variable cross-section blade remain consistent in the same wind turbine. The ratio of the width to the chord length of the variable cross-section blade remains unchanged, and its value remains between 0.12 and 0.25. The variable cross-section blade is divided into ten sections in proportion to the wind turbine radius, and the end of each variable cross-section blade with a larger wind turbine radius is defined as the head, and the end with a smaller wind turbine radius is defined as the tail. Then, the chord length of the tail of each variable cross-section blade is 1.0 to 1.2 times the chord length of the head of the variable cross-section blade. The height of the variable cross-section blade is related to the wind turbine radius, and its size is 0.1 to 1.0 times the wind turbine radius. In the same wind turbine, the chord length of the head of the variable cross-section blade with the largest wind turbine radius is consistent with the chord length of the equal cross-section blade, and both are less than 0.25 times the wind turbine radius. The ratio of the width to the chord length of the equal cross-section blade is consistent with that of the variable cross-section blade. Its height is related to the wind turbine radius and is 1.0 to 3.0 times the wind turbine radius.

[0049] Specifically, at different heights, the rotor radius of the variable-section blade portion at the corresponding height is different. Therefore, at the same wind turbine speed, the tip speed ratios corresponding to the variable-section blade portions at different heights are different. As the rotor radius decreases, the tip speed ratio also gradually decreases. In the case of a small tip speed ratio, blades with a larger chord length can capture more energy from the wind. Therefore, as the rotor radius decreases, the blade chord length also increases. In addition, since the root of the variable-section blade needs to bear a larger load, the design that the chord length of the variable-section blade gradually increases as the rotor radius decreases also makes the root of the variable-section blade stronger.

[0050] Among them, Figure 8 As shown, the chord length is the distance between the two end points of the blade on the same horizontal line, and the wind wheel radius is the vertical distance from the main axis to the line connecting the two end points of the blade on the same horizontal line.

[0051] Metal structural parts are embedded in the first variable-section blade 2 a , the uniform-section blade 2 b , the second variable-section blade 2 c and both ends of the cross brace 4 to enhance the structural strength and to connect flanges and the installation of the steel cable 5 .

[0052] The main shaft includes a connecting shaft 3a and a transmission shaft 3b. The upper end of the transmission shaft 3b is connected to the lower end of the connecting shaft 3a through an axial end flange 12a. The lower end of the connecting shaft 3a is connected to the end of the second variable-section blade 2c. The upper end of the connecting shaft 3a is connected to the top of the first variable-section blade 2a. The middle part of the connecting shaft 3a is connected to the equal-section blade 2b through a cross brace 4. In the present invention, the cross brace mainly bears the centrifugal force generated when the wind wheel rotates at high speed to prevent the wind wheel from being damaged due to excessive rotation speed. In addition, setting a cross brace is an effective method to increase the strength of the blade. The maximum shear stress and maximum bending moment acting on the blade are related to the spacing of the cross braces. The smaller the spacing between the cross braces, the smaller the maximum shear stress and maximum bending moment. If the spacing of the cross braces is reduced by 50%, the maximum shear stress is reduced by 50%, and the maximum bending moment is reduced by 75%.

[0053] Specifically, the connecting shaft 3a is a hollow shaft with flanges at the upper and lower ends. The upper end of the connecting shaft is connected to the top of the first variable-section blade 2a, and the lower end of the connecting shaft is connected to the end of the second variable-section blade 2c.

[0054] The blades 2b of uniform cross-section are connected to the main shaft via cross braces 4, and the cross braces 4 arranged at the same level are all located on the same horizontal line. Figure 2 This is a schematic diagram of the connection between the connecting shaft 3a and the cross brace 4. As shown in the figure, each cross brace 4 is bolted to the connecting shaft 3a through the main shaft connecting flange 8. Figure 3 The figure is a schematic diagram of the connection between the cross brace 4, the variable cross-section blade and the uniform cross-section blade 2b. As shown in the figure, the variable cross-section blade is bolted to the uniform cross-section blade 2b through the blade connection flange 10, and the connection between the main shaft and the blade is strengthened by the cross brace 4 to enhance the structural stability. Figure 1 Each uniform cross-section blade 2b is connected to three cross braces 4 via a cross brace-blade connecting flange 9.

[0055] Combination Figure 3 and Figure 4 A lifting ring is provided on the main shaft connection flange 8 at one-half of the connection shaft 3a. At the same time, a lifting ring is provided on the cross brace-blade connection flange 9 at both ends of the equal-section blades. The two ends of the steel cable 5 are respectively connected to the lifting rings at these two locations, thereby completing the oblique steel cable fixation of the main shaft and the equal-section blade 2b. In addition, according to the structural strength requirements of the fan, each of the above-mentioned lifting rings is connected to 1 to 2 steel cables 5. The steel cables here can convert the lateral centrifugal force of the blades into a vertical force, reduce the influence of the centrifugal force on the blades, and improve the strength of the blades.

[0056] In specific implementation, in order to improve the strength of the cross brace 4 and thus enhance the reliability of the overall structure, as Figure 7 As shown, metal plates 20 are embedded at both ends of the cross brace 4, and a steel pipe is embedded inside the cross brace 4. Both ends of the steel pipe are fixed to the embedded metal plates 20 by welding.

[0057] In specific implementation, when the number of annular blades evenly arranged circumferentially of the main shaft is greater than 3, lifting rings are set on the flanges at the upper end, lower end and bisection point of the uniform cross-section blade 2b, and steel cables are installed on the lifting rings. The steel cables are horizontally connected to the lifting rings of adjacent uniform cross-section blades to further improve the stability of the wind wheel.

[0058] Figure 4 , Figure 5 They are respectively a schematic diagram of the connection between the connecting shaft 3a and the first variable-section blade 2a, and a schematic diagram of the connection between the connecting shaft 3a and the second variable-section blade 2c. As shown in the figure, a top connecting flange 11a is installed on the top of the first variable-section blade 2a, and an upper end flange 12a is set on the top of the connecting shaft 3a. The top connecting flange 11a is connected to the upper end flange 12a through the top flange 1a, so as to achieve the fixation of the connecting shaft 3a and the first uniform-section blade 2b. The connection between each flange and the corresponding component is completed by bolt connection. Similarly, a bottom connecting flange 11b is installed at the bottom of the second variable-section blade 2c, and a lower end flange 12b is set at the bottom of the connecting shaft 3a. The bottom connecting flange 11b is connected to the lower end flange 12b through the bottom flange 1b, so as to achieve the fixation of the connecting shaft 3a and the second uniform-section blade 2b. The connection between each flange and the corresponding component is completed by bolt connection.

[0059] In the specific implementation, as the preferred solution of the present invention, all the fan blades and cross braces 4 are made of glass fiber composite materials, the connecting shaft 3a is made of 304 stainless steel, the transmission shaft 3b is made of 45 steel, all flanges and embedded structural parts are made of 304 stainless steel, and the bolt model connecting the flanges is M8, and the material is 304 stainless steel.

[0060] Example 2

[0061] This embodiment provides a high-efficiency annular vertical axis wind turbine based on the first embodiment. The annular vertical axis wind turbine comprises an annular vertical axis wind wheel and a generator, wherein the generator is located between the annular blades and the base.

[0062] like Figure 6 As shown, the upper end of the transmission shaft 3b is connected to the upper fan blade body through a bolt connection pair 14, and tapered roller bearings 15 are respectively provided at the upper and lower ends of the transmission shaft 3b. A sleeve is provided outside the transmission shaft 3b and the tapered roller bearing 15 to further effectively resist the rotation torque generated by the upper component. The lower end of the transmission shaft 3b is connected to the bottom end cover 16 of the sleeve to transmit all the gravity of the upper component downward.

[0063] In order to leave enough space at the bottom of the transmission shaft 3b to place the generator 6, and to transfer all the gravity of the fan blade components and the transmission shaft 3b components to the ground, and considering the convenience of installation, maintenance and self-locking, the base 7 support is designed to be supported by double-pass studs 17, and a large-diameter plate is set at the bottom as a base plate. The rotating shaft of the generator 6 is connected to the transmission shaft 3b extending from the upper end through a double diaphragm coupling 18, and the double diaphragm coupling 18 can transmit a large torque. The generator 6 is installed between the double diaphragm coupling 18 and the base plate, and the transmission shaft 3b is connected to the rotor of the generator 6 through a coupling. When working, the annular blades, the main shaft and the cross brace 4 are integrated designs, the annular blades, the main shaft and the cross brace 4 are used as rotors, and the generator 6 housing is used as a stator to generate electricity.

[0064] In specific implementation, as a preferred solution of the present invention, the pin hole at the end of the transmission shaft 3b is provided, and the transmission shaft 3b can be locked by inserting a pin through the pin hole on the sleeve of the bottom end cover.

[0065] In specific implementation, as a preferred solution of the present invention, the engine housing is made of cast aluminum, the base 7 and the sleeve bottom end cover 16 are made of 304 stainless steel, the transmission shaft 3b is made of aluminum alloy, and the tapered roller bearing 15 is made of bearing steel.

[0066] In order to further illustrate the technical solution and technical effect of the present invention, a high-efficiency annular vertical axis wind turbine of the present invention is compared with an existing vertical axis wind turbine. The wind turbine power generation is used as a standard for evaluating the working performance of the wind turbine. The wind turbine power generation calculation formula is as follows:

[0067]

[0068] Where P is the wind turbine power, ρ is the air density, A is the swept area, V is the wind speed, C P is the wind energy utilization coefficient.

[0069] The calculation formula of the swept area of ​​Darrieus vertical axis fan is:

[0070] S=H*D*0.657

[0071] Calculation formula for the swept area of ​​H-type vertical axis fan:

[0072] S=H*D

[0073] U-shaped vertical axis fan sweeping area calculation formula:

[0074] S=D*R*0.657+D*(HR)

[0075] Among them, S is the wind swept area of ​​the wind turbine, D is the diameter of the wind rotor, R is the radius of the wind rotor, and H is the height of the wind rotor.

[0076] The product of the wind rotor diameter and wind rotor height of the vertical axis fan is 25m^2, the wind speed is 12m / s, and the air density is 1.225kg / m 3 Under the condition of , numerical simulation is carried out on three different types of vertical axis wind turbines: Darrieus type, H type and U type, and the power generation of the three vertical axis wind turbines is compared according to the results of numerical simulation. The height-to-diameter ratio of the wind rotor of Darrieus type and H type vertical axis wind turbines is 1:1, and the height-to-diameter ratio of the wind rotor of ring type vertical axis wind turbine is 41:18.

[0077] Table 1 Wind turbine parameters and important calculation results

[0078]

[0079] It can be seen from the table that when the diameter and height of the axial fan rotor are the same, the wind speed and air density are the same, the power generation of the ring-type axial fan is increased by 33.83% and 3.58% respectively compared with the Darrieus type and H-type axial fans, and the wind energy utilization coefficient is increased by 3.73% and 22.13%.

[0080] Example 3

[0081] Based on the first and second embodiments, this embodiment proposes a small-sized, highly efficient annular vertical axis wind turbine. The existing small-sized wind turbines have a small diameter and height, resulting in a small blade chord length under a small chord-to-diameter ratio, which makes it difficult for the highly efficient annular vertical axis wind turbine to achieve self-starting under low wind speed conditions. To solve this problem, Fig. 9 As shown, the number of blades of a small-scale high-efficiency annular vertical axis wind turbine is increased. When the chord length of a single blade remains unchanged, increasing the number of blades can effectively increase the torque of the high-efficiency annular vertical axis wind turbine under low wind speed and low rotation speed conditions, and greatly improve the starting ability of the high-efficiency annular vertical axis wind turbine.

[0082] In addition, the small-sized and efficient annular vertical axis wind turbine has a small height, which results in a small size of the annular blades, and the centrifugal force on the blades is small. Therefore, the small-sized and efficient annular vertical axis wind turbine does not need to be installed with a cross brace, and a sling is installed instead of the cross brace. Wherein, different from Example 2, flanges are provided at the top, the end and the bisection point of the uniform cross-section blades and the main shaft, and a lifting ring is provided on the flange, and the lifting ring is used to realize the horizontal fixed connection between the uniform cross-section blades and the main shaft.

[0083] Reducing the number of cross braces can not only reduce the manufacturing cost of wind turbines, but also effectively improve the wind energy utilization coefficient of wind turbines. Taking a two-blade vertical axis wind turbine as an example, as shown in Table 2, the wind energy utilization coefficient of a single blade of a small and efficient annular vertical axis wind turbine without a cross brace is 0.2, and the total wind energy utilization coefficient is 0.4. When a set of cross braces is installed in the middle of the wind turbine, the wind energy utilization coefficient of a single blade of the wind turbine is reduced to 0.179, and the cross brace will generate negative torque during rotation, further reducing the wind energy utilization coefficient of the wind turbine, which results in the total wind energy utilization coefficient of the wind turbine with cross braces installed being only 0.334.

[0084] Table 2 Comparison of small annular vertical axis wind turbines with and without horizontal braces

[0085] type No cross brace blade With horizontal blades Single blade Cp 0.2 0.179 Cross brace Cp 0 -0.024 Total Cp of fan 0.4 0.334

[0086] Example 4

[0087] Based on Example 2 and Example 3, Example 4 provides a wind power generation system, including a plurality of high-efficiency annular vertical axis wind turbines as provided in Example 2 or Example 3, each annular vertical axis wind turbine is connected to the grid. For Example 4 of the present invention, since it corresponds to the technical content in the above embodiments, the description is relatively simple, and the relevant similarities can be referred to the description of the above embodiments, which will not be described in detail here.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention 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 replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-efficiency annular vertical axis wind turbine, characterized in that: include: Annular blades, a main shaft, a horizontal support and a base, the base is vertically mounted with the main shaft, a plurality of annular blades are evenly arranged along the circumference of the main shaft, the horizontal support connects the main shaft and the annular blades, and the annular blades, the main shaft and the horizontal support rotate synchronously; The annular blades are, from top to bottom, a first variable-section blade, a constant-section blade, and a second variable-section blade. The top of the first variable-section blade is connected to the main shaft via a flange, the bottom of the second variable-section blade is connected to the main shaft via a flange, the constant-section blade is arranged parallel to the main shaft, and the constant-section blade is connected to the main shaft via a horizontal support.

2. A high-efficiency annular vertical axis wind turbine according to claim 1, characterized in that: The horizontal support is a cross brace, which is made of glass fiber composite material and is used to connect the main shaft and blades with equal cross-sections to improve the structural stability of the wind wheel.

3. The high-efficiency annular vertical axis wind turbine according to claim 1, characterized in that: The horizontal support is a sling, which is a steel cable. Lifting rings are arranged on the flanges of the blades with equal cross-sections and the main shaft, and both ends of the sling are connected to the lifting rings to realize the connection between the main shaft and the blades with equal cross-sections.

4. The high-efficiency annular vertical axis wind turbine according to claim 1, characterized in that: The chord length of the first variable-section blade gradually decreases as the radius of the wind wheel increases, and for every 10% increase in the blade height, the chord length is 1.0 to 1.2 times the previous chord length; the chord length of the second variable-section blade gradually increases as the radius of the wind wheel decreases, and for every 10% decrease in the blade height, the chord length is 1.0 to 1.2 times the previous chord length; the ratio of the width to the chord length of the first variable-section blade and the second variable-section blade is 0.12 to 0.

25.

5. The high-efficiency annular vertical axis wind turbine according to claim 1, characterized in that: The blade chord length and width of the uniform cross-section vertical blade remain constant from top to bottom, and the ratio of the chord length to the wind wheel radius is less than 0.25, and the ratio of the uniform cross-section blade width to the chord length is 1.0-3.

0.

6. A high-efficiency annular vertical axis wind turbine according to claim 4 or 5, characterized in that: The chord length is the distance between the two end points of the blade on the same horizontal line, and the wind wheel radius is the vertical distance from the main axis to the line connecting the two end points of the blade on the same horizontal line.

7. The high-efficiency annular vertical axis wind turbine according to claim 2, characterized in that: Metal structural parts are embedded in the first variable-section blade, the equal-section blade, the second variable-section blade and both ends of the cross brace to enhance the structural strength, connect the flange and install the steel cable.

8. The high-efficiency annular vertical axis wind turbine according to claim 1, characterized in that: The main shaft includes a connecting shaft and a transmission shaft. The upper end of the transmission shaft is connected to the lower end of the connecting shaft through an axis end flange. The lower end of the connecting shaft is connected to the end of the second variable-section blade. The upper end of the connecting shaft is connected to the top of the first variable-section blade. The middle part of the connecting shaft is connected to the equal-section blade through a horizontal support.

9. The high-efficiency annular vertical axis wind turbine according to claim 8, characterized in that: Bearings are arranged at both ends of the transmission shaft, and the connection between the upper end of the transmission shaft and the lower end of the connecting shaft transmits the gravity of the upper end component to the rotating base through the bearings, while the bearings resist the rotational torque generated when the wind wheel rotates.

10. The high-efficiency annular vertical axis wind turbine according to claim 1, characterized in that: The uniform cross-section blades are connected to the main shaft via horizontal supports, and the horizontal supports arranged at the same level are all located on the same horizontal line. The first variable cross-section blades are connected to the uniform cross-section blades via flanges, and the second variable cross-section blades are connected to the uniform cross-section blades via flanges. A horizontal support is provided at the connection to connect to the main shaft to strengthen the structure of the connection.

11. The high-efficiency annular vertical axis wind turbine according to claim 2, characterized in that: The cross brace is connected to the blades with equal cross-sections via a flange, and the cross brace is connected to the main shaft via a flange.

12. The high-efficiency annular vertical axis wind turbine according to claim 1, characterized in that: The uniform cross-section blades are connected to the main shaft via a plurality of steel cables, and the steel cables are connected to the main shaft and the uniform cross-section blades via lifting rings. According to the structural strength requirements of the fan, each lifting ring is connected to 1 to 2 steel cables. When the number of annular blades evenly arranged circumferentially of the main shaft is greater than 3, the uniform cross-section blades are connected via steel cables.

13. A high-efficiency annular vertical axis wind turbine, characterized in that: It comprises a generator and a high-efficiency annular vertical axis wind wheel as described in any one of claims 1 to 12, wherein the generator is located between the transmission shaft and the base.

14. A high-efficiency annular vertical axis wind turbine according to claim 13, characterized in that: The transmission shaft is connected to the generator rotor through a coupling; when working, the annular blades, the main shaft and the horizontal support serve as the rotor, and the generator housing serves as the stator to generate electricity.

15. A wind power generation system, characterized in that: It comprises a plurality of high-efficiency annular vertical axis wind turbines as claimed in any one of claims 13 and 14, each of the high-efficiency annular vertical axis wind turbines is connected to the grid.

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