Blade assembly and wind generating set

Abstract

The embodiment of the invention provides a blade assembly and a wind generating set, the blade assembly comprises a blade and a resistance increasing device arranged on the blade, the resistance increasing device comprises a wind catching bag made of a flexible material and a bandage connected with the wind catching bag, the bandage is used for connecting the wind catching bag to the blade, the wind catching bag is provided with an air inlet, and the air inlet is communicated with the wind catching bag. And the air inlet faces the front edge side and / or the rear edge side of the blade, and the wind bag can be opened under the action of external wind, so that the resistance coefficient of the blade is increased. The resistance increasing device made of the flexible material is arranged on the blade, the resistance increasing device comprises the wind bag and the bandage connected with the wind bag, the wind bag can be opened under the action of external wind, and therefore the resistance coefficient of the blade is increased. Based on the characteristic that wind resistance is in positive correlation with the wind speed, the wind bag is arranged on the blade, so that the resistance coefficient of the blade can be increased under the action of the wind bag, and the problem of blade vibration caused by strong wind is solved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of wind power generation, and in particular to a blade assembly and a wind power generator set. Background Art

[0002] The blades of large turbine units are sometimes stored in large quantities in the yard before being hoisted. Under certain wind conditions (such as high wind speed, wind direction perpendicular to the span direction), the blades will cause first-order vibration in the swing direction. When the vibration amplitude is large, it will cause the blades to touch the ground, causing damage to the blade shape and structure or even scrapping; in addition, long-term and large-scale vibration will also cause fatigue load damage in this direction. At present, the main solution is to set a mesh sleeve on the blade tip, which can produce a turbulent effect to achieve vibration suppression of the blade.

[0003] However, the scheme of net sleeve vibration suppression has the following disadvantages: First, the reliability is insufficient. The net sleeve increases resistance, reduces lift and changes lift gradient through turbulence to achieve vibration suppression. The efficiency is low and the net sleeve usually needs to be installed in a large range of blades. However, at high wind speeds, the vibration suppression effect cannot be guaranteed. In practical applications, it is usually necessary to cooperate with the anchor fixation method. Second, the cost is high, it is difficult to recycle and reuse, and it is not convenient to transport. The net sleeve itself has the characteristics of customization and large material consumption, resulting in high cost. At the same time, since the net sleeves of different blade models cannot be shared, it is difficult to reuse the net sleeve, which further aggravates the cost problem. In addition, the net sleeve itself is large in size and inconvenient to transport, resulting in high transportation costs. Third, the net sleeve interferes with pneumatic accessories. At present, most blades are equipped with pneumatic accessories such as VG (vortex generator). Taking VG as an example, the installation range of VG is usually 80-90% from the root of the blade to the blade extension, which is also the installation range of the net sleeve. Therefore, it will interfere with the net sleeve, causing damage to the VG and difficulty in disassembling and installing the net sleeve. Summary of the invention

[0004] The present disclosure aims to at least solve the problems in the above-mentioned prior art or related technology that blade vibration can easily cause damage to the blade shape and structure or even scrap it, and the existing solution of suppressing vibration by installing a mesh sleeve on the blade has the disadvantages of insufficient reliability, high cost, non-reusability, interference between the mesh sleeve and pneumatic accessories, etc.

[0005] To achieve the above-mentioned purpose, a first aspect embodiment of the present disclosure provides a blade assembly, comprising a blade and a drag device arranged on the blade, the drag device comprising a wind bag made of a flexible material and a strap connected to the wind bag, the strap being used to connect the wind bag to the blade, the wind bag having an air inlet, and the air inlet facing the leading edge side and / or the trailing edge side of the blade, under the action of external wind, the wind bag can open, thereby increasing the drag coefficient of the blade.

[0006] In some embodiments, a portion of the air bag is located on the pressure side of the blade, and another portion of the air bag is located on the suction side of the blade, so that the flow rate of the airflow flowing through the pressure side and the suction side respectively is reduced, thereby reducing the pressure difference between the two sides of the blade.

[0007] In some embodiments, the flexible material is in the form of a square or rectangular sheet, one end of the flexible material is located on the pressure side of the blade, and the other end of the flexible material is located on the suction side of the blade. The straps are connected to both sides of the flexible material located in the span direction of the blade, so that the flexible material can be opened into a pocket shape under the action of external airflow.

[0008] In some embodiments, the straps include: cross straps and annular straps, two corners of the flexible material are located on the pressure side of the blade, and the other two corners are located on the suction side of the blade. On each of the pressure side and the suction side, the cross straps bring the two corners of the flexible material close to each other, thereby forming an air inlet between the two corners of the flexible material. The annular straps are connected to the two side edges of the middle part of the flexible material, and are wrapped around the circumference of the blade to prevent the flexible material from moving in the span direction of the blade.

[0009] In some embodiments, the wind pocket is arranged within a range of 2m to 10m from the tip of the blade, and / or the wind pocket covers 50% to 80% of the chord-wise width of the blade.

[0010] In some embodiments, the ventilating bag has hollow through holes.

[0011] In some embodiments, a plurality of resistance devices are provided, which are spaced apart in the span direction of the blade.

[0012] In some embodiments, the plurality of resistance devices include a first group of resistance devices disposed on a leading edge side of the blade and a second group of resistance devices disposed on a trailing edge side of the blade.

[0013] In some embodiments, the first group of resistance devices and the second group of resistance devices are alternately arranged in the span direction of the blade.

[0014] In some embodiments, the number of the first group of resistance devices is less than or equal to the number of the second group of resistance devices.

[0015] In some embodiments, the air inlets of at least a portion of the air bags of the first group of resistance devices and the air inlets of at least a portion of the air bags of the second group of resistance devices face each other.

[0016] In some embodiments, the number of the air bags is 3 to 6, the air bags are arranged at intervals along the span direction of the blade, and the distance between two adjacent air bags is 20 cm-50 cm.

[0017] In some embodiments, the width of each wind bag in the span direction of the blade is 1m-3m.

[0018] In some embodiments, the flexible material is any one or more of a fabric or a plastic sheet.

[0019] A second aspect of the present disclosure provides a wind turbine generator set, comprising a blade assembly as described in any one of the above embodiments.

[0020] The wind turbine generator set provided in the embodiment of this aspect has the blade assembly of any of the above embodiments, and thus has the beneficial effects of any of the above embodiments, which will not be described in detail here.

[0021] The blade assembly provided in the embodiment of this aspect is provided with a resistance device made of flexible material on the blade, and the resistance device includes a wind bag and a strap connected to the wind bag. The wind bag can be opened under the action of external wind, so that the resistance coefficient of the blade is increased. Based on the characteristic that wind resistance is positively correlated with wind speed, the wind bag is provided on the blade so that the resistance coefficient of the blade can be increased under the action of the wind bag, thereby solving the problem of yard vibration caused by strong winds. At the same time, since the wind bag made of flexible material is used in the embodiment of this aspect, it can be stacked when not in use and does not occupy extra space. It has the characteristics of small size and convenient transportation. Moreover, since the wind bag is not easy to be damaged and the material is common, it also has the characteristics of low cost and can be reused. The application scenarios of the present invention include but are not limited to the storage of blades in the yard, the operation of the blades after hoisting and before being connected to the grid, and the shutdown maintenance conditions during the operation of the blades.

[0022] Additional aspects and / or advantages of the present general inventive concept will be set forth in part in the following description and in part will be obvious from the description, or may be learned through practice of the present general inventive concept. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and other objects and features of the present invention will become more apparent through the following description in conjunction with the accompanying drawings which exemplarily illustrate an example, in which:

[0024] Figure 1 is a schematic diagram of a single blade drag device installed on the trailing edge side of a blade according to an embodiment of the present invention;

[0025] Figure 2 is a schematic diagram of a blade resistance device after being blown up according to an embodiment of the present invention;

[0026] Figure 3 is a schematic diagram of the installation positions of multiple blade resistance devices on the trailing edge side of a blade according to an embodiment of the present invention;

[0027] Figure 4 is a schematic diagram of a single blade drag device installed on the leading edge side of a blade according to an embodiment of the present invention;

[0028] Figure 5 is a schematic diagram of a plurality of blade resistance devices installed on the leading edge side of a blade according to an embodiment of the present invention;

[0029] Figure 6 is a schematic diagram of two blade resistance devices respectively installed on the leading edge side and the trailing edge side of the blade according to one embodiment of the present invention;

[0030] Figure 7 is a schematic diagram of a plurality of blade resistance devices respectively installed on the leading edge side and the trailing edge side of the blade according to one embodiment of the present invention;

[0031] Figure 8 is a schematic diagram of two blade resistance devices being relatively installed on the leading edge side and the trailing edge side of a blade according to an embodiment of the present invention;

[0032] Fig. 9 is a schematic diagram of a plurality of blade resistance devices being relatively installed on the leading edge side and the trailing edge side of a blade respectively according to an embodiment of the present invention;

[0033] Fig.10 is a schematic diagram of a blade resistance device with ventilation holes according to an embodiment of the present invention;

[0034] Fig.11 It is a schematic diagram of the verification result of the drag adding effect on the blade by the blade drag adding device according to an embodiment of the present invention.

[0035] Fig.12 is a single vibration direction stall-induced flutter model according to an embodiment of the present invention;

[0036] Fig.13 is an arbitrary vibration direction stall-induced flutter model according to an embodiment of the present invention;

[0037] Fig.14 is a simulation diagram of the effect of a blade resistance device on a flow field on a blade surface according to an embodiment of the present invention;

[0038] Fig.15 is another simulation diagram of the effect of the blade resistance device on the flow field on the blade surface according to one embodiment of the present invention;

[0039] Fig.16 and Fig.17 Schematic diagrams showing the results of calculating the damping coefficient of a blade without the resistance device of the present invention and a blade with the resistance device of the present invention using field parameters are shown respectively.

[0040] Figures 1 to 17 Description of reference numerals:

[0041] 10 air bags, 110 air inlets, 120 hollow through holes,

[0042] 20 straps, 210 cross straps, 220 ring straps,

[0043] 30 blades, 310 suction side, 320 pressure side, 330 trailing edge side, 340 leading edge side. DETAILED DESCRIPTION

[0044] The following specific embodiments are provided to help the reader gain a comprehensive understanding of the methods, devices and / or systems described herein. However, various changes, modifications and equivalents of the methods, devices and / or systems described herein will be clear after understanding the disclosure of the present application. For example, the order of operations described herein is only an example and is not limited to those orders set forth herein, but can be changed as will be clear after understanding the disclosure of the present disclosure, except for operations that must occur in a specific order. In addition, for greater clarity and simplicity, descriptions of features known in the art may be omitted.

[0045] The features described herein may be implemented in different forms and should not be construed as being limited to the examples described herein. Rather, the examples described herein have been provided to illustrate only some of the many possible ways to implement the methods, devices, and / or systems described herein, which will be clear after understanding the disclosure of the present disclosure.

[0046] As used herein, the term "and / or" includes any one of the associated listed items and any combination of any two or more.

[0047] Although terms such as "first", "second", and "third" may be used herein to describe various members, components, regions, layers, or portions, these members, components, regions, layers, or portions should not be limited by these terms. Instead, these terms are only used to distinguish one member, component, region, layer, or portion from another member, component, region, layer, or portion. Therefore, without departing from the teachings of the examples described herein, the first member, first component, first region, first layer, or first portion referred to in the examples may also be referred to as the second member, second component, second region, second layer, or second portion.

[0048] In the specification, when an element such as a layer, a region or a substrate is described as being “on”, “connected to” or “coupled to” another element, the element may be directly “on”, “connected to” or “coupled to” another element, or one or more other elements may be present therebetween. Conversely, when an element is described as being “directly on”, “directly connected to” or “directly coupled to” another element, other elements may not be present therebetween.

[0049] The terms used herein are only used to describe various examples and are not intended to limit the disclosure. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms "comprise", "include" and "have" indicate the presence of the described features, quantities, operations, components, elements and / or combinations thereof, but do not exclude the presence or addition of one or more other features, quantities, operations, components, elements and / or combinations thereof. The term "plurality" represents any number of two and more than two.

[0050] The definitions of directional terms such as "upper", "lower", "top" and "bottom" in the present disclosure are all based on the directional definitions when the product is in normal use and placed upright.

[0051] Unless otherwise defined, all terms used herein, including technical terms and scientific terms, have the same meaning as those generally understood by ordinary technicians in the field to which the present invention belongs after understanding the present invention. Unless explicitly defined as such herein, terms such as those defined in general dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant field and the present invention, and should not be interpreted in an idealized or overly formal way.

[0052] Furthermore, in the description of the examples, when it is considered that a detailed description of a well-known related construction or function will cause vague interpretation of the present invention, such a detailed description will be omitted.

[0053] The following will be combined Figures 1 to 15 A blade assembly and a wind turbine generator set provided by embodiments of the present disclosure are introduced.

[0054] like Figures 1 to 9 As shown, a first aspect embodiment of the present disclosure provides a blade assembly, including a blade 30 and a resistance device arranged on the blade 30, the resistance device including a scooter bag 10 made of a flexible material and a strap 20 connected to the scooter bag 10, the strap 20 is used to connect the scooter bag 10 to the blade 30, the scooter bag 10 has an air inlet 110, and the air inlet 110 faces the leading edge side 340 and / or the trailing edge side 330 of the blade 30, under the action of external wind, the scooter bag 10 can be opened, thereby increasing the damping of the blade 30.

[0055] The blade assembly provided by the embodiment of this aspect is provided with a resistance device made of a flexible material on the blade 30, and the resistance device includes a wind bag 10 and a strap 20 connected to the wind bag 10. The wind bag 10 can be opened under the action of external wind, so that the resistance coefficient of the blade 30 is increased. Based on the characteristic that wind resistance is positively correlated with wind speed, the wind bag 10 is provided on the blade 30 so that the resistance coefficient of the blade 30 can be increased under the action of the wind bag 10, thereby solving the problem of blade vibration caused by strong winds. At the same time, since the wind bag 10 made of a flexible material is used in the embodiment of this aspect, it can be stacked when not in use, occupies a small space, has a small volume, and is easy to transport. Moreover, since the wind bag 10 is not easy to be damaged and the material is easy to obtain, it also has the characteristics of low cost and can be repeatedly used.

[0056] like Figure 1 , Figure 2 and Figure 3 As shown, the resistance device can be arranged at the trailing edge side 330 of the blade 30, and in this state, the air inlet 110 faces the leading edge side 340. Figure 4 and Figure 5 As shown, the resistance device can be arranged on the leading edge side 340 of the blade 30, and in this state, the air inlet 110 faces the trailing edge side 330. Figure 6 , Figure 7 , Figure 8 and Fig. 9 As shown, resistance devices may also be provided on both the leading edge side 340 and the trailing edge side 330 of the blade 30, so that the vibration suppression effect can be exerted regardless of the direction from which the external wind blows.

[0057] The application scenarios of the present invention include, but are not limited to, storage of blades 30 in a yard, before grid connection after the blades 30 are hoisted, and shutdown maintenance of the blades 30 during operation.

[0058] It is worth noting that since the relationship between wind resistance and wind speed is a quadratic positive correlation, the greater the wind speed, the greater the added damping. By providing the windbag 10, the wind resistance can be efficiently utilized to increase the damping of the blade 30 and avoid stall-induced flutter of the blade 30.

[0059] Furthermore, in some embodiments, Figures 1 to 9 As shown, the strap 20 connects the airbag 10 to the blade 30 so that there is a gap between the airbag 10 and the outer surface of the blade 30 in the working state, thereby increasing the drag coefficient of the blade 30 by utilizing wind resistance without changing the aerodynamic shape of the blade 30.

[0060] In these embodiments, the air bag 10 is connected to the blade 30 by the straps 20, so that the air bag 10 and the blade 30 are relatively independent. When a resistance device is not needed, the air bag 10 and the blade 30 can be separated by loosening the straps 20, so that disassembly is convenient. Moreover, in the working state, there is a gap between the air bag 10 and the outer surface of the blade 30, thereby increasing the drag coefficient of the blade 30 without changing the aerodynamic shape of the blade 30.

[0061] The method of connecting the air bag 10 to the blade 30 by the strap 20 can avoid interference with the pneumatic accessories on the blade 30, and solves the problem that the net sleeve in the related art is easy to interfere with the pneumatic accessories such as VG, causing damage to the VG and difficulty in installing and removing the net sleeve. In addition, since the air bag 10 does not need to follow the shape of the blade, it can be applied to blades of different airfoils and has good versatility.

[0062] In some embodiments, a portion of the air bag 10 is located on the pressure side 320 of the blade 30, and another portion of the air bag 10 is located on the suction side 310 of the blade 30, so that the flow rate of the airflow flowing through the pressure side 320 and the suction side 310 respectively is reduced, thereby reducing the pressure difference on both sides of the blade 30, reducing the lift of the blade, and increasing the damping of the blade, thereby effectively suppressing the vibration of the blade.

[0063] Normally, when the airflow flows through the periphery of the blade 30, the airflow velocity on the suction side 310 of the blade 30 is greater than the airflow velocity on the pressure side 320 of the blade 30. According to the Bernoulli equation, the greater the gas velocity, the smaller the pressure. Therefore, the pressure on the pressure side 320 of the blade 30 is greater, and there is a certain pressure difference between the suction side 310 and the pressure side 320, so that the blade 30 obtains lift. The airbag 10 is provided on both the suction side 310 and the pressure side 320 of the blade 30, so that the airbag 10 can block the airflow on the suction side 310 and the pressure side 320 of the blade 30, so that the airflow can form vortices on the suction side 310 and the pressure side 320 of the blade 30, reduce the airflow velocity, thereby balancing the pressure on the suction side 310 and the pressure side 320 of the blade 30, reducing the pressure difference between the suction side 310 and the pressure side 320 of the blade 30, reducing the lift, and then reducing the vibration of the blade 30.

[0064] According to the Bernoulli equation, the greater the gas flow rate, the smaller the pressure. The air flow speed on the pressure side 320 of the blade 30 surface is slow and the pressure is high, while the pressure on the suction side 310 is low, which will generate a pressure from the pressure side 320 toward the suction side 310, causing the blade 30 to swing in one direction; and when the wind conditions change, there is a probability that the pressure on both sides will shift. If the wind changes periodically, it will cause the blade 30 to swing frequently and produce vortex-induced vibration. By reducing the airflow velocity flowing through the surface of the blade 30, the pressure difference on both sides of the blade 30 can be reduced, thereby reducing vortex-induced vibration and suppressing the vibration of the blade 30.

[0065] In some embodiments, the flexible material is in the form of a square or rectangular sheet, one end of the flexible material is located on the pressure side 320 of the blade 30, and the other end of the flexible material is located on the suction side 310 of the blade 30. The strap 20 is connected to both sides of the flexible material located on the upward direction of the blade 30, so that the flexible material can be opened into a pocket shape under the action of external airflow.

[0066] When the airflow flows over the surface of the blade and enters the air bag, and then flows out from both sides of the air bag, a negative pressure area is formed on the side of the air bag 10 away from the blade. The pressure difference on both sides forms a backward pulling force on the blade. The pulling force forms a resistance that is roughly consistent with the vibration direction of the blade, thereby suppressing the vibration of the blade.

[0067] In these embodiments, the air bag 10 is made of a square or rectangular sheet of flexible material, and the pressure side 320 and the suction side 310 of the blade 30 are made of a piece of flexible material. In this way, the flexible material can be opened into a pocket shape under the action of the external airflow, and the airflows on the suction side 310 and the pressure side 320 can converge into the air bag 10, thereby propping up the air bag 10 to form a pocket shape, thereby suppressing the vibration of the blade 30; and the production of the air bag 10 is facilitated, and there is no need to separately produce the air bag 10 on the suction side 310 and the pressure side 320, thereby simplifying the structure of the air bag 10 and facilitating the installation of the air bag 10.

[0068] Furthermore, if Figure 1 As shown, the air bag 10 made of a flexible material can be formed into a pocket shape with an air inlet 110 on the surface of the blade 30. When there is no airflow to support the air bag 10, that is, when there is no wind or little wind, the air bag 10 naturally droops. The air bag 10 located above the blade 30 is attached to the surface of the blade 30, and the air bag 10 located below the blade 30 is drooped under the blade 30 due to gravity; Figure 2 As shown, in the case of strong winds, the airflow can open the air bag 10 through the air inlet 110, so that the air bag 10 is blown into a hemispherical curved shape.

[0069] In some embodiments, Figure 1 As shown, the strap 20 includes: a cross strap 210 and an annular strap 220. The flexible material is generally square or rectangular. Two corners of the flexible material are located on the pressure side 320 of the blade 30, and the other two corners are located on the suction side 310 of the blade 30. On each side of the pressure side 320 and the suction side 310, the cross strap 210 brings the two corners of the flexible material close to each other. Specifically, on the pressure side 320 of the blade 30, the cross strap 210 is fixed at two corners and crosses each other to fix the chord-wise position of the flexible sheet, so that the two corners of the flexible material are brought close to each other by the cross strap 210, and then at the two corners of the flexible material An air inlet 110 is formed between the blade 30, so that wind can enter from the air inlet 110 to stretch the flexible material to form a pocket; similarly, on the suction side 310 of the blade 30, the cross straps 210 are also fixed at two corners and cross each other, so that the two corners of the flexible material are brought close to each other through the cross straps 210, and then an air inlet 110 is formed between the two corners of the flexible material, so that wind can enter from the air inlet 110 to stretch the flexible material to form a pocket; further, the annular strap 220 is connected to the two side edges of the middle of the flexible material, and is fixedly wrapped around the circumference of the blade 30, for fixing the spanwise position of the flexible material, and preventing the flexible material from moving in the spanwise direction of the blade 30. As an example, since the annular binding rope 220 is connected to both sides of the flexible sheet body, the approximately middle position of the left and right sides of the flexible sheet body can be fixed on the blade, thereby preventing the flexible sheet body from moving in the spanwise direction of the blade.

[0070] As an example, the strap 20 may be a strap 20 with a tightener, a rope, etc. The strap 20 with a tightener can be directly tied to the surface of the blade 30 through the tightener, which is convenient for operation; the rope has a low cost and can be tied to the surface of the blade 30, and is fixed to the blade 30 by tying a knot or hook, etc., and the connection between the blade 30 and the blade 30 is simple.

[0071] In some embodiments, the air bag 10 is arranged within a range of 2m to 10m from the tip of the blade 30. The air bag 10 is installed in an area close to the tip of the blade 30, and the distance between the air bag 10 and the tip is greater than or equal to 2m and less than or equal to 10m. Within this range, on the one hand, the range within 2m on one side near the tip of the blade 30 can be avoided. Generally speaking, the inner chord length of the blade 30 2m from the tip is too small, and it is not convenient to install the resistance device. Therefore, the resistance device is installed on the blade 30 2m away from the tip and installed in sequence toward the inside; on the other hand, based on the characteristic that wind resistance is positively correlated with wind speed, the resistance device is installed within a range of 10m near the tip of the blade. The high drag coefficient resistance device in the range near the tip of the blade can be used to solve the problem of yard vibration caused by strong winds in the wind direction from the leading edge to the trailing edge and from the trailing edge to the leading edge, while considering the strength of each component to ensure that each component does not fail under strong wind conditions; in addition, the installation range is from 2m to 10m from the tip of the blade, which can also avoid interference with aerodynamic accessories installed on the blade 30, such as vortex generators.

[0072] In some embodiments, the wind bag 10 covers 50% to 80% of the chord-wise width of the blade 30. Within this range, the wind bag 10 covers a sufficient chord-wise width of the blade 30 to solve the problem of blade vibration caused by strong wind in the wind direction from the leading edge to the trailing edge and from the trailing edge to the leading edge, and can effectively suppress vibration, while the wind bag 10 will not cover too large a chord-wise width of the blade 30, so that it is difficult to be propped up by the wind to form a pocket shape.

[0073] Furthermore, in some embodiments, Fig.10 As shown, the air bag 10 has a hollow through hole 120, which is used to reduce the wind resistance of the air bag 10. The hollow through hole 120 is easy to process, and can be directly punched on the air bag 10. Through a simple process, the wind resistance of the air bag 10 can be reduced, and the problem of the strap 20 being broken due to excessive resistance of the air bag 10 can be prevented, and the pressure of the strap 20 on the local surface of the blade 30 can be prevented from being too large, causing damage to the surface of the blade 30.

[0074] According to some embodiments, the resistance device is provided as one, and the air bag 10 may be one or multiple air bags connected to each other as one body, and the length of the air bag 10 in the span direction of the blade is set according to the actual vibration suppression needs. As an example, in the case of providing a single resistance device, the length of the air bag 10 may be relatively large, and in this case, multiple sets of straps may be used to fix the air bag 10 on the blade 30 in the span direction of the blade.

[0075] In some embodiments, Figure 3 , Figure 5 , Figure 7 and Fig. 9As shown, the resistance device is provided in multiple numbers and is arranged at intervals in the span direction of the blade 30. Such arrangement can not only reduce the length of each resistance device, avoid the length of a single air bag 10 being too long and increasing the difficulty of installation, but also have sufficient length to block the wind and ensure the vibration suppression effect of the blade 30. When the air bag is blown by the wind, the air bag 10 will be subject to great aerodynamic resistance, so the solution of using an integral air bag 10 will have higher requirements on the strength of the components, while the use of multiple resistance devices in this embodiment can disperse the force and improve the reliability of the components.

[0076] In some embodiments, the plurality of resistance devices include a first group of resistance devices disposed on a leading edge side 340 of the blade 30 and a second group of resistance devices disposed on a trailing edge side 330 of the blade 30 .

[0077] In some embodiments, Figure 6 and Figure 7 As shown, the first group of resistance devices and the second group of resistance devices are alternately arranged in the span direction of the blade 30.

[0078] In some embodiments, the number of the first group of resistance devices is less than or equal to the number of the second group of resistance devices.

[0079] In these embodiments, the resistance devices are grouped according to their orientations. As an example, the resistance devices arranged on the leading edge side 340 of the blade 30 are grouped as the first group of resistance devices, and the resistance devices arranged on the trailing edge side 330 of the blade 30 are grouped as the second group of resistance devices. The number of the first group of resistance devices and the second group of resistance devices may be approximately the same, and are alternately arranged in the span direction of the blade 30; alternatively, the number of the first group of resistance devices is less than the number of the second group of resistance devices, in which case they may not be arranged in an alternating manner.

[0080] In some embodiments, Figure 8 and Fig. 9 As shown, the air inlet 110 of the air bag 10 of at least a part of the first group of resistance devices and the air inlet 110 of the air bag 10 of at least a part of the second group of resistance devices face each other. Specifically, the first group of resistance devices and the second group of resistance devices can be arranged overlappingly in the span direction of the blade 30, and the air inlet 110 of the first group of resistance devices and the air inlet 110 of the second group of resistance devices face each other; the first group of resistance devices and the second group of resistance devices can also be arranged partially overlappingly in the span direction of the blade 30, that is, a part of the air inlet 110 of the first group of resistance devices and a part of the air inlet 110 of the second group of resistance devices face each other.

[0081] Figure 1The schematic diagram of a single drag device installed on a blade 30 is shown. Optionally, in practical applications, in some embodiments, the number of the wind bags 10 is 3 to 6, which are installed sequentially from 2 m away from the blade tip to the blade root, such as Figure 3 , Figure 5 , Figure 7 and Fig. 9 shown.

[0082] Furthermore, the air bags 10 are arranged at intervals along the span direction of the blade 30, and the distance between two adjacent air bags 10 is 20cm-50cm. This arrangement can avoid mutual interference between two adjacent resistance devices, and will not affect the vibration suppression effect by being too far apart.

[0083] In some embodiments, the width of each of the air bags 10 in the direction of the blade 30 is 1m-3m. Within this range, it has a sufficient length to effectively suppress vibration, but does not cause excessive resistance due to the excessive width of a single air bag 10 in the direction of the blade 30, which may easily break the strap 20.

[0084] In some embodiments, the flexible material is any one or more of fabric or plastic cloth.

[0085] In these embodiments, the wind bag 10 is made of a flexible material, and the flexible material is any one or more combinations of fabrics or plastic cloths. The fabrics may include relatively strong fabrics such as canvas, polyester cloth, nylon cloth, and Oxford cloth. The above-mentioned flexible materials have the advantages of low cost, strength, light weight, easy storage, low transportation cost, etc., and can be recycled and reused; in addition, when the wind turbine is hoisted and there is no need to set up a resistance device, the resistance device can be detached from the blade 30 by disconnecting the strap 20, which is convenient for disassembly, and because the above-mentioned flexible material is light in weight, the resistance device can fall freely and will not injure the staff.

[0086] In some embodiments, the resistance device also includes a bracket (not shown in the figure), which is located inside the air bag 10 and is used to open the air bag 10 made of a flexible material. As an example, the bracket can optionally be a plastic stick that can be elastically deformed, etc., to support the air bag 10. Since the air bag 10 itself also has a certain weight, it may not be able to open when the wind force is small, and therefore it is difficult to play a vibration suppression role. According to some embodiments of the present application, by providing a bracket, the air bag 10 is kept in an open state, so that even when the wind force is small, the vibration of the blades 30 can be suppressed.

[0087] As an example, optionally, the bracket can be in an arc shape, so as to expand the air bag 10 into a hemispherical shape; further, the bracket can be a foldable bracket, and when the resistance device is not needed, the bracket is folded and the air bag 10 is not propped up, thereby saving space and facilitating transportation, etc.; when the resistance device is needed, the bracket is propped up so that the bracket props up the air bag 10 into a hemispherical shape, thereby suppressing the vibration of the blades 30.

[0088] A second aspect of the present disclosure provides a wind turbine generator set, comprising a blade assembly as described in any one of the above embodiments.

[0089] The wind turbine generator set provided in the embodiment of this aspect has the blade assembly of any of the above embodiments, and thus has the beneficial effects of any of the above embodiments, which will not be described in detail here.

[0090] The dynamic working process of the resistance adding device of the embodiment of the present application is described below in conjunction with the accompanying drawings. Figure 1 As shown, in the case of no wind or light wind, the airbag 10 made of flexible material naturally droops, and the upper section is attached to the upper surface of the blade 30. Due to the fixation of the cross straps 210, an inward closing is formed on the airbag 10, and the lower section of the airbag 10 is used as a whole by gravity and hangs below the lower surface of the blade 30.

[0091] Take the case where the air inlet 110 of the airbag 10 faces the leading edge 340 of the blade 30 as an example. When a certain wind speed is reached, such as 8m / s or more, and the wind direction is from the leading edge to the trailing edge or at a certain angle, such as less than 45°, the airbag 10 (such as a canvas bag) will be blown into a hemispherical curved surface due to the pressure difference resistance. At the same time, the wind passing through the blade 30 will form turbulent vortices due to separation, causing the upper and lower sides of the blade 30 to shake. When the wind direction forms a certain angle with the chord direction of the blade 30, the wind resistance exerts a lateral force on the airbag 10, that is, a spanwise force component. At this time, Figure 1 The annular strap 220 in the airbag 10 provides a constraint to prevent the drag device from moving in the span direction. Figure 2 shown.

[0092] When the wind direction is from the trailing edge to the leading edge, or at a certain angle, such as less than 45°, and the wind direction is along the span direction of the blade 30, the shape of the canvas is slightly affected at low wind speeds. When the wind speed is high, such as greater than 10m / s, the canvas is affected by the wind and is pressed tightly against the surface of the blade 30.

[0093] It is understandable that the embodiment in which the air inlet 110 of the air bag 10 faces the trailing edge 330 of the blade 30 is similar to the above-mentioned embodiment in which the air inlet 110 of the air bag 10 faces the leading edge 340 of the blade 30, and will not be described in detail here.

[0094] like Fig.11 As shown, in a specific embodiment of the present invention, a 95m blade using the blade resistance device of the present invention is placed in a yard as a test object, and the test verification has been completed for more than 300 hours. The verification period includes winds of more than 18m / s, and the wind directions include the front edge to the rear edge and at a certain angle, and the rear edge to the front edge and at a certain angle. Fig.11 As shown, Fig.11 The upper middle figure (a) shows the original collected data of the acceleration sensor, and the lower figure (b) shows the vibration diagram, which is the vibration result after the original collected data is reset to zero. It can be clearly seen from the figure that the maximum acceleration during the verification period is about 0.1g (g is the acceleration of gravity), which is less than the threshold value (0.15-0.2g). No obvious vibration occurred during the verification period of the unit of this embodiment.

[0095] In order to better understand the present invention, a simple analysis is made below on the principle of stall-induced flutter and the mechanism by which the drag device of the present invention can suppress vibration.

[0096] Fig.12 It is a stall-induced flutter model with a single vibration direction. In this simplified model, the airfoil vibrates in a single degree of freedom along the direction perpendicular to the incoming flow.

[0097] According to the simplified single-degree-of-freedom model, vibration causes periodic changes in the angle of attack, which in turn causes periodic changes in the aerodynamic force in that direction. When the direction of the increase in aerodynamic force is the same as the direction of vibration, or in other words, there is a phase difference between the aerodynamic force and the vibration displacement within a vibration cycle, the aerodynamic force does positive work within a vibration cycle, resulting in the accumulation of total system energy. The mechanical energy of the incoming flow is converted into the elastic potential energy of the bending deformation of the blade, resulting in a tendency for the blade deformation to increase, which is manifested as self-excited vibration with a continuous increase in the blade deflection. For example, at a large angle of attack, the blade vibrates upward, and the angle of attack α0 reduces the lift coefficient C. L Increase, C L If the vibration direction component increases and its direction is the same as the vibration direction, the vibration will tend to increase.

[0098] According to the technical solution of the present invention, by providing a resistance device, the pressure difference between the pressure side and the suction side of the blade can be reduced, thereby reducing the lift and reducing the energy causing the blade flutter.

[0099] By generalizing the previous single-degree-of-freedom simplified model, the stall-induced flutter model of the airfoil in any vibration direction x can be obtained. Fig.13 The stall-induced flutter model of the airfoil in any vibration direction is shown. Since the aerodynamic forces in other directions do not do work, only the aerodynamic resultant force of the blade airfoil in the vibration direction is discussed below. The aerodynamic resultant force Fx and F0 in the vibration direction x can be expressed by the following equations (2) and (3), respectively:

[0100]

[0101]

[0102] in,

[0103]

[0104] Based on equations (2) and (3), the aerodynamic force F under dynamic conditions is x The aerodynamic resultant force F0 in the steady state is linearized at the equilibrium point x=0, that is, a first-order Taylor expansion is performed according to the following formula (4) to obtain the equivalent damping coefficient η of the model, which can be expressed by the following formula (5).

[0105] F x ≈F0-ηx Formula (4)

[0106]

[0107] Among them, in the above formula (2), formula (3), formula (4), formula (5), the meaning of each parameter is as follows:

[0108] η-equivalent damping coefficient;

[0109] F x - Aerodynamic resultant force in unsteady state;

[0110] F0-aerodynamic force in steady state;

[0111] ρ - air density;

[0112] c-chord length;

[0113] W-the combined speed of the downflow wind speed and the vibration wind speed in the unsteady state;

[0114] W0-incoming flow velocity in steady state;

[0115] C L - lift coefficient;

[0116] C D - drag coefficient;

[0117] α-angle of attack in unsteady state;

[0118] α0 - angle of attack in steady state;

[0119] φ - inflow angle in unsteady state;

[0120] φ0-inflow angle in steady state;

[0121] θ-angle between vibration direction and reference line;

[0122] C′ L - the gradient of the lift coefficient with respect to the angle of attack;

[0123] C′ D - Gradient of the drag coefficient with respect to the angle of attack.

[0124] It can be seen from formula (5) that, in addition to the vibration direction, other parameters that affect the vibration include parameters such as the angle of attack, the incoming flow velocity, the lift and drag coefficient and its gradient. When η is negative, the aerodynamic resultant force at the cross section of the blade 30 does positive work, resulting in instability. It can be seen from the expression (5) of η that the way to increase damping and improve stability can be to increase the drag coefficient, reduce the lift coefficient, and reduce the gradient of the lift and drag coefficients. In the present invention, by providing a drag-adding device on the blade 30, it is possible to increase the drag coefficient, reduce the lift coefficient, and reduce the lift and reduce the gradient of the drag coefficient at the same time, thereby achieving the purpose of increasing damping and improving blade stability.

[0125] In formula (5), C D The coefficient range of the term is larger than the coefficients of the other two terms, obviously to improve C D The most efficient way to increase the damping coefficient is D When η is large and changes little with the angle of attack, it can ensure that η is always greater than zero at any large wind speed.

[0126] The expression of formula (5) can also be used to analyze Fig.12 The stall-induced flutter model with a single vibration direction is shown in the figure. In this model, since the vibration direction of the blade section is perpendicular to the incoming flow direction, θ-φ0=π / 2. Substituting into equation (5), the part in the brackets of equation (5) can be simplified to 2(C D +C′ L ), it can be seen that when C′ L Negative and its absolute value is greater than C D When , the system is unstable. In this case, C D The coefficient of the term ranges from [2,4], which is larger than the coefficients of the other two terms, indicating that the C D The most efficient way to increase the damping coefficient is D It is larger than the coefficients of the other two terms, so it can ensure that η is always greater than zero, thereby ensuring the stability of the system.

[0127] According to the embodiment of the present disclosure, by providing a resistance device, after the airflow passes through both sides of the blade and enters the wind bag, a negative pressure is formed on the leeward side of the resistance device. Due to the pressure difference on both sides, the blade is subjected to an opposite pressure difference resistance in the vibration direction, thereby achieving the purpose of increasing C D The purpose is to more effectively increase the equivalent damping coefficient η and enhance the vibration suppression effect of the blade.

[0128] Fig.14 and Fig.15 The velocity field result of the two-dimensional CFD (Computational Fluid Dynamics) simulation of the present invention is shown as follows. The existence of the resistance device intensifies the surface flow separation between the pressure surface and the suction surface of the blade 30, making the surface velocities on both sides of the blade 30 tend to be consistent, thereby causing the pressure difference to decrease and the lift to decrease. According to formula (5), it can be determined that the damping can be increased, thereby enhancing the vibration suppression effect. At the same time, due to the obstruction of the blade resistance device, the airflow velocity of the blade resistance device on the side close to the blade 30 decreases and approaches 0, thereby forming a negative pressure on the other side, generating a large pressure difference resistance. Since the flow velocity on the side close to the blade 30 of the device at different attack angles is close to 0 and relatively stable, it shows a small resistance gradient. According to formula (5), it can be determined that the damping coefficient can be increased and the vibration suppression effect can be enhanced. The present invention has the most significant effect on increasing the drag coefficient by adopting the resistance device. At a large angle of attack, the magnitude of the drag coefficient can be increased from 0.3-0.5 to 1.5-2.0.

[0129] It is worth noting that in an actual three-dimensional scene, the equivalent stiffness distribution of the blade 30 is inversely proportional to the cube of the length from the blade root, so the most efficient way is to set the blade resistance device at the blade tip; the blade tip resistance part increases the direction of the aerodynamic force in the opposite direction of the speed, and the aerodynamic force does negative work, thereby avoiding the increase and accumulation of total energy in the system and achieving the effect of a damper.

[0130] Fig.16 and Fig.17 Based on the on-site parameters (wind speed, air density, etc.) of the disclosed embodiment, the corresponding aerodynamic data (C L ,C D ,C′ L ,C′ D ), the calculation results obtained by applying the above model. Among them, Fig.14 The figure shows the calculation result when the resistance device disclosed in the present invention is not installed, and the calculation uses basic aerodynamic data; Fig.15 The results after installing the resistance device disclosed in the present invention are shown. The modified aerodynamic data is used for calculation (relative to the basic aerodynamic data, the main difference is that the lift coefficient is reduced and the drag coefficient is increased). In the application scenario of this example, the blade vibration direction occurs near the chord direction, corresponding to the dotted box area in the figure. By observing the dotted box areas in the two figures, it can be seen that the damping coefficient is significantly improved after installing the resistance device, and is greater than 0 at all angles of attack.

[0131] According to the resistance-adding device of the present invention, the damping is increased by changing the flow on the blade surface and by increasing the drag coefficient. Thus, even at high wind speeds (for example, wind speeds greater than 20 m / s), vibration suppression by adding resistance can be achieved, the vibration suppression effect and the structural strength of the device can be ensured, and the stability problem in the blade yard and blade shutdown maintenance conditions can be solved.

[0132] Although the embodiments of the present application have been described in detail above, those skilled in the art may make various modifications and variations to the embodiments of the present application without departing from the spirit and scope of the present invention. It should be understood that, in the view of those skilled in the art, these modifications and variations will still fall within the spirit and scope of the embodiments of the present application defined by the claims.

Claims

1. A blade assembly, comprising a blade (30) and a resistance device arranged on the blade (30), characterized in that: The resistance device comprises a scooter bag (10) made of a flexible material and a strap (20) connected to the scooter bag (10), wherein the strap (20) is used to connect the scooter bag (10) to the blade (30), the scooter bag (10) has an air inlet (110), and the air inlet (110) faces the leading edge side (340) and / or the trailing edge side (330) of the blade (30), and under the action of external wind, the scooter bag (10) can be opened, thereby increasing the drag coefficient of the blade (30).

2. The blade assembly according to claim 1, characterized in that A portion of the air bag (10) is located on the pressure side (320) of the blade (30), and another portion of the air bag (10) is located on the suction side (310) of the blade (30), so that the flow velocity of the airflow flowing through the pressure side (320) and the suction side (310) respectively is reduced, thereby reducing the lift of the blade (30).

3. The blade assembly according to claim 2, characterized in that: The flexible material is in the form of a square or rectangular sheet, one end of the flexible material is located on the pressure side (320) of the blade (30), and the other end of the flexible material is located on the suction side (310) of the blade (30), and the strap (20) is connected to both sides of the flexible material located in the upward direction of the blade (30), so that the flexible material can be opened into a pocket shape under the action of external airflow.

4. The blade assembly according to claim 3, characterized in that: The binding strap (20) comprises: a cross binding strap (210) and an annular binding strap (220); two corners of the flexible material are located on the pressure side (320) of the blade (30), and the other two corners are located on the suction side (310) of the blade (30); on each side of the pressure side (320) and the suction side (310), the cross binding strap (210) brings the two corners of the flexible material closer to each other, thereby forming the air inlet (110) between the two corners of the flexible material; the annular binding strap (220) is connected to the two side edges of the middle part of the flexible material, and is wrapped around the circumference of the blade (30) to be fixed, so as to prevent the flexible material from moving in the span direction of the blade (30).

5. The blade assembly according to claim 1, characterized in that: The wind bag (10) is arranged within a range of 2m to 10m from the tip of the blade (30), and / or the wind bag (10) covers 50% to 80% of the chord width of the blade (30).

6. The blade assembly according to claim 1, characterized in that The wind-blowing bag (10) is provided with a hollow through hole (120).

7. The blade assembly according to any one of claims 1 to 6, characterized in that: The resistance adding devices are arranged in plurality and are arranged at intervals in the span direction of the blade (30).

8. The blade assembly according to claim 7, characterized in that The plurality of resistance devices include a first group of resistance devices arranged on the leading edge side (340) of the blade (30) and a second group of resistance devices arranged on the trailing edge side (330) of the blade (30).

9. The blade assembly according to claim 8, characterized in that The first group of resistance devices and the second group of resistance devices are alternately arranged in the span direction of the blade (30); and / or The number of the first group of resistance devices is less than or equal to the number of the second group of resistance devices.

10. The blade assembly according to claim 8, characterized in that The air inlet (110) of the scooter bag of at least a part of the first group of resistance devices and the air inlet (110) of the scooter bag of at least a part of the second group of resistance devices face each other.

11. The blade assembly according to claim 1, characterized in that The number of the ventilation bags (10) is 3 to 6, the ventilation bags (10) are arranged at intervals along the span direction of the blade (30), and the distance between two adjacent ventilation bags (10) is 20 cm to 50 cm; and / or The width of each of the wind bags (10) in the direction of the blades (30) is 1m-3m; and / or The flexible material is any one or more combinations of fabric or plastic cloth.

12. A wind turbine generator set, characterized in that: include: A blade assembly as claimed in any one of claims 1 to 11.

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