CN114576082B - Wind power generation device - Google Patents

Abstract

The invention provides a wind power generation device, the wind power generation device includes a wind wheel mechanism and a biaxial generator; the wind wheel mechanism includes a front wind wheel (100) and a rear wind wheel (200); the biaxial generator The first rotor and the second rotor are respectively arranged at both ends of the rotor, the front wind wheel (100) is connected with the first rotor through the first rotating shaft, and the rear wind wheel (200) is connected with the second rotating shaft through the second rotating shaft. The rotor is connected; the front wind wheel (100) includes a plurality of front blades (101); wherein, the front blades (101) include successively connected inner section blade spans, middle section blade spans and outer section blade spans, and the middle section blade spans The maximum chord length of the blade span is smaller than the maximum chord length of the outer blade span so as to guide fluid flow to the rear wind rotor (200). The wind power generating device of the present invention has the advantages of high power generation efficiency, compact arrangement and land saving.

Description

wind power plant

technical field

The invention relates to the technical field of wind power generation, in particular to a wind power generation device.

Background technique

Wind is one of the energy without pollution, it is inexhaustible and inexhaustible. It is very suitable for coastal islands, grasslands, pastoral areas, mountainous and plateau areas that are short of water, fuel, and inconvenient to use wind power to generate electricity according to local conditions. In addition, offshore wind power is also an important field of renewable energy development, an important force to promote wind power technology progress and industrial upgrading, and an important measure to promote energy structure adjustment.

my country is rich in wind energy resources, and the wind energy reserves that can be developed and utilized are about 1 billion kW, of which, the wind energy reserves on land are about 253 million kW (calculated from the height of 10m above the ground on land), and the wind energy reserves that can be developed and utilized at sea are about 750 million kW. A total of 1 billion kW.

A wind power generation device is an electric device that converts wind energy into mechanical work, which drives the rotor to rotate, and finally outputs alternating current. Wind power generation devices generally include components such as wind rotors, generators, steering devices, towers, speed-limiting safety mechanisms, and energy storage devices.

Although the wind power generation device in the prior art has the advantages of cleanness, good environmental benefits, renewable, short infrastructure construction period, and flexible installation scale, the existing wind power generation device still has the disadvantages of low power generation efficiency, large floor area, and instability. question.

Contents of the invention

The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, the embodiments of the present invention provide a wind power generation device, which has the advantages of high power generation efficiency, compact arrangement, and land saving.

According to the wind power generation device of the embodiment of the present invention, the wind power generation device includes a wind wheel mechanism and a biaxial generator; the wind wheel mechanism includes a front wind wheel and a rear wind wheel; the two ends of the biaxial generator are respectively set The first rotor and the second rotor, the front wind wheel is connected with the first rotor through the first rotating shaft, and the rear wind wheel is connected with the second rotor through the second rotating shaft; the front wind wheel includes a plurality of The front blade; wherein, the front blade includes an inner blade span, a middle blade span and an outer blade span connected in sequence, and the maximum chord length of the middle blade span is smaller than the maximum chord length of the outer blade span to guide fluid flow to the Rear wind wheel.

In the wind power generation device of the embodiment of the present invention, by setting the maximum chord length of the blade span in the middle section to be smaller than the maximum chord length of the blade span in the outer section, when the airflow passes through the front rotor, the airflow that is not blocked by the front blade can continue to flow toward the rear rotor. The kinetic energy loss of this part of the airflow is small, so it can effectively drive the rotation of the rear wind wheel and increase the rotation speed of the rear wind wheel, thus improving the overall power generation efficiency of the wind wheel assembly.

Optionally, the front blade is set such that: the maximum chord length of the middle blade span is smaller than the minimum chord length of the inner blade span.

Optionally, the rear rotor includes a plurality of rear blades, and the minimum chord length of the middle blade span of the rear blades is greater than the maximum chord length of the middle blade span of the front blades.

Optionally, the front blade is set such that: the minimum chord length of the inner blade span is greater than the maximum chord length of the outer blade span, and the inner blade span, the middle blade span and the outer blade span There is a smooth curve transition between the leaf spans.

Optionally, the rear blade is set such that: the minimum chord length of the inner blade span is greater than the maximum chord length of the middle blade span and the outer blade span, and the inner blade span, the There is a smooth curve transition between the middle blade span and the outer blade span.

Optionally, the ratio of the lengths of the inner blade span, the middle blade span and the outer blade span ranges from 1:1:1 to 1:1:1.3.

Optionally, the maximum chord length of the inner span of the front blade is located at 1/5 to 2/5 of the overall span of the blade.

Optionally, the maximum chord length of the inner span of the trailing blade is located at 1/10 to 3/10 of the overall span of the blade.

Optionally, along the direction from the inner blade span to the outer blade span, the thickness of the front blade gradually decreases; and/or, along the direction from the inner blade span to the outer blade span, the thickness of the rear blade slowing shrieking.

Optionally, the position where the relative thickness D/L of the inner span of the front blade is 50% is 15% to 17% from the root of the blade, and the relative thickness D/L of the inner span of the front blade is 40% % is at 19% to 21% of the distance from the blade root, and the position at which the relative thickness D/L of the inner span of the front blade is 35% is at 23% to 25% of the distance from the blade root, where D is the Thickness, L is the chord length of the blade.

Optionally, the position where the relative thickness D/L of the outer span of the front blade is 25% is 52% to 54% from the root of the blade, and the relative thickness D/L of the outer span of the front blade is 21% % is located at 66% to 72% of the distance from the root of the blade, and the position at which the relative thickness D/L of the outer span of the front blade is 15% is at the tip of the blade.

Optionally, the span of the rear blade is 60% to 80% of the span of the front blade.

Through the above technical solution, since the wind wheel mechanism of the wind power generation device includes a front wind wheel and a rear wind wheel coaxially arranged, the front wind wheel and the rear wind wheel can be driven by the wind to rotate at the same time, when the front wind When the wheel rotates, it drives the first rotating shaft connected to it to rotate, driving the first rotor in the biaxial generator to rotate to generate electricity; when the rear wind wheel rotates, it drives the second rotating shaft connected to it to rotate, driving the biaxial The second rotor in the generator rotates to generate electricity, so when the above-mentioned front wind wheel and rear wind wheel rotate at the same time, the first rotor and the second rotor of the biaxial generator rotate at the same time to generate electricity, which improves the power generation, and because The front wind wheel and the rear wind wheel can be co-arranged on the pillar of the same wind power generation device, so the number of wind power generation devices can be greatly reduced, and the area required for wind power generation can be reduced.

In one embodiment, the front blade is set such that the maximum chord length of the middle blade span is smaller than the maximum chord length of the outer blade span so as to guide fluid flow to the rear wind rotor. Therefore, when the airflow passes through the middle span of the front blade, the airflow that is not blocked by the middle span of the front blade can continue to flow to the rear rotor, and the kinetic energy loss of this part of the airflow is relatively small. Therefore, the rear wind wheel can be effectively driven to rotate, and the rotation speed of the rear wind wheel can be increased, so that the overall power generation efficiency of the wind wheel assembly can be improved.

Additional aspects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description serve to explain the principles of the invention.

Fig. 1 is a three-dimensional schematic diagram of a wind power generation device according to an embodiment of the present invention;

Fig. 2 is the schematic diagram of an embodiment of the front rotor of the wind power generation device of the present invention;

Fig. 3 is a schematic diagram of an embodiment of the rear rotor of the wind power generation device of the present invention.

Reference signs:

100-front wind wheel, 101-front blade, 200-rear wind wheel, 201-rear blade,

D-blade thickness, L-blade length.

Detailed ways

Embodiments of the invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below by referring to the figures are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

As shown in Figures 1-3, the wind power generation device of the present invention includes a wind wheel mechanism and a biaxial generator; the wind wheel mechanism includes a front wind wheel 100 and a rear wind wheel 200; The rotor and the second rotor, the front wind wheel 100 is connected to the first rotor through the first rotating shaft, and the rear wind wheel 200 is connected to the second rotor through the second rotating shaft; the front wind wheel 100 includes a plurality of front blades 101; wherein, the front blades 101 Including the inner blade span, the middle blade span and the outer blade span connected in sequence, the maximum chord length of the middle blade span is smaller than the maximum chord length of the outer blade span so as to guide the fluid flow to the rear rotor 200 .

In one embodiment, since the wind wheel assembly includes the front wind wheel 100 and the rear wind wheel 200 arranged coaxially, the front wind wheel 100 and the rear wind wheel 200 can be driven by the wind to rotate at the same time, when the front wind wheel 100 rotates, It drives the first rotating shaft connected to it to rotate, and drives the first rotor in the biaxial generator to rotate to generate electricity. When the rear wind wheel 200 rotates, it drives the second rotating shaft connected to it to rotate, driving the first rotor in the biaxial generator to rotate. The two rotors rotate to generate electricity, so when the above-mentioned front wind wheel 100 and the rear wind wheel 200 rotate at the same time, the first rotor and the second rotor of the biaxial generator rotate at the same time to generate electricity, which improves the power generation, and because the front wind wheel 100 and the rear wind wheel 200 can be co-arranged on the pillar of the same wind power generation device, so the number of wind power generation devices can be greatly reduced and the required area for wind power generation can be reduced.

In one embodiment, the front blade 101 is set such that the maximum chord length of the middle blade span is smaller than the maximum chord length of the outer blade span so as to guide the fluid flow to the rear rotor 200 . That is to say, when the airflow passes through the front rotor 100, the airflow that is not blocked by the front blades 101 can continue to flow to the rear rotor 200, and the kinetic energy loss of this part of the airflow is small, so it can effectively drive the rear rotor 200 to rotate , to increase the rotational speed of the rear wind rotor 200, thus improving the overall power generation efficiency of the wind rotor assembly.

It should be understood that the front blade 101 can be designed in various forms, as long as the chord length of the middle span of the front blade 101 is smaller than the chord length of the outer span.

In some embodiments, the maximum chord length of the inner blade span of the front blade 101 can be set to the minimum, that is, the minimum chord length of the middle blade span is greater than the maximum chord length of the inner blade span, so that the front blade 101 as a whole has a The chord length gradually decreases from the outer blade span to the inner blade span. Since the chord length of the middle blade span is smaller than that of the outer blade span, the blade of this shape can also allow more airflow to pass through the middle blade span. Thus, the rotation speed of the rear wind wheel 200 is increased. However, due to the small chord length of the inner blade span, the mechanical strength of the inner blade span is low, which may cause the problem of bending or even breaking of the blade from the root.

In some other embodiments, the chord length of the inner blade span of the front blade 101 can be set to be the same as the chord length of the middle blade span, so that the front blade 101 has a larger outer blade span and a smaller middle inner blade span. Since the chord length of the middle blade span is smaller than that of the outer blade span, the blade of this shape can also allow more airflow to pass through the middle blade span, thereby increasing the rotation speed of the rear wind wheel 200 . However, the chord length of the inner span of the blade of this shape is still small, resulting in low mechanical strength at the inner span, which may cause the problem of bending or even breaking of the blade from the root.

Therefore, in order to solve the above problem, in a preferred embodiment of the present invention, the front blade 101 is set such that the maximum chord length of the middle blade span is smaller than the minimum chord length of the inner blade span. That is to say, the blade of this shape is generally in a wavy shape with a large outer blade span, a small middle blade span, and a large inner blade span. Because the maximum chord length of the middle blade span is smaller than that of the outer blade The maximum chord length of the blade span, so it can also allow more airflow to pass through the middle blade span part, thereby increasing the rotation speed of the rear wind wheel 200, and the blade of this shape has a larger maximum chord length of the inner blade span, Thus, the mechanical strength of the inner blade span is guaranteed, and the problem of blade bending or even breaking from the root is fundamentally solved.

On the other hand, another benefit of the maximum chord length of the outer section blade span of the front blade 101 being greater than the maximum chord length of the middle section blade span is: because the chord length of the outer section blade span is larger, the outer section blade span of the front blade 101 It can be exposed to more airflow, and the moment arm from the outer blade to the first rotating shaft is longer than the moment arm from the middle blade to the first rotating shaft, so that the moment at the outer blade is larger, and the moment can make the object The angular acceleration can be obtained, and the moment of momentum of the object can be changed. For the same object, the greater the moment, the easier it is to change the rotation state. Therefore, this arrangement can make the front wind wheel 100 turn more easily, and can further improve The rotation speed of the front wind wheel 100.

The reason why the rotational speed of the front wind rotor 100 is given priority is because the front wind rotor 100 is first in contact with the airflow, which can maximize the conversion of the kinetic energy of the airflow, thereby effectively utilizing the wind force.

Further, the rear rotor 200 includes a plurality of rear blades 201 , and the minimum chord length of the middle blade span of the rear blades 201 is greater than the maximum chord length of the middle blade span of the front blade 101 . Such arrangement can make the airflow flowing from the front blade 101 to the rear blade 201 more fully contact the middle span of the rear blade 201 , thereby driving the rear blade 201 to increase the rotation speed.

Further, in one embodiment of the present invention, the front blade 101 is set such that: the minimum chord length of the inner blade span is greater than the maximum chord length of the outer blade span, and the inner blade span, the middle blade span and the outer blade span There is a smooth curve transition between the extensions. The advantage of such setting is: firstly, the front blade 101 is in the shape with the largest chord length of the inner blade span. Fracture problem. Secondly, the smooth curve transition between the inner blade span, the middle blade span and the outer blade span of the front blade 101 makes the blade overall streamlined, effectively reducing resistance when the blade rotates, thereby ensuring the speed of the front rotor 100 .

On the other hand, the trailing blade 201 can also be set such that the minimum chord length of the inner blade span is greater than the maximum chord length of the middle blade span and the outer blade span respectively, and the distance between the inner blade span, the middle blade span and the outer blade span There is a smooth curve transition between them. Likewise, through the above arrangement, the mechanical strength of the root of the trailing blade 201 is maximized, so that the problem of bending or even breaking of the blade from the root can be completely avoided. Secondly, the smooth curve transition between the inner blade span, the middle blade span and the outer blade span of the rear blade 201 makes the overall blade streamlined and effectively reduces resistance when the blade rotates, thereby ensuring the speed of the rear wind wheel 200 .

Since the outer blade span is exposed to more air flow, its torque is greater, which makes the front wind wheel 100 rotate more easily, and can further increase the rotation speed of the front wind wheel 100 . Therefore, in one embodiment of the present invention, the ratio of the lengths of the inner blade span, the middle blade span and the outer blade span ranges from 1:1:1 to 1:1:1.3. Such setting can ensure that the outer blade span is exposed to as much airflow as possible, thereby ensuring the rotation speed of the front rotor 100 .

In order to further improve the mechanical strength of the blade root, in one embodiment of the present invention, the maximum chord length of the inner blade span of the front blade 101 is located at 1/5 to 2/5 of the overall blade span, preferably, The maximum chord length of the inner span of the front blade 101 is located at 3/10 of the overall span of the blade, which helps to improve the mechanical strength of the blade root as much as possible under the premise of satisfying the fluid performance.

On the other hand, the maximum chord length of the inner blade span of the rear blade 201 is located at 1/10 to 3/10 of the overall length of the blade. Preferably, the maximum chord length of the inner blade span of the rear blade 201 is located at the 1/5 of the overall length, which helps to improve the mechanical strength of the blade root as much as possible under the premise of satisfying the fluid performance.

In addition, the maximum chord length of the outer blade span of the front blade 101 can also be set to be the same as the maximum chord length of the inner blade span, and the maximum chord length of the outer blade span can be located at any position of the outer blade span, for example , the maximum chord length may be located at the end of the outer blade span, that is, the maximum chord length may be located at the end of the blade. However, when the blade rotates, its tip will also be subjected to airflow resistance. In order to effectively reduce the resistance suffered by the blade tip, in one embodiment of the present invention, the maximum chord length of the outer blade span of the front blade 101 is located at this At 3/5 to 4/5 of the overall length of the blade, preferably, the maximum chord length of the outer blade span of the front blade 101 is located at 7/10 of the overall length of the blade. In other words, the maximum chord length is roughly located in the middle part of the outer blade span, so that the curve of one side of the outer blade span is in the shape of an approximate arc, so that the end of the outer blade span (that is, the end of the blade) ), which has a smaller chord length, thereby reducing its contact area with the airflow and reducing the resistance on the blade tip.

It should be understood that the longitudinal cross-section of the inner span of the front blade 101 can be configured in various shapes, for example, the longitudinal cross-section of the inner span of the front blade 101 can be wavy, triangular or trapezoidal.

In order to reduce the weight of the blade and improve the rotation efficiency of the blade, in one embodiment of the present invention, the thickness of the front blade 101 gradually decreases along the direction from the inner blade span to the outer blade span. The thickness of the rear blade 201 also decreases gradually from the blade span to the outer blade span. With the help of the gradually reduced thickness, the weight of the blade can be effectively reduced, and the root of the blade (that is, the maximum thickness part of the inner blade span) has a certain thickness to prevent the blade from bending and breaking.

In order to increase the rotation speed of the rear wind wheel 200, in one embodiment of the present invention, the position where the relative thickness D/L of the inner blade span of the front blade 101 is 50% is at a distance from 15% to 17% of the blade root, and the front The position where the relative thickness D/L of the inner blade span of the blade 101 is 40% is 19% to 21% away from the blade root, and the position where the relative thickness D/L of the inner blade span of the front blade 101 is 35% is at the distance from the blade root 23% to 25%, wherein, D is the thickness of the blade, and L is the chord length of the blade. This setting makes the change rate of the relative thickness of the inner blade span faster, and further reduces the energy attenuation caused by the inner blade span to the airflow, thereby giving more airflow to the rear wind rotor 200 to increase its rotational speed.

On the other hand, the outer span of the front blade 101 can also be designed, for example, the position where the relative thickness D/L of the outer span of the front blade 101 is 25% is at 52% to 54% from the blade root, and the front blade The position where the relative thickness D/L of the outer span of 101 is 21% is 66% to 72% from the blade root, and the position where the relative thickness D/L of the outer span of the front blade 101 is 15% is at the tip of the blade. Such setting makes the change rate of the relative thickness of the outer blade span of the front blade 101 slower, and further increases the contact time between the outer blade span and the airflow, thereby increasing the rotational speed of the front rotor 100 .

It should be understood that both sides of the front blade 101 can be designed as wavy curves, as long as the chord length relationship between the inner span, the middle span and the outer span of the blade is guaranteed.

In order to further optimize the rotation performance of the front wind wheel 100, in one embodiment of the present invention, the front blade 101 is counted as: its longitudinal section is a special shape with one side being a straight line and the other side being a protruding curve. . The protruding part can effectively contact the airflow, and the straight side can better reduce the resistance suffered by the blades when they rotate.

Since the front rotor 100 is first in contact with the airflow, the utilization rate of the front rotor 100 for the kinetic energy of the air is the largest. Therefore, in one embodiment of the present invention, the front rotor 100 is designed to be more compact than the rear rotor 200. In a large form, for example, the rear blade 201 spans 60% to 80% of the front blade 101 span, preferably, the rear blade 201 spans 70% of the front blade 101 span.

Further, in one embodiment of the present invention, the distance between the front wind rotor 100 and the rear wind rotor 200 is 0.25 times the diameter of the front wind rotor 100 . Within this range, the installation requirements of the front and rear wind rotors can be met, and the mutual interference between the front and rear wind rotors is small, thereby improving the utilization rate of wind energy.

Through the above technical proposal, when the front rotor 100 and the rear rotor 200 of the wind turbine mechanism of the wind power generation device of the present invention rotate simultaneously, the first rotor and the second rotor of the biaxial generator can be driven to rotate to generate electricity, which improves the power generation, and since the front wind rotor 100 and the rear wind rotor 200 can be arranged on the same pillar of the wind power generation device, the number of wind power generation devices can be greatly reduced, so that the area required for wind power generation is reduced.

In addition, since the front blade 101 is set such that the maximum chord length of the middle blade span is smaller than the maximum chord length of the outer blade span so as to guide fluid flow to the rear rotor 200, the problem of low combination efficiency of the front and rear rotors can be effectively improved, so that The overall power generation efficiency of the wind wheel assembly is improved.

In describing the present invention, it is to be understood that the terms "center", "longitudinal", "transverse", "stretch", "width", "thickness", "upper", "lower", "front", "Back", "Left", "Right", "Vertical", "Horizontal", "Top", "Bottom", "Inner", "Outer", "Clockwise", "Counterclockwise", "Axial" , "radial", "circumferential" and other indicated orientations or positional relationships are based on the orientations or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying the referred device or Elements must have certain orientations, be constructed and operate in certain orientations, and therefore should not be construed as limitations on the invention.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

In the present invention, unless otherwise clearly specified and limited, terms such as "installation", "connection", "connection" and "fixation" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection , or integrated; can be mechanically connected, can also be electrically connected or can communicate with each other; can be directly connected, can also be indirectly connected through an intermediary, can be the internal communication of two components or the interaction relationship between two components, Unless expressly defined otherwise. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

In the present invention, unless otherwise clearly specified and limited, the first feature may be in direct contact with the first feature or the first and second feature may be in direct contact with the second feature through an intermediary. touch. Moreover, "above", "above" and "above" the first feature on the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. "Below", "beneath" and "beneath" the first feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is less horizontally than the second feature.

As used herein, the terms "one embodiment," "some embodiments," "example," "specific examples," or "some examples" mean specific features, structures, materials, or features described in connection with the embodiment or example. A feature is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the described specific features, structures, materials or characteristics may be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples and features of different embodiments or examples described in this specification without conflicting with each other.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention, those skilled in the art can make the above-mentioned The embodiments are subject to changes, modifications, substitutions and variations.

Claims (9)

1. A wind power generator, characterized in that, the wind power generator comprises a wind wheel mechanism and a biaxial generator; The wind wheel mechanism includes a front wind wheel (100) and a rear wind wheel (200) arranged coaxially; Both ends of the biaxial generator are respectively provided with a first rotor and a second rotor, the front wind wheel (100) is connected to the first rotor through a first rotating shaft, and the rear wind wheel (200) is connected to the first rotor through a second the rotating shaft is connected with the second rotor; The front wind wheel (100) includes a plurality of front blades (101), and the rear wind wheel (200) includes a plurality of rear blades (201); Wherein, the front blade (101) includes an inner blade span, a middle blade span and an outer blade span connected in sequence, and the maximum chord length of the middle blade span is smaller than the maximum chord length of the outer blade span so as to guide fluid flow to The rear wind wheel (200); The position where the relative thickness D/L of the inner span of the front blade (101) is 50% is 15% to 17% from the root of the blade, and the relative thickness D/L of the inner span of the front blade (101) is The position of 40% is 19% to 21% from the blade root, and the position where the relative thickness D/L of the inner span of the front blade (101) is 35% is 23% to 25% from the blade root, wherein , D is the thickness of the blade, L is the chord length of the blade, the position where the relative thickness D/L of the outer span of the front blade (101) is 25% is 52% to 54% from the root of the blade, the front blade (101) The position where the relative thickness D/L of the outer span of the blade (101) is 21% is 66% to 72% away from the blade root, and the relative thickness D/L of the outer span of the front blade (101) is 15% The position is at the end of the blade, and the span length of the rear blade (201) is 60% to 80% of the span length of the front blade (101). 2. The wind power generation device according to claim 1, characterized in that the front blade (101) is set such that the maximum chord length of the middle blade span is smaller than the minimum chord length of the inner blade span. 3. The wind power generation device according to claim 2, characterized in that, the minimum chord length of the middle blade span of the rear blade (201) is greater than the maximum chord length of the middle blade span of the front blade (101). 4. The wind power generation device according to claim 2, characterized in that, the front blade (101) is set such that: the minimum chord length of the inner blade span is greater than the maximum chord length of the outer blade span, and There is a smooth curve transition among the inner blade span, the middle blade span and the outer blade span. 5. The wind power generation device according to claim 4, characterized in that, the rear blade (201) is set such that the minimum chord length of the inner blade span is greater than that of the middle blade span and the outer blade span respectively. The maximum chord length of the blade span, and the smooth curve transition among the inner blade span, the middle blade span and the outer blade span. 6. The wind power generation device according to claim 4, wherein the ratio of the lengths of the inner blade span, the middle blade span, and the outer blade span ranges from 1:1:1 to 1:1:1.3. 7. The wind power generation device according to claim 4, characterized in that, the maximum chord length of the inner span of the front blade (101) is located at 1/5 to 2/5 of the overall span of the blade. 8. The wind power generation device according to claim 7, characterized in that, the maximum chord length of the inner span of the rear blade (201) is located at 1/10 to 3/10 of the overall span of the blade. 9. The wind power generation device according to claim 4, characterized in that, along the direction from the inner blade span to the outer blade span, the thickness of the front blade (101) gradually decreases; and/or, along the inner blade span From the leaf span to the outer leaf span, the thickness of the rear blade (201) gradually decreases.

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