Wind turbine blade liquid damper, pre-manufacturing method and wind turbine blade

Abstract

The application discloses a wind power blade liquid damper, a prefabrication method and a wind power blade. The liquid damper comprises an elongated pipe and damping liquid. The elongated pipe is arranged in parallel on the SS inner surface and the PS inner surface of the wind power blade at a preset interval, is located at the wind power blade tip, is arranged along the airfoil contour line of the wind power blade, and is connected to the leading edge and the trailing edge of the wind power blade at two ends. The central axis of each elongated pipe is perpendicular to the pitch shaft of the wind power blade. The damping liquid is filled in the elongated pipe at a preset volume filling rate, so that the damping liquid is constrained in the elongated pipe and flows back and forth along the airfoil contour line of the wind power blade. The centrifugal force direction of the blade is always perpendicular to the movement track of the damping liquid. The liquid turbulent flow is generated by bending the elongated pipe to absorb vibration energy, the first-order pendulum vibration of the wind power blade can be effectively inhibited, and the liquid damper can meet the maintenance-free characteristic requirement in the service life.

Description

Technical Field

[0001] This invention relates to the technical field of wind turbine blade dampers, and in particular to a liquid damper for wind turbine blades, a prefabrication method, and a wind turbine blade. Background Technology

[0002] The manufacturing technology of wind turbine power generation equipment is advancing rapidly. The single-unit capacity of the equipment has exceeded 20MW, the blade length exceeds 100 meters, and the hub height of the turbine has exceeded 150m, etc., and the cost of the equipment is also increasing. Faced with complex wind resources and conditions, the risk of blade damage is also increasing. Wind turbine blades are slender shell structures that are very flexible. In complex and variable strong gusts, vibration problems are very prominent, especially the first-order mode vibration in the wobbling direction. If the vibration is not effectively damped and suppressed, it will seriously affect the fatigue life of the blade, and resonance can even lead to the catastrophic failure of the blade.

[0003] Among existing tuned mass damping technologies, there are electroturbulence dampers and liquid mass dampers. Electroturbulence damping technology suffers from high costs and issues with lifespan and reliability, making it difficult to achieve the desired performance. Liquid mass damping, on the other hand, inherently possesses excellent reliability properties, thus becoming a focus of research. Existing liquid mass dampers have been applied in bridges and high-rise buildings, but their application in blades is not yet mature. This is because the damping mechanism of liquid mass dampers used in buildings cannot be fully utilized under blade operating conditions. For example, the patent application No. 99811451.0, "Wind Turbine Blade with U-shaped Vibration Damping Device," and the patent application No. 201610959925.8, "A Circular Tube Liquid Damper for Reducing Edge Vibration of Wind Turbine Blades," share a common drawback. On the one hand, because the U-shaped and O-shaped liquid tubes described in the patents have their tube planes parallel to the blade pitch axis, under the enormous centrifugal force during impeller rotation, the depth of the tube in the direction of the centrifugal force is too large. The enormous centrifugal force cannot generate a liquid dynamic pressure difference, and the damping mechanism of the liquid damper is basically ineffective due to the presence of centrifugal force, thus failing to play a damping role. On the other hand, during the hoisting stage or when the machine is stopped, the phase position and blade attitude on the impeller are random. When the blade axis is horizontal, the U-shaped and O-shaped dampers will lose their damping mechanism and fail, and only when the blade is vertically pointing towards the ground will they have a relatively ideal damping effect. This means that its damping mechanism is to use the dynamic pressure difference of the sloshing liquid to tune the damping. These liquid dampers have not been able to combine the working state of the blades with the liquid damping mechanism well, so their practicality is poor. Summary of the Invention

[0004] The primary objective of this invention is to address the shortcomings of existing technologies by providing a liquid damper for wind turbine blades. This damper achieves high efficiency and maintenance-free operation through a slender tube liquid turbulence damping mechanism. By using a serpentine tube design to create liquid turbulence to absorb vibration energy, it effectively suppresses the first-order oscillation of wind turbine blades and meets the requirement of maintenance-free operation throughout the lifespan of the liquid damper.

[0005] A second objective of this invention is to provide a method for prefabricating a liquid damper for wind turbine blades.

[0006] A third objective of this invention is to provide a wind turbine blade.

[0007] The first objective of this invention is achieved through the following technical solution: a liquid damper for wind turbine blades, comprising elongated tubes and damping fluid; the elongated tubes are arranged in parallel at predetermined intervals on the inner surfaces of the SS and PS of the wind turbine blade, and located at the tip of the wind turbine blade; each elongated tube is arranged along the airfoil profile of the wind turbine blade, and both ends of each elongated tube are connected to the leading edge and trailing edge of the wind turbine blade, respectively; the central axis of each elongated tube is perpendicular to the pitch shaft of the wind turbine blade; the damping fluid is filled inside the elongated tubes at a predetermined volumetric filling rate, so that the damping fluid is constrained in the elongated tubes and flows back and forth along the airfoil profile of the wind turbine blade, and the direction of the centrifugal force of the blade is always perpendicular to the movement trajectory of the damping fluid.

[0008] Furthermore, the slender tubing is a serpentine thermoplastic tube.

[0009] Furthermore, the maximum diameter of the cross-section of the slender tube is less than 50 mm, and the cross-section of the slender tube is one of a circle, an ellipse, or a rectangle.

[0010] Furthermore, multiple slender tubes on the same PS inner surface or the same SS inner surface are arranged at intervals of 0.1m-1m along the spanwise direction of the wind turbine blade, and are located at a position at least 2 / 3 of the blade length away from the blade root.

[0011] Furthermore, the damping fluid is one of silicone oil, water, or a saturated aqueous solution of calcium chloride, and the volume filling rate of the damping fluid is 10%–30%.

[0012] Furthermore, the total mass of the damping fluid is 0.1%–1% of the total mass of the wind turbine blade.

[0013] The second objective of this invention is achieved through the following technical solution: a prefabrication method for the above-mentioned liquid damper for wind turbine blades, comprising the following steps:

[0014] S1. First, heat-bend the plastic tube into a serpentine bend, and then open a damping fluid injection valve on the serpentine bend.

[0015] S2. The damper mounting base plate with flange edge is manufactured by hand lay-up fiberglass. The flange edge of the damper mounting base plate is consistent with the PS or SS profile of the wind turbine blade mounting section. The liquid damper and the blade PS or SS skin are bonded together by relying on this flange edge.

[0016] S3. The hand lay-up fiberglass fixed serpentine bend is placed on the damper mounting base plate. The plane of the serpentine bend is perpendicular to the flange edge of the damper mounting base plate. One end of the serpentine bend is at the leading edge of the blade, and the other end is at the trailing edge of the blade.

[0017] S4. Before use, remove the release cloth from the flange edge, install it on the wind turbine blade, and then add damping fluid.

[0018] The third objective of this invention is achieved through the following technical solution: a wind turbine blade, wherein the wind turbine blade has the aforementioned wind turbine blade liquid damper built in.

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0020] 1. The liquid damper of this invention employs a highly efficient liquid turbulence damping mechanism, featuring a simple structure, reliable performance, long lifespan, and maintenance-free operation. Its use of a damper central axis structure perpendicular to the centrifugal force direction and a slender structure ensures excellent damping performance of the blades in any orientation during operation and shutdown. The adoption of slender tubes, low liquid filling ratio, long stroke, and bending stroke extension technologies significantly improves damping efficiency.

[0021] 2. The damper of the present invention is maintenance-free, so the damper can be arranged inside the blade and placed as close as possible to the blade tip. Therefore, the applied liquid mass is minimized, the cost is minimized, and the first-order vibration of the blade can be effectively suppressed to achieve high-efficiency damping. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a wind turbine blade with a serpentine thermoplastic tube installed.

[0023] Figure 2 A schematic diagram of the mounting plate for an L-shaped cross-section damper. Detailed Implementation

[0024] The present invention will be further described below with reference to specific embodiments.

[0025] Example 1

[0026] See Figure 1 As shown, the wind turbine blade liquid damper provided in this embodiment includes a slender tube 1 and a damping fluid (not shown in the figure);

[0027] The slender tube 1 is a serpentine thermoplastic tube, installed inside the wind turbine blade via a damper mounting base plate 2 with an L-shaped cross-section and flange. Three slender tubes 1 are spaced 0.1m apart and arranged side-by-side on the inner SS surface 3 and the inner PS surface (not shown in the figure) of the wind turbine blade. The slender tubes on the PS and SS inner surfaces are arranged in pairs (not shown in the figure). The slender tubes 1 are located at the tip section of the wind turbine blade. Each slender tube 1 is positioned along the airfoil profile 4 of the blade, and both ends of each slender tube 1 are connected to the leading edge 5 and trailing edge 6 of the wind turbine blade, respectively. Each slender tube 1 has its central axis perpendicular to the pitch shaft 7 of the wind turbine blade. The damping fluid (not shown in the figure) is filled inside the slender tube at a preset volumetric filling ratio, causing the damping fluid to flow back and forth along the airfoil profile 4 within the slender tube 1. The fluid absorbs kinetic energy and reduces vibration through the turbulent flow generated by the bending of the slender tube 1. The centrifugal force direction 8 of the blade is always perpendicular to the damping fluid's trajectory 9. During impeller rotation, the liquid damper can provide good damping even when it is in any position within 360 degrees of the vertical plane. The total mass of the damping fluid is 0.1%–1% of the total mass of the wind turbine blade; the damping fluid is one of silicone oil, water, or a saturated aqueous solution of calcium chloride; and the volumetric filling ratio of the damping fluid is 10%–30%.

[0028] Liquid dampers need to be environmentally adaptable, operating normally in cold environments within a temperature range of -40℃ to +50℃. Therefore, silicone oil or specific electrolyte solutions can achieve this. Silicone oil is a more ideal material, and different molecular weight silicone oils can be selected based on the design viscosity. A saturated aqueous solution of calcium chloride can also be used, but this electrolyte solution has corrosive and lightning strike characteristics as side effects. However, the disadvantage of silicone oil is its higher cost compared to calcium chloride solution. If calcium chloride solution is used, local lightning protection must be considered. Therefore, the damping fluid can be silicone oil, water, or a saturated aqueous solution of calcium chloride, selected according to the wind turbine's operating environment. In cold regions, silicone oil or a saturated aqueous solution of calcium chloride is used, while in warm and tropical regions, water is sufficient. Using inexpensive water eliminates the need to consider lightning protection.

[0029] Example 2

[0030] Unlike Embodiment 1, the slender tube 1 has three slender tubes spaced 1m apart and arranged in parallel on the inner surface of the SS and the inner surface of the PS of the wind turbine blade, with the slender tubes on the inner surface of PS and the inner surface of SS arranged in pairs.

[0031] Example 3

[0032] See Figure 2As shown, this embodiment provides a structure of a damper mounting base plate 2 with an L-shaped cross-section and a flange. The curvature 2011 of the flange edge 201 of the damper mounting base plate is consistent with the curvature of the airfoil profile line 4 of the SS or PS surface of the wind turbine blade. It can be made using a template. The plane 202 for installing the serpentine thermoplastic tube is perpendicular to the flange edge 201. 203 is the leading edge point of the damper mounting base plate, 204 is the trailing edge point of the damper mounting base plate, and 205 is the chord of the damper mounting base plate. The damper mounting base plate can be prefabricated using a mold, preferably made of fiberglass, and hand lay-up molded.

[0033] A method for prefabricating a liquid damper for wind turbine blades according to Embodiment 1 or 2 includes the following steps:

[0034] S1. First, heat-bend the plastic tube into a serpentine bend, and then open a damping fluid injection valve on the serpentine bend.

[0035] S2. The damper mounting base plate with flange edge is manufactured by hand lay-up fiberglass. The flange edge of the damper mounting base plate is consistent with the PS or SS profile of the wind turbine blade mounting section. The liquid damper and the blade PS or SS skin are bonded together by relying on this flange edge.

[0036] S3. The hand lay-up fiberglass fixed serpentine bend is placed on the damper mounting base plate. The plane of the serpentine bend is perpendicular to the flange edge of the damper mounting base plate. One end of the serpentine bend is at the leading edge of the blade, and the other end is at the trailing edge of the blade.

[0037] S4. Before use, remove the release cloth from the flange edge, install it on the wind turbine blade, and then add damping fluid.

[0038] Example 4

[0039] This embodiment provides a wind turbine blade, which incorporates a liquid damper as described in Embodiment 1 or 2. There is at least one liquid damper located at least 2 / 3 of the blade length from the blade root. The central axis of each liquid damper is perpendicular to the blade's pitch shaft. The two ends of the liquid damper connect to the leading and trailing edges of the blade, suppressing vibrations in the blade's oscillation direction. Planar curved dampers are installed inside the blade along the inner PS and SS surfaces, preferably in a paired arrangement. Multiple liquid dampers on the same PS or SS surface are preferably spaced 0.1m-1m apart along the blade's spanwise direction. The total mass of damping fluid in the wind turbine blade is 0.1%-1% of the total blade mass.

[0040] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Therefore, any changes made in accordance with the shape and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for prefabricating a liquid damper for wind turbine blades, characterized in that: The wind turbine blade liquid damper includes slender tubes and damping fluid. The slender tubes are arranged in parallel at preset intervals on the inner surfaces of the SS and PS of the wind turbine blade and are located at the tip of the wind turbine blade. Each slender tube is arranged along the airfoil profile of the wind turbine blade, and both ends of each slender tube are connected to the leading edge and trailing edge of the wind turbine blade, respectively. The central axis of each slender tube is perpendicular to the pitch shaft of the wind turbine blade. The damping fluid is filled into the interior of the slender tubes at a preset volume filling rate, so that the damping fluid is constrained in the slender tubes and flows back and forth along the airfoil profile of the wind turbine blade. The direction of the centrifugal force of the blade is always perpendicular to the movement trajectory of the damping fluid. The prefabrication method includes the following steps: S1. First, heat-bend the plastic tube into a serpentine bend, and then open a damping fluid injection valve on the serpentine bend. S2. The damper mounting base plate with flange edge is manufactured by hand lay-up fiberglass. The flange edge of the damper mounting base plate is consistent with the PS or SS profile of the wind turbine blade mounting section. The liquid damper and the blade PS or SS skin are bonded together by relying on this flange edge. S3. The hand lay-up fiberglass fixed serpentine bend is placed on the damper mounting base plate. The plane of the serpentine bend is perpendicular to the flange edge of the damper mounting base plate. One end of the serpentine bend is at the leading edge of the blade, and the other end is at the trailing edge of the blade. S4. Before use, remove the release cloth from the flange edge, install it on the wind turbine blade, and then add damping fluid.

2. The prefabrication method of a liquid damper for wind turbine blades according to claim 1, characterized in that: The slender tubing is a serpentine thermoplastic tube.

3. The prefabrication method of a liquid damper for wind turbine blades according to claim 1, characterized in that: The maximum diameter of the slender tube is less than 50 mm, and the cross-section of the slender tube is one of a circle, an ellipse, or a rectangle.

4. The prefabrication method of a liquid damper for wind turbine blades according to claim 1, characterized in that: Multiple slender tubes are arranged at intervals of 0.1m-1m along the span of the wind turbine blade on the same PS inner surface or the same SS inner surface, and are located at a position at least 2 / 3 of the blade length away from the blade root.

5. The prefabrication method of a liquid damper for wind turbine blades according to claim 1, characterized in that: The damping fluid is one of silicone oil, water, or a saturated aqueous solution of calcium chloride, and the volume filling rate of the damping fluid is 10%–30%.

6. The prefabrication method of a liquid damper for wind turbine blades according to claim 1, characterized in that: The total mass of the damping fluid is 0.1% to 1% of the total mass of the wind turbine blade.

7. A wind turbine blade, characterized in that, The wind turbine blade has a built-in wind turbine blade liquid damper prepared by the prefabrication method according to any one of claims 1 to 6.

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