Stall detection device, blade assembly and wind generating set

Abstract

The invention provides a stall detection device, a blade assembly and a wind generating set, and the stall detection device comprises a supporting column which is used for being installed on the surface of a blade; the first end of the connecting rod is rotatably connected to the supporting column; the empennage is arranged at the second end of the connecting rod; the at least two limiting stoppers are arranged on the two sides of the second end of the connecting rod respectively and are spaced from each other; the pressure sensing piece is arranged on one of the empennage and the limiting stopper, and when the empennage abuts against the limiting stopper, the pressure sensing piece can generate a pressure signal; and the signal acquisition unit is electrically connected with the pressure sensing piece and is used for acquiring the pressure signal. According to the stall detection device, the information of local stall of the blade surface airflow can be accurately obtained in real time, the response to stall is sensitive, and in the normal working state, the influence on flowing of the airflow on the blade surface is small.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbines, and particularly relates to a stall detection device for blades, a blade assembly including the stall detection device, and a wind power generating set. Background Art

[0002] During the operation of a wind power generating set, due to reasons such as the external operating environment conditions, problems existing in the blade airfoil itself, blade surface contamination or icing, etc., blade stall may occur. When the blade is in a stalled state, the airflow attached to the surface within a partial range of the blade separates from the blade surface, the lift of the blade drops sharply, and the drag increases, resulting in insufficient power output of the blade and affecting the output power of the wind power generating set. When the wind power generating set operates in a stalled state, it will also change the loads and aerodynamic characteristics of the blades of the wind power generating set, making the vibration of the whole machine larger, causing the ultimate loads and fatigue loads of the unit components to increase, and even causing blade fracture, seriously affecting the safe and stable operation of the wind power generating set. Therefore, it is necessary to detect the stalled state of the blade surface to adjust the pitch angle of the blade or the yaw angle of the unit according to the detection results.

[0003] In the prior art, the methods for judging the flow state on the blade surface include the surface silk thread observation method, that is, sticking wool on the blade surface, observing the state of the wool by using a zoom camera or a drone, and using the two states of the wool adhering or being blown up to characterize whether the airflow separation occurs on the corresponding position surface of the blade. However, this detection method cannot obtain detection signals in real time on the one hand, and the detection results are not accurate enough on the other hand, especially being greatly affected by weather and visibility.

[0004] Therefore, a detection device that can accurately and real-time obtain the stalled state of the blade is needed. Summary of the Invention

[0005] The purpose of the present invention is to provide a stall detection device, a blade assembly including the stall detection device, and a wind power generating set to judge the airflow separation situation on the blade surface in real time and accurately, so as to accurately judge whether local stall appears on the blade surface.

[0006] To achieve the above object, the present invention provides a stall detection device for being installed on a blade of a wind turbine generator. The stall detection device includes: a support column for being installed on the surface of the blade; a connecting rod, a first end of the connecting rod being rotatably connected to the support column; a tail fin, the tail fin being disposed at a second end of the connecting rod; a stopper, there being two stoppers respectively disposed on both sides of the second end of the connecting rod and spaced apart from each other; a pressure sensing member disposed on one of the tail fin and the stopper, the tail fin being able to swing around the support column in the span direction of the blade according to the local stall state of the blade surface and abut against the stopper, so that the pressure sensing member can generate a pressure signal indicating the stall state of the blade; and a signal acquisition unit electrically connected to the pressure sensing member for acquiring the pressure signal.

[0007] According to an aspect of the present invention, the stall detection device further includes a counterweight portion, the counterweight portion being rotatably connected to the support column, and the first end of the connecting rod being fixedly connected to the counterweight portion.

[0008] According to an aspect of the present invention, a first end of the counterweight portion is a windward surface and is formed as a streamlined flow guiding surface, and the first end of the connecting rod is connected to a second end opposite to the counterweight portion.

[0009] According to an aspect of the present invention, the first end of the counterweight portion is formed as an ellipse, and a major axis of the ellipse is disposed along the extending direction of the connecting rod.

[0010] According to an aspect of the present invention, the support column is formed with a hollow inner cavity, and the signal acquisition unit is installed in the hollow inner cavity.

[0011] According to an aspect of the present invention, the stall detection device further includes a base, the base being sheet-shaped for being installed on the surface of the blade, and both the support column and the stopper are installed on the base.

[0012] According to an aspect of the present invention, the base has a central reference line, the support column is disposed on the central reference line, and the stoppers are symmetrically arranged with respect to the central reference line.

[0013] According to an aspect of the present invention, the tail fin is located in a vertical plane formed by the support column and the connecting rod.

[0014] According to an aspect of the present invention, the stoppers are symmetrically arranged with respect to the support column.

[0015] According to an aspect of the present invention, a rotation angle of the connecting rod between the two stoppers is ±15°.

[0016] According to one aspect of the present invention, the height of the stopper is 7 mm - 13 mm, and the distance between the lower edge of the fin and the base is 5 mm - 10 mm.

[0017] According to one aspect of the present invention, the pressure sensing member is a pressure sensor or a strain sensor, which is arranged on the fin. The connecting rod is a hollow rod, and the pressure sensing member is connected to the signal acquisition unit through a signal line.

[0018] According to another aspect of the present invention, there is provided a blade assembly, which includes a blade and the stall detection device as described above mounted on the blade.

[0019] According to another aspect of the present invention, the stall detection device is mounted along the chord direction of the blade, and the stoppers are symmetrically arranged with respect to the chord direction of the blade.

[0020] According to still another aspect of the present invention, there is provided a wind turbine generator set, which includes the blade assembly as described above.

[0021] The stall detection device of the present application can obtain information on local stall of the airflow on the blade surface in real time and accurately, is sensitive to stall, and has little influence on the airflow on the blade surface under normal working conditions. Description of the Drawings

[0022] Through the description with reference to the drawings which exemplarily show an example below, the above and other objects and features of the present invention will become clearer, wherein:

[0023] Figure 1 is a side view of the stall detection device according to an embodiment of the present invention.

[0024] Figure 2 is a top view of the stall detection device according to an embodiment of the present invention.

[0025] Figure 3 is a schematic diagram of the stall detection device mounted on the blade surface according to an embodiment of the present invention.

[0026] Figure 4 is a schematic diagram of the forces acting on the stall detection device according to an embodiment of the present invention. Detailed Description of the Invention

[0027] The following specific embodiments are provided to assist the reader in obtaining a comprehensive understanding of the methods, devices, and / or systems described herein. However, after understanding the disclosure of the present application, various changes, modifications, and equivalents of the methods, devices, and / or systems described herein will be apparent. For example, the order of operations described herein is merely illustrative and is not limited to those set forth herein, but rather may be changed as will be apparent after understanding the disclosure of the present application, except for operations that must occur in a specific order. In addition, descriptions of features known in the art may be omitted for greater clarity and conciseness.

[0028] The features described herein may be implemented in different forms and should not be construed as limited to the examples described herein. Instead, the examples described herein are provided only to illustrate some of the many possible ways of implementing the methods, devices, and / or systems described herein, which will be apparent after understanding the disclosure of the present application. As used herein, the term "and / or" includes any one of the associated listed items and any combination of any two or more thereof.

[0029] Embodiments of the present invention provide a stall detection device for mounting on the surface of a blade to detect the stall state of the blade and timely and accurately obtain whether the airflow on the surface of the blade is separated. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0030] Figure 1 and Figure 2 are respectively a side view and a top view of the stall detection device according to an embodiment of the present invention. Figure 3 is a schematic diagram of the stall detection device according to an embodiment of the present invention mounted on the surface of a blade.

[0031] As Figure 1 and Figure 2 shown, the stall detection device according to an embodiment of the present invention includes a support column 10, a connecting rod 20, a tail fin 30, a limiter 40, a pressure sensing member, and a signal acquisition unit 50.

[0032] The lower end of the support column 10 is used to support and connect to the surface of the blade 80. The first end of the connecting rod 20 is rotatably connected to the upper end of the support column 10. The second end of the connecting rod 20 extends in a direction away from the support column 10. The tail fin 30 is provided at the second end of the connecting rod 20. There are at least two limiters 40, which are respectively arranged on both sides of the second end of the connecting rod 20. The pressure detection member is provided on one of the tail fin 30 and the limiter 40. For example, the pressure detection member is a pressure sensor, such as a strain type pressure sensor. The tail fin 30 can swing around the support column 10 in the span direction of the blade correspondingly according to the local stall state of the blade surface and abut against the limiter 40, so that the pressure sensing member can generate a pressure signal indicating the stall state of the blade. Specifically, when the second end of the connecting rod 20 swings around the support column 10 and abuts against the limiter 40 and is squeezed, the pressure detection member can generate a pressure signal. The signal acquisition unit 50 is connected to the pressure detection member to acquire the pressure signal and transmit the acquired pressure signal, for example, send it to an external controller, so as to judge the stall state of the blade. As an example, the signal acquisition unit 50 can send the pressure signal to the control unit of the wind turbine by wired or wireless means.

[0033] As Figure 3 shown, when the stall detection device according to the embodiment of the present invention is installed on the surface of the blade 80, the support column 10 is arranged along a direction perpendicular to the surface of the blade 80, the connecting rod 20 is arranged along the chord direction of the blade, the support column 10 faces the leading edge side of the blade, and the tail fin 30 faces the trailing edge side of the blade. Therefore, the first end of the connecting rod 20 can also be called the front end of the connecting rod 20, and the second end of the connecting rod 20 can also be called the rear end of the connecting rod 20.

[0034] The tail fin 30 is sheet-shaped, and the surface of the tail fin 30 is parallel to the extending direction of the connecting rod 20. When installed on the blade surface, the tail fin 30 extends along a direction perpendicular to the surface of the blade, or is inclined at a certain angle with respect to the blade surface. The surface of the tail fin 30 is parallel to the chord direction of the blade 80 to minimize the influence on the airflow on the blade surface as much as possible. The tail fin 30 can be a single fin, or can include two fins and extend to the upper side and the lower side of the connecting rod 20. By arranging fins on both the upper side and the lower side of the connecting rod 20, the force balance of the connecting rod 20 can be ensured, and the rear end of the connecting rod 20 can be prevented from being subjected to torque while being subjected to bending moment. The pressure detection member can be arranged at the lower part of the tail fin 30 to ensure that it can abut against the limiter 40, be deformed under pressure, and thus generate a pressure signal.

[0035] The tail fin 30 can be made of materials such as plastic sheets and resin sheets, and has certain rigidity and elastic deformation ability. It can not only support and install the pressure detection component, but also deform when abutting against the stopper 40. The pressure sensor (for example, a strain gauge) can be attached to the surface of the tail fin, embedded in the surface of the tail fin 30, or embedded inside the tail fin 30.

[0036] The stoppers 40 are installed on the left and right sides of the tail fin 30 to limit the swinging range of the tail fin 30 around the support column 10. When the wind turbine is operating normally, the airflow on the blade is in a relatively stable streamline shape, and the tail fin 30 remains in a stable position between the two stoppers 40, or swings slightly, but does not collide with the stoppers 40. When the airflow separation occurs at the position of the stall detection device on the blade surface, the tail fin 30 will swing significantly, so as to touch and abut against the stopper 40. When the tail fin 30 swings and contacts the stopper 40, the pressure sensing component will deform under extrusion, thereby generating pressure and deformation signals, and the pressure and deformation signals are collected, stored and transmitted to the controller of the wind turbine by the signal acquisition unit 50. As an example, the height of the stopper 40 is about 10 mm, and the distance between the lower end of the tail fin 30 and the installation surface is 5 mm, so as to ensure that the tail fin 30 can swing within the range restricted by the stopper 40, and the bottom of the tail fin 30 can generate pressure and deformation when contacting the stopper 40.

[0037] As Figure 2 shown, relative to the rotation center, the included angle α between the connecting rod 20 and the stopper 40 can be 10° - 25°, for example, 15°. The range of the included angle α determines the response speed of the stall detection device. The larger the included angle α, the longer the swinging path of the tail fin 30 between the two stoppers 40, the more time is required, and the slower the response speed will be.

[0038] The support column 10 can be a hollow column body, and the signal acquisition unit 50 can be installed in the inner cavity of the support column 10. By installing the signal acquisition unit 50 inside the support column 10, on the one hand, it avoids occupying extra space and makes the structure of the device more compact. On the other hand, it can isolate the signal acquisition unit 50 from the outside world, avoid the influence of external wind, frost, rain and snow, and extend the service life.

[0039] The connecting rod 20 is a slender rod, which provides a lever arm for the aerodynamic force acting on the tail fin. By increasing or decreasing the length of the connecting rod 20, the generated torque can be amplified or reduced. As an example, the connecting rod 20 can also be a hollow rod. In the case where the pressure detection component is arranged on the tail fin 30, the signal wire can pass through the inside of the connecting rod 20 to electrically connect the pressure detection component and the signal acquisition unit 50. Thus, the electronic components are arranged in a closed space to avoid the corrosion and aging of the signal wire in the external environment.

[0040] The stall detection device according to an embodiment of the present invention may further include a counterweight portion 60. The counterweight portion 60 is connected to the upper end of the support column 10 through a rotating shaft 12 and can rotate around the rotating shaft 12. The first end (front end) of the counterweight portion 60 is the windward surface, and the first end (front end) of the connecting rod 20 is connected to the second end (rear end) of the counterweight portion 60. When installed on the surface of the blade 80, the counterweight portion 60 is located on the side facing the leading edge of the blade. By providing the counterweight portion 60, a certain moment of inertia is provided to prevent the tail fin 30 from rotating due to forces or torques other than the airflow, thus avoiding interference with the accuracy of signal acquisition.

[0041] In addition, by providing the counterweight portion 60, the center of gravity of the stall detection device can be made as close as possible to the support column 10 or coincide with the support column 10, preventing the rear end of the connecting rod 20 from sagging, twisting, or warping relative to the support column 10, and improving the stability and service life of the stall detection device.

[0042] To reduce the influence of the stall detection device on the airflow on the blade surface, the front end of the counterweight portion 60 is formed into a streamlined guide portion, reducing the area of frontal collision with the airflow. On the one hand, the wind resistance received by the stall detection device is reduced, thus preventing the support column 10 from bearing a bending moment due to wind resistance and causing detachment from the blade surface. On the other hand, through the guiding action of the guide portion, the airflow smoothly flows along the outer peripheral surface of the counterweight portion 60, reducing the influence on the airflow on the blade surface.

[0043] The front-end guide portion of the counterweight portion 60 can be formed into an ellipse, and the major axis of the ellipse is in the same direction as the extension direction of the connecting rod 20. Similarly, to reduce wind resistance and the influence on the airflow on the blade surface, the outer periphery of the support column 10 is also formed into a streamlined shape. For example, the support column 10 is a cylinder or an elliptical cylinder.

[0044] To facilitate the installation of the stall detection device on the surface of the blade, the stall detection device according to an embodiment of the present invention may further include a mounting base 70. The support column 10 and the limiter 40 are both installed on the mounting base 70 to form an integral body, so that the stall detection device can be installed on the blade as a whole, reducing the trouble of positioning the support column and the limiter during the installation process. The mounting base 70 can be sheet-shaped, facilitating conformal fitting with the surface of the blade. Structural adhesive can be used to bond the mounting base 70 to the blade.

[0045] The base 70 can be formed into a circular thin sheet or an oval sheet. The connecting rod 20 is arranged along the long axis direction of the ellipse, and the limiters 40 are located at both ends of the short axis of the ellipse. A positioning line can be provided on the base 70, which is roughly located in the middle of the base 70. The support column 10 is located on the positioning line, and the limiters 40 on both sides are symmetrically arranged with respect to the positioning line. When installing the stall detection device on the blade, the positioning line on the base 70 can be aligned with the chord direction of the blade, and the base 70 can be pasted onto the blade surface. The installation process is simple, and the pasting method is more convenient, avoiding damage to the structure of the blade.

[0046] The outer contour of the base 70 forms a circle or an ellipse, which can reduce the influence of the edge corners on the airflow on the blade surface. In addition, chamfers can be formed on the edges of the base 70 to enable a smooth transition between the upper surface of the base 70 and the blade surface, reducing the influence on the airflow on the blade surface.

[0047] Since the separation of the airflow from the blade surface mainly occurs near the trailing edge of the blade when the blade stalls. Therefore, the stall detection device according to the embodiment of the present invention can be installed near the trailing edge of the blade. Figure 3 The schematic diagram shows the installation of the stall detection device according to the embodiment of the present invention on the surface of the blade 80. As Figure 3 shown, the stall detection device is installed along the chord direction of the blade 80, and the tail wing 30 faces the trailing edge of the blade. In the spanwise direction of the blade 80, multiple stall detection devices can be installed to detect the airflow flow conditions at multiple positions of the blade. By a single stall detection device, it can be determined whether the blade has a local stall, and by multiple stall detection devices, it can be further determined whether the blade has an overall stall.

[0048] Under the normal operating state of the unit, the flow direction on the blade surface is along the chord direction. Therefore, the direction of the tail wing 30 also points along the chord direction and remains stable. Since the guiding part is based on a streamline guiding design, under the normal operating state, this stall detection device has no obvious influence on the flow on the blade surface.

[0049] When local stall occurs on the blade surface, the local area on the blade surface shows turbulence, and the flow direction no longer follows the chord direction but is in any direction. At the same time, the airflow that no longer adheres to the blade surface is affected by the centrifugal force generated by the rotation of the impeller, generating an obvious velocity component along the spanwise direction of the blade and pointing outward, causing the tail wing 30 to swing left and right, but being restricted between the limiters 40 on both sides, alternately colliding with the limiters 40 on the left and right sides. The pressure detection part generates pressure and strain, and this change can be converted into an electrical signal, which is collected, stored, and transmitted by the signal acquisition unit 50.

[0050] The stall detection device according to an embodiment of the present invention, the support column 10, the connecting rod 20, the tail wing 30, the limiter 40, and the base 70 can be made of materials such as plastic, rubber, resin, etc. For example, made of PVC material, it has the advantages of being easy to manufacture, low cost, corrosion resistance, etc.

[0051] Figure 4 The force diagram of the stall detection device is shown. As Figure 4 shown, when the airflow on the blade surface separates, the tail wing no longer points to the flow direction, that is, forms a certain angle β with the flow direction. The lift L and drag D induced by the angle β will respectively generate torques M that cause the tail wing to rotate until torque balance is reached, that is, it points to the flow direction. Before reaching torque balance, the tail wing 30 collides with the limiter 40, so that under the action of the torque, the limiter 40 is squeezed, and thus the pressure detection component provided on the tail wing 30 generates pressure and strain.

[0052] According to the stall detection device of the present invention, during the operation stage of the unit, it can effectively and real-time detect the stall state of the key cross-section of the blade, and transmit this stall state as an input to the control module of the wind turbine generator. By adjusting the pitch angle of the blade through the control module, etc., it can effectively reduce or avoid problems such as the right shift and collapse of the power curve caused by stall, and vibration problems caused by stall induction, etc.

[0053] In addition, during the blade development and testing stage, the stall detection device can also be installed on the blade surface to detect, debug, and modify the aerodynamic performance of the blade, minimizing the constraints on the aerodynamic shape design caused by blade stall to the greatest extent, so that the designed aerodynamic shape can better meet the design requirements of increasing power and reducing load.

[0054] According to the stall detection device of the present invention, based on the change in the airflow state on the blade surface during local stall, by using the characteristic that the separated airflow on the blade surface during stall generates a velocity component along the span direction under the action of the centrifugal force generated by rotation, stall identification and judgment are carried out, and the information on local stall of the airflow on the blade surface can be obtained in real time and accurately. It is sensitive to stall and has little impact on the airflow on the blade surface under normal working conditions.

[0055] Although the embodiments of the present invention have been described in detail above, those skilled in the art can make various modifications and variations to the embodiments of the present invention 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 invention defined by the claims.

Claims

1. A stall detection device for installation on a blade of a wind turbine generator, characterized in that, The stall detection device includes: A support column (10) for being mounted on the surface of the blade; A connecting rod (20), with the first end of the connecting rod (20) rotatably connected to the support column (10); A tail wing (30) provided at the second end of the connecting rod (20); Limiters (40), with at least two limiters (40) respectively arranged on both sides of the second end of the connecting rod (20) and spaced apart from each other; A pressure sensing member provided on one of the tail wing (30) and the limiter (40). The tail wing (30) can swing around the support column (10) in the span direction of the blade according to the local stall state on the surface of the blade and abut against the limiter (40), so that the pressure sensing member can generate a pressure signal indicating the stall state of the blade; A signal acquisition unit (50) electrically connected to the pressure sensing member for acquiring the pressure signal.

2. The stall detection device according to claim 1, wherein The stall detection device further includes a counterweight portion (60). The counterweight portion (60) is rotatably connected to the support column (10), and the first end of the connecting rod (20) is fixedly connected to the counterweight portion (60).

3. The stall detection device according to claim 2, wherein The first end of the counterweight portion (60) is the windward surface and is formed into a streamlined guiding surface, and the first end of the connecting rod (20) is connected to the opposite second end of the counterweight portion (60).

4. The stall detection device according to claim 3, wherein The first end of the counterweight portion (60) is formed into an ellipse, and the major axis of the ellipse is arranged along the extending direction of the connecting rod (20).

5. The stall detection device according to claim 1, wherein The support column (10) is formed with a hollow inner cavity, and the signal acquisition unit (50) is installed in the hollow inner cavity.

6. The stall detection device according to claim 1, wherein The stall detection device further includes a base (70). The base (70) is in a sheet shape for being mounted on the surface of the blade, and both the support column (10) and the limiter (40) are mounted on the base (70).

7. The stall detection device according to claim 6, characterized in that The base (70) has a central reference line. The support column (10) is arranged on the central reference line, and the limiters (40) are symmetrically arranged with respect to the central reference line.

8. The stall detection device according to claim 1, wherein The tail wing (30) is located in the vertical plane formed by the support column (10) and the connecting rod (20).

9. The stall detection device according to claim 1, wherein, The limiters are symmetrically arranged with respect to the support column.

10. The stall detection device according to claim 9, characterized in that, The rotation angle of the connecting rod (20) between the two limiters (40) is ±15°.

11. The stall detection device according to claim 6, characterized in that, The height of the limiter (40) is 7 mm - 13 mm, and the distance between the lower edge of the tail wing (30) and the base is 5 mm - 10 mm.

12. The stall detection device according to claim 5, characterized in that, The pressure sensing member is a strain type pressure sensor provided on the tail wing (30). The connecting rod (20) is a hollow rod, and the pressure sensing member is connected to the signal acquisition unit (50) through a signal line.

13. A blade assembly, characterized in that, The blade assembly includes a blade and the stall detection device as described in any one of claims 1 - 12 mounted on the blade.

14. The blade assembly according to claim 13, wherein, The stall detection device is mounted along the chord direction of the blade, and the limiters (40) are symmetrically arranged with respect to the chord direction of the blade.

15. A wind power generating set, characterized in that, The wind turbine generator set includes the blade assembly as described in claim 13 or 14.

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