Free surface enhanced shaking liquid damper for vibration reduction of floating type wind driven generator

Abstract

The utility model provides a free surface enhancement type shaking liquid damper for vibration reduction of a floating type wind driven generator, which comprises a damper cavity which is a closed cavity and is filled with liquid; the solid particles are used for enhancing the surface of the liquid so as to inhibit the breaking phenomenon of the liquid during large-amplitude shaking, the solid particles float on the surface of the liquid, and the density of the solid particles is smaller than that of the liquid. The free surface of liquid can be enhanced, and then the damping performance is improved.

Description

Technical Field

[0001] The utility model belongs to the field of vibration control of floating wind turbines, and in particular relates to a free surface enhanced sloshing liquid damper used for vibration reduction of floating wind turbines. Background Art

[0002] In recent years, with the rapid growth of green energy demand, wind power generation, as a clean and renewable energy form, has been continuously expanding its application scope. As the development of land wind power resources gradually approaches saturation, the development focus of the wind power industry has begun to shift to the vast ocean, promoting the rapid development of floating wind turbines. At present, the foundation types of floating wind turbines mainly include barge type, semi-submersible type, column type and tension leg type. Among them, the semi-submersible foundation has become the most widely used floating wind turbine foundation due to its significant advantages such as flexible water depth adaptability, low transportation cost and convenience for overhaul in ports. Therefore, the utility model will focus on floating wind turbines based on semi-submersibles to further promote their application and development in the field of wind power generation.

[0003] Compared with land-based wind turbines, floating wind turbines are affected by a variety of environmental factors at sea, such as wind, currents, waves, and tides, and the stress conditions are more complicated. Excessive vibration of floating wind turbines under complex load conditions will not only shorten the service life of various structural components of the unit and sensitive components inside the cabin, but also increase the operation and maintenance costs of the wind turbine. Therefore, it is particularly important to develop a vibration reduction device suitable for floating wind turbines.

[0004] Among the existing vibration reduction devices, tuned liquid damper (TLD) has attracted wide attention due to its significant advantages such as economical and practical, easy operation, strong applicability, low maintenance cost and diverse functions. However, when faced with working conditions with large structural vibration amplitude, the free liquid surface of conventional TLD is prone to breakage, resulting in its frequency detuning, which seriously weakens its vibration reduction effect. For this reason, the floating blanket-type offshore anti-sway technology of floating liquefied natural gas platform storage tanks can be used as a reference to enhance the free liquid surface of TLD, improve its vibration control effect and the robustness of control performance when the structure vibrates significantly. Summary of the invention

[0005] The purpose of the utility model is to provide a free surface enhanced slosh damper for vibration reduction of floating wind turbines, which can improve the vibration reduction performance. To achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0006] A free surface enhanced sloshing liquid damper for vibration reduction of a floating wind turbine generator, comprising:

[0007] The damper cavity 3 is a closed cavity filled with liquid 4;

[0008] The solid particles 5 are used to enhance the surface of the liquid 4 , thereby suppressing the breakage of the liquid when it is shaken greatly. The solid particles 5 float on the surface of the liquid 4 and have a density less than that of the liquid 4 .

[0009] Preferably, it also includes:

[0010] The damping mesh partition 6 is used to filter the high-order sloshing modal components of the liquid motion, and is fixed to the inner wall of the damper cavity 3, and the damper cavity 3 is a cross-shaped structure; the damping mesh partition 6 is located in the orthogonal direction of the cross;

[0011] The damping mesh partition 6 is provided with a plurality of screen grids, which allow the liquid 4 to pass through but do not allow the solid particles 5 to pass through.

[0012] Preferably, it also includes:

[0013] The output shaft of the rotating motor 7 is fixed to the bottom of the damper cavity 3 , and the housing thereof is fixed to the top of the tower body 2 of the floating wind turbine generator.

[0014] Preferably, the liquid depth h in the damper cavity 3 is:

[0015]

[0016]

[0017] Wherein, ω0-the first-order frequency of the floating wind turbine tower affected by the floating foundation;

[0018] χ-frequency ratio of the slosh damper;

[0019] ω1-the first sloshing frequency of the liquid;

[0020] L—length of the damper cavity 3.

[0021] Preferably, the number of layers of the solid particles 5 is N.

[0022] Preferably, the solid particles 5 are made of light resin material.

[0023] Compared with the prior art, the advantages of the utility model are:

[0024] 1. Enhance the free surface of the liquid: By laying lightweight tiny solid particles on the free surface of the liquid in the sloshing damper, the free surface of the liquid is enhanced, and the wave breaking phenomenon when the liquid in the sloshing damper sloshes greatly is suppressed. The damping mesh partition divides the damper cavity into different areas, so that when the rotating motor drives the sloshing damper to rotate, the lightweight solid particles in each area will not flow with each other, avoiding the situation where lightweight solid particles accumulate on one side of the damper cavity. Therefore, it can effectively improve the vibration reduction performance of the sloshing damper and enhance its performance robustness when the structure vibrates greatly.

[0025] 2. Improve the energy dissipation performance of the sloshing liquid damper: The device proposed by the utility model not only has the mutual friction energy dissipation between the liquid and the cavity, but also has the friction energy dissipation between the liquid and the solid particles, between the solid particles, and between the liquid and the damping mesh partition. Therefore, it can effectively improve the vibration reduction performance of the sloshing liquid damper.

[0026] 3. Easy to manufacture and install: The device proposed by the utility model is composed of a sloshing liquid damper cavity and a rotating motor, as well as liquid inside the liquid damper cavity, light solid particles on the liquid surface and a damping baffle. It has fewer components and is easy to install. The light solid particles can be processed and manufactured using materials with relatively mature manufacturing processes.

[0027] 4. Wide range of applications: The free surface enhanced sloshing damper proposed in the utility model is not only applicable to offshore floating wind turbines with different foundation types, but can also be applied to large onshore wind turbines and various building structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A front view schematic diagram of a wind turbine equipped with a slosh damper;

[0029] Figure 2 It is a three-dimensional schematic diagram of the structure of the slosh damper;

[0030] Figure 3 is a top view of the slosh damper;

[0031] Figure 4 is a front view of the slosh damper;

[0032] Figure 5 It is the front view of the damping net partition;

[0033] Figure 6 A set of comparative reference figures of the present utility model;

[0034] Figure 7 Side view of a floating wind turbine equipped with a slosh damper.

[0035] Among them, 1-floating wind turbine foundation structure, 2-floating wind turbine tower body, 3-sloshing liquid damper cavity, 4-liquid, 5-solid particles, 6-damping net partition, 7-rotating motor. DETAILED DESCRIPTION

[0036] The following is a more detailed description of the free surface enhanced slosh damper for floating wind turbine vibration reduction of the present invention in conjunction with the schematic diagram, wherein the preferred embodiment of the present invention is shown, and it should be understood that the present invention described herein can be modified by those skilled in the art, while still achieving the advantageous effects of the present invention. Therefore, the following description should be understood as being widely known to those skilled in the art, and not as a limitation to the present invention.

[0037] like Figures 1 to 7 , a free surface enhanced sloshing liquid damper for vibration reduction of a floating wind turbine, comprising:

[0038] The damper cavity 3 is a closed cavity of a cross-shaped structure, which is filled with liquid 4 and has a bottom fixed to the output shaft of the rotating motor 7 . The housing of the rotating motor 7 is fixed to the top of the floating wind turbine tower 2 .

[0039] The damper cavity is a cross-shaped structure, and there is no need to consider the problem of decreased vibration reduction effect caused by possible rotational movement of the liquid in the sloshing damper.

[0040] However, the external loads on the floating wind turbine may come from all directions, and the cross-shaped liquid damper only has a high damping effect in two orthogonal directions. Therefore, it is necessary to install a rotating motor 7 at the bottom of the sloshing liquid damper, which can be rotated according to the force conditions of the wind turbine tower body, so that the sloshing liquid damper can always perform vibration reduction control on the two orthogonal directions of the wind turbine, namely, the downwind direction and the crosswind direction.

[0041] like Figure 2 As shown, the damper cavity consists of a bottom plate, a top plate, and an outer vertical wall.

[0042] The plane size of the damper cavity 3, the volume of the internal liquid, the material type of the solid particles and the number of layers are all determined by dynamic parameters such as the modal mass, inherent damping ratio and natural frequency of the main structure of the floating wind turbine.

[0043] The liquid level h in the slosh damper can be calculated according to the formula:

[0044]

[0045] The design of the slosh damper is carried out as follows:

[0046] Step 1: Determine the length L of the damper cavity 3 according to the available space at the top of the floating wind turbine tower;

[0047] Step 2: Calculate the first-order frequency ω0 of the floating wind turbine tower (affected by the floating foundation).

[0048] Step 3: Determine (set) the frequency ratio of the slosh damper That is, the ratio of the natural frequency ω1 of the sloshing damper to the first-order frequency ω0 of the floating wind turbine tower, thereby determining the first-order sloshing frequency ω1 of the liquid;

[0049] Step 4: Substitute the gravity acceleration g, the length L of the damper cavity 3 and the value of the natural frequency ω1 of the sloshing damper into formula (1) to determine the liquid depth h;

[0050] Step 5: According to h, the height H of the damper cavity 3 is determined according to the principle of 2h≤H<3h.

[0051] If the obtained design of the sloshing liquid damper is unreasonable, different lengths L of the damper cavity 3 may be selected for iterative optimization until a reasonable design of the sloshing liquid damper is obtained.

[0052] The solid particles 5 are used to enhance the free surface of the liquid 4 , thereby suppressing excessive shaking of the liquid. The solid particles 5 float on the free surface of the liquid 4 , and their density is less than that of the liquid 4 .

[0053] The solid particles 5 are small foam spheres made of light resin material, which have mature manufacturing technology and can be mass-produced. The light resin material can be melamine resin.

[0054] In this embodiment, three layers of solid particles 5 are laid on the upper portion of the free surface of the liquid 4 .

[0055] The solid particles 5 can enhance the free surface of the liquid, prevent or delay the occurrence of wave breaking, and make the sloshing of the liquid in the sloshing damper always maintain a free surface form dominated by the first-order sloshing mode.

[0056] At the same time, the solid particles 5 are dispersed from each other, which further improves the energy consumption level of the sloshing damper.

[0057] Specifically, when a floating wind turbine is subjected to external loads, it vibrates, driving the sloshing damper, causing the liquid in the damper to slosh and the light solid particles on the liquid surface to move. When the liquid sloshes too much, the light solid particles will inhibit the breakage of the liquid surface, allowing the sloshing damper to maintain good vibration reduction performance even when the vibration amplitude of the wind turbine structure is large.

[0058] The damping mesh partition 6 is used to filter (consume) the high-order sloshing mode components of the liquid motion. It is fixed to the inner wall of the damper cavity 3 and is located in the orthogonal direction of the cross.

[0059] A plurality of screen grids are provided on the damping mesh partition 6, and the screen grids allow the liquid 4 to pass through but do not allow the solid particles 5 to pass through.

[0060] Specifically, the position and number of the damping mesh baffles 6 need to take into account the distribution of the velocity field of the liquid 4 inside the damper cavity 3. The specific principles are:

[0061] (1) When the liquid 4 sloshes, there are inevitably multiple modal responses. In addition to the first-order sloshing mode, other (higher-order) sloshing modes will make the free surface of the liquid 4 more susceptible to wave breaking.

[0062] Therefore, it is necessary to suppress it through the damping mesh partition 6, so the damping mesh partition 6 should be set at a position with a larger velocity in the velocity field distribution of the high-order mode (mainly the second-order and third-order modes).

[0063] (2) The damping mesh partition 6 should not be arranged at a position with a relatively large velocity in the first-order modal velocity field distribution, so as to avoid excessively suppressing the first-order modal response and thus reducing the vibration reduction effect of the sloshing liquid damper 3 .

[0064] Among them, the velocity field of the liquid 4 sloshing mode can be calculated using a numerical calculation program to obtain the position with the largest velocity in each mode.

[0065] Working principle of the damping mesh baffle 6: The damping mesh baffle 6 can effectively filter (consume) the high-order sloshing mode components of the liquid motion of the sloshing liquid damper, and realize the liquid motion form dominated by the first-order sloshing mode. Therefore, the placement and number of the damping mesh baffles are determined by the geometric dimensions of the sloshing liquid damper and the liquid depth.

[0066] At the same time, the interaction between the damping mesh baffle 6 and the sloshing liquid can further enhance the energy dissipation of the sloshing liquid damper.

[0067] In addition, the slosh damper is installed above the tower of the floating wind turbine near the nacelle, which can make full use of the space on the top of the tower.

[0068] The basic idea of ​​the present invention can be illustrated by the following experiments.

[0069] For a set of two cups containing the same volume of water and beer, respectively, and applying external excitation to the bottom of the cup, it can be seen that the sloshing amplitude of the beer in the cup is significantly smaller than that of the water in the other cup. And when the external excitation continues to increase and waves break on the free surface of the water, the beer can still slosh while maintaining the continuity of the free surface. The fundamental reason is that when the beer sloshes due to the excitation from the bottom of the cup, foamy hops will be produced on the surface of the liquid due to the sloshing, and the presence of hops plays a role in enhancing the free surface of the beer, thereby avoiding the occurrence of wave breaking in the case of large sloshing.

[0070] The utility model adopts a sloshing liquid damper in a shallow water form.

[0071] The shallow water slosh damper has the characteristics of high inherent damping and large effective slosh mass, and has higher vibration reduction efficiency than the deep water slosh damper.

[0072] When a shallow water sloshing damper is subjected to external excitation (i.e. structural vibration), the liquid in the sloshing damper will undergo sloshing motion including traveling wave and standing wave effects. Its sloshing response includes multiple sloshing modes, generally with the first-order sloshing mode as the main component. The existence of high-order sloshing modes will make the liquid free surface more susceptible to wave breaking. Therefore, enhancing the free surface and filtering out the components of high-order sloshing modes is an effective way to prevent wave breaking on the liquid free surface.

[0073] The floating wind turbine is a rigid-flexible coupling system. The floating foundation has six degrees of freedom of rigid body motion, and the tower will bend elastically in the downwind and acrosswind directions. Under the influence of wind, current, waves, tides and other environmental factors, the floating wind turbine will simultaneously generate tower vibration and rigid body motion of the floating foundation.

[0074] The sloshing damper not only has a good vibration reduction effect on the tower of the floating wind turbine, but also has a certain motion suppression effect on the floating foundation.

[0075] Moreover, when the floating wind turbine undergoes large-scale movement and vibration, the free surface of the liquid can still be kept from being broken and a good vibration reduction effect can be achieved, and it has excellent performance robustness.

[0076] Figure 6 In the figure, Figure (a) shows a sloshing damper with light solid particles laid on the liquid surface, and Figure (b) shows a sloshing damper without light solid particles laid on the liquid surface.

[0077] The two sloshing dampers are subjected to the same external excitation. When wave breaking occurs on the liquid free surface of the sloshing damper in Figure (b), the sloshing damper in Figure (a) can still slosh while maintaining the continuity of the free surface because of the reinforcement of the free surface by lightweight solid particles.

[0078] The above are only preferred embodiments of the present invention and do not limit the present invention in any way. Any technician in the relevant technical field, without departing from the scope of the technical solution of the present invention, may make any equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, which shall be deemed as the content of the technical solution of the present invention and still fall within the protection scope of the present invention.

Claims

1. A free surface enhanced slosh damper for vibration reduction of a floating wind turbine, characterized in that: include: A damper cavity (3), which is a closed cavity filled with liquid (4); Solid particles (5) are used to enhance the surface of the liquid (4) so ​​as to suppress the breakage of the liquid when it is shaken greatly. The solid particles (5) float on the surface of the liquid (4) and have a density less than that of the liquid (4); A damping mesh partition (6) is used to filter high-order sloshing modal components of liquid motion, and is fixed to the inner wall of the damper cavity (3), wherein the damper cavity (3) is a cross-shaped structure; the damping mesh partition (6) is located in an orthogonal direction of the cross; A plurality of screen grids are provided on the damping mesh partition (6), and the screen grids allow liquid (4) to pass through but do not allow solid particles (5) to pass through.

2. The free surface enhanced slosh damper for vibration reduction of a floating wind turbine according to claim 1, characterized in that: Also includes: The output shaft of the rotating motor (7) is fixed to the bottom of the damper cavity (3), and the housing of the rotating motor (7) is fixed to the top of the floating wind turbine tower (2).

3. The free surface enhanced slosh damper for vibration reduction of floating wind turbine according to claim 1, characterized in that: Liquid depth in the damper cavity (3) for: ， ， in, - The first-order frequency of the floating wind turbine tower affected by the floating foundation; -Frequency ratio of the slosh damper; -The first sloshing frequency of the liquid; - Length of the damper cavity (3).

4. The free surface enhanced slosh damper for vibration reduction of a floating wind turbine according to claim 1, characterized in that: The number of layers of the solid particles (5) is N.

5. The free surface enhanced slosh damper for vibration reduction of a floating wind turbine according to claim 1, characterized in that: The solid particles (5) are made of light resin material.

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