Novel scour protection structure for wind power foundations

Abstract

The application discloses a novel scouring prevention structure of a wind power foundation, which comprises a wing-shaped flow guide structure, a guard ring structure and a pile foundation main body, the wing-shaped flow guide structure and the guard ring structure are sleeved on the pile foundation main body, the wing-shaped flow guide structure is located on the guard ring structure, the guard ring structure is close to a seabed, a rotary cavity is arranged in the wing-shaped flow guide structure, the rotary cavity extends from the front end of the wing-shaped flow guide structure to the rear end thereof, a water inlet is arranged at the front end of the rotary cavity, a filter screen is arranged on the water inlet, and a water outlet is arranged at the tail end of the rotary cavity. The application can effectively reduce a horseshoe-shaped vortex and a wake vortex, and reduce the local scouring intensity.

Description

Technical Field

[0001] This invention relates to offshore horizontal axis wind turbine foundations, particularly offshore monopile wind turbine foundations and floating wind turbine pile anchor foundations, specifically a novel scour-resistant structure for wind turbine foundations. Background Technology

[0002] Wind power, as a high-quality renewable resource, has seen vigorous development. Currently, wind power equipment is trending towards both onshore and offshore applications. Compared to onshore wind power, offshore wind power has better wind resources; however, offshore wind turbines also face harsher environments. After a wind farm is built, the turbine foundation is subjected to hydrodynamic loads such as waves and currents, resulting in significant localized scouring. This causes water flow to be impeded by the foundation, forming eddies near the foundation, which dig and wash away sediment, creating scour pits and increasing the volume of the exposed foundation, posing serious safety hazards. The flow around a monopile foundation can be broadly categorized into four types, such as... Figure 12 As shown, the scouring is divided into front pile backwater, horseshoe vortex, downward jet, and wake vortex. Among them, the horseshoe vortex causes front pile scouring, while the wake vortex mainly causes rear pile scouring. Therefore, we seek an effective device to reduce horseshoe vortex and wake vortex to reduce the intensity of local scouring. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a novel wind power foundation anti-scour structure that can effectively reduce horseshoe vortices and wake eddies and reduce local scour intensity.

[0004] This invention is achieved through the following technical solution: a novel wind power foundation anti-scour structure, comprising an airfoil guide structure, a protective ring structure, and a pile foundation body. The airfoil guide structure and the protective ring structure are sleeved on the pile foundation body, with the airfoil guide structure located on the protective ring structure. The protective ring structure is close to the seabed. A rotating cavity is provided inside the airfoil guide structure, extending from the front end to the rear end of the airfoil guide structure. A water inlet is provided at the front end of the rotating cavity, and a filter screen is provided on the water inlet. A water outlet is provided at the rear end of the rotating cavity.

[0005] Furthermore: the airfoil guide structure includes an upper cover plate, a lower cover plate, an airfoil shell, and a partition plate. The upper cover plate is disposed on the top of the airfoil shell, and the lower cover plate is disposed on the bottom of the airfoil shell. The interior of the airfoil shell is a hollow structure, and the hollow structure is divided into two mutually symmetrical and independent rotating cavities by the partition plate.

[0006] Furthermore: the protective ring structure includes a bottom and a top, the bottom is circular, the top is wing-shaped, the shape of the top is the same as the shape of the lower cover plate, a curved slope is formed between the edge of the bottom and the edge of the top, the lower cover plate is connected to the top, and the bottom is close to the seabed.

[0007] Furthermore: the upper cover plate has a positioning hole, the airfoil shell has an installation hole, the lower cover plate has a through hole, the top has a limit hole, and the bottom has a connecting hole communicating with the limit hole. The positioning hole, installation hole, through hole, limit hole, and connecting hole are vertically aligned on the same straight line. The pile foundation body passes through the positioning hole, installation hole, through hole, limit hole, and connecting hole sequentially from top to bottom. Bearings are provided between the outer periphery of the pile foundation body and the positioning hole, and between the outer periphery of the pile foundation body and the connecting hole.

[0008] Furthermore, the mounting hole is located between the two rotating cavities.

[0009] Furthermore, the curved slope extends from the top edge to the bottom edge.

[0010] Furthermore: each of the rotary cavities includes a front cavity section, a middle cavity section, and a rear cavity section. The middle cavity section is semi-circular in shape. The mounting hole is located between the two middle cavities. The two ends of the middle cavity section are respectively connected to the tail end of the front cavity section and the front end of the rear cavity section. The water inlet is located at the front end of the front cavity section, and the water outlet is located at the tail end of the rear cavity section.

[0011] Furthermore, each cavity has a plurality of water outlet holes at its rear end, and the plurality of water outlet holes are arranged in two rows.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1. By fitting an airfoil-shaped flow guide structure and a retaining ring structure onto the main body of the pile foundation, with the airfoil-shaped flow guide structure located on top of the retaining ring structure, which is close to the seabed, and a rotating cavity inside the airfoil-shaped flow guide structure extending from its front end to its rear end, a water inlet with a filter screen is located at the front end of the rotating cavity, and a water outlet is located at the rear end of the rotating cavity, the airfoil-shaped flow guide structure, suitable for high Reynolds number conditions, is used as the external shape, providing excellent hydrodynamic performance. This allows the water flow to extend from the flow separation point of the main body of the pile foundation to the rear end of the airfoil-shaped flow guide structure, thereby suppressing the formation of Karman vortex streets and avoiding the generation of wake vortices around the main body of the pile foundation, effectively reducing the impact on the pile foundation. The main body's flow direction reduces the scouring volume behind it, achieving the purpose of scouring. When the flow comes from directly in front, it enters the rotating cavity through the filter screen from the inlet and is discharged from the outlet at the tail end of the rotating cavity. Through the filter screen, some of the energy of the incoming flow can be absorbed. Through the rotating cavity, the flow velocity of the incoming flow can be further reduced. Thus, the rotating cavity further reduces the flow rate of the fluid on both sides of the airfoil guide structure and the intensity of the downward jet. The rotating cavity can also reduce the flow velocity of the water flowing through the middle of the airfoil guide structure, thereby reducing scouring. Since the fluid in the middle of the airfoil guide structure can flow along the rotating cavity through the entire airfoil guide structure, it can generate a horseshoe-shaped vortex with a smaller intensity and weaken the intensity of the downward jet.

[0014] 2. By setting the top of the retaining ring structure as an airfoil and the bottom of the retaining ring structure as a circle, the top and the airfoil flow guide structure are connected, and the bottom is close to the seabed. A curved slope is formed between the bottom edge and the top edge, and the curved slope extends from the top edge to the bottom edge. When the water flows, the water flow is divided into upper and lower parts by the slope of the curved slope. The upper fluid forms an upward jet along the slope of the curved slope, which cancels out the downward jet of local scouring. At the same time, the lower fluid flows along the gap between the seabed and the retaining ring structure, and the bottom of the retaining ring structure is close to the seabed. The space reserved for the formation of horseshoe vortices is small, which can effectively reduce the intensity of horseshoe vortices, thereby reducing the amount of scouring in front of the main pile foundation.

[0015] 3. By providing positioning holes in the upper cover plate, mounting holes in the airfoil shell, through holes in the lower cover plate, limiting holes at the top, and connecting holes at the bottom communicating with the limiting holes, the pile foundation body passes through the positioning holes, mounting holes, through holes, limiting holes, and connecting holes sequentially from top to bottom. Bearings are provided between the outer periphery of the pile foundation body and the positioning holes, and between the outer periphery of the pile foundation body and the connecting holes. This allows the anti-scour structure of the present invention to be aligned with the incoming flow direction. Similar to a single-point moored wind turbine, this anti-scour structure generates a torque difference based on the different incoming flow directions, thereby spontaneously aligning with the incoming flow direction. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the present invention. Figure 1 ;

[0017] Figure 2 This is a schematic diagram of the structure of the present invention. Figure 2 ;

[0018] Figure 3 This is a structural exploded view of the present invention;

[0019] Figure 4 This is a schematic diagram of the connection between the airfoil guide structure and the protective ring structure of the present invention;

[0020] Figure 5 This is a schematic diagram of the airfoil guide structure of the present invention. Figure 1 ;

[0021] Figure 6 This is a schematic diagram of the airfoil guide structure of the present invention. Figure 2 ;

[0022] Figure 7 This is a schematic diagram of the internal structure of the airfoil guide structure of the present invention;

[0023] Figure 8 for Figure 7 Top view;

[0024] Figure 9 This is a schematic diagram of the protective ring structure of the present invention;

[0025] Figure 10 This is a side view of the retaining ring structure of the present invention;

[0026] Figure 11 This is a bottom view of the protective ring structure of the present invention;

[0027] Figure 12 A schematic diagram of the local disturbance flow field and scour pattern near the main body of the pile foundation;

[0028] Figure 13 This is a force diagram of the present invention when the direction of the incoming flow changes;

[0029] Figure 14 The horizontal flow field diagram is shown without the influence of the airfoil guide structure of the present invention.

[0030] Figure 15 This is a flow field diagram of the horizontal plane under the influence of the airfoil guide structure of the present invention;

[0031] Figure 16 The longitudinal cross-sectional flow field diagram is shown without the influence of the airfoil guide structure of the present invention.

[0032] Figure 17 This is a longitudinal section flow field diagram under the influence of the airfoil guide structure of the present invention;

[0033] Figure 18This is a longitudinal cross-sectional flow field diagram under the influence of the protective ring structure of the present invention.

[0034] Explanation of reference numerals in the attached drawings: 1-Airfoil guide structure, 2-Guard ring structure, 3-Pile foundation body, 4-Rotating cavity, 5-Inlet, 6-Filter screen, 7-Outlet hole, 8-Upper cover plate, 9-Lower cover plate, 10-Airfoil shell, 11-Baffle plate, 12-Bottom, 13-Top, 14-Curved slope, 15-Positioning hole, 16-Mounting hole, 17-Through hole, 18-Limiting hole, 19-Connecting hole, 20-Bearing, 21-Front section of cavity, 22-Middle section of cavity, 23-Rear section of cavity, A-Water backfill in front of pile, B-Horseshoe vortex, C-Downward jet, D-Wake vortex, E-Scrubber pit. Detailed Implementation

[0035] Appendix Figure 1 To be continued Figure 11 The schematic diagram of an embodiment of a novel wind power foundation anti-scour structure provided by the present invention includes an airfoil guide structure 1, a protective ring structure 2, and a pile foundation body 3. The airfoil guide structure 1 and the protective ring structure 2 are sleeved on the pile foundation body 3, and the airfoil guide structure 1 is located on the protective ring structure 2. The protective ring structure 2 is close to the seabed. A rotating cavity 4 is provided inside the airfoil guide structure 1. The rotating cavity 4 extends from the front end of the airfoil guide structure 1 to its rear end. A water inlet 5 is provided at the front end of the rotating cavity 4, and a filter screen 6 is provided on the water inlet 5. A water outlet 7 is provided at the rear end of the rotating cavity 4.

[0036] The airfoil guide structure 1 includes an upper cover plate 8, a lower cover plate 9, an airfoil shell 10, and a partition plate 11. The upper cover plate 8 is located at the top 13 of the airfoil shell 10, and the lower cover plate 9 is located at the bottom 12 of the airfoil shell 10. The airfoil shell 10 has a hollow structure inside, and the hollow structure is divided into two mutually symmetrical and independent rotating cavities 4 by the partition plate 11.

[0037] The protective ring structure 2 includes a bottom 12 and a top 13. The bottom 12 has a circular structure and the top 13 has a wing-shaped structure. The shape of the top 13 is the same as that of the lower cover plate 9. A curved slope 14 is formed between the edges of the bottom 12 and the edges of the top 13. The lower cover plate 9 and the top 13 are connected, and the bottom 12 is close to the seabed.

[0038] The upper cover plate 8 has a positioning hole 15, the airfoil shell 10 has an installation hole 16, the lower cover plate 9 has a through hole 17, the top 13 has a limiting hole 18, and the bottom 12 has a connecting hole 19 that communicates with the limiting hole 18. The positioning hole 15, the installation hole 16, the through hole 17, the limiting hole 18, and the connecting hole 19 are located on the same straight line vertically. The pile foundation body 3 passes through the positioning hole 15, the installation hole 16, the through hole 17, the limiting hole 18, and the connecting hole 19 from top to bottom. Bearings 20 are provided between the outer periphery of the pile foundation body 3 and the positioning hole 15, and between the outer periphery of the pile foundation body 3 and the connecting hole 19.

[0039] Because the actual direction of ocean currents can change, to adapt to currents in various directions, the anti-scour structure of this invention incorporates bearings 20 between the outer periphery of the pile body 3 and the positioning hole 15, and between the outer periphery of the pile body 3 and the connecting hole 19, allowing the anti-scour structure to align with the incoming current direction. Similar to a single-point moored wind turbine, this anti-scour structure generates a torque difference based on the direction of the incoming current, thus spontaneously aligning itself with the incoming current direction. The forces acting on this anti-scour structure when the current direction changes are as follows: Figure 13 As shown. Since the anti-scour structure is connected to the main pile foundation 3 at a relatively forward position, after the flow direction changes, due to the large force-bearing area at the rear end and the long lever arm, a large torque will be generated, causing the tail end of the airfoil guide structure 1 to point in the opposite direction to the incoming flow, while the front end of the airfoil guide structure 1 points in the same direction as the incoming flow, thereby achieving the effect of automatically meeting the flow.

[0040] Mounting hole 16 is located between the two rotating cavities 4.

[0041] The curved slope 14 extends from the edge of the top 13 to the edge of the bottom 12.

[0042] Each rotating cavity 4 includes a front cavity section 21, a middle cavity section 22, and a rear cavity section 23. The middle cavity section 22 is semi-circular. The mounting hole 16 is located between the two middle cavity sections 22. The two ends of the middle cavity section 22 are respectively connected to the tail end of the front cavity section 21 and the front end of the rear cavity section 23. The water inlet 5 is located at the front end of the front cavity section 21, and the water outlet 7 is located at the tail end of the rear cavity section 23.

[0043] Each cavity rear section 23 is provided with multiple water outlet holes 7 at its tail end, and the multiple water outlet holes 7 are arranged in two rows.

[0044] Since the diameter of most of the piles in the main body of offshore wind turbines is over 10m, according to Reynolds' calculation formula:

[0045] Re = ρvd / μ

[0046] Where ρ is the fluid density, and the density of seawater is taken as 1.035 × 10⁻⁶. 3 kg / m 3 v is the flow velocity in m / s; d is the characteristic length in meters (m), which is the diameter for a cylinder; μ is the dynamic viscosity coefficient, taken as 1.0565 × 10⁻⁶ for seawater at 20°C. -3 Pa·s.

[0047] Substituting the relevant parameters, its Reynolds number is 10 7The magnitude is high, belonging to the high Reynolds number state. Therefore, the pressure surface of the airfoil 10 is enlarged based on the airfoil NACA0012, which is suitable for high Reynolds numbers, as its shape. Through computational fluid dynamics simulation, the flow separation point of water flowing through the pile foundation body 3 is obtained. The chord length is increased so that the flow separation point of water flowing through the pile foundation body 3 is delayed to the tail end of the airfoil 10, thereby suppressing the formation of the Karman vortex street (e.g., Figure 15 As shown in the figure, this design avoids the formation of wake vortices around the main pile foundation 3, effectively reducing the scouring behind the main pile foundation 3 in the direction of incoming flow, thus achieving the purpose of scouring prevention. To more intuitively demonstrate the principle and function of the airfoil guide structure 1 of this invention, a comparison is made between the horizontal flow field diagrams without and with the airfoil guide structure 1. See [reference needed]. Figure 14 and Figure 15 , Figure 14 The horizontal flow field diagram is shown for the existing pile foundation body 3 without the airfoil guide structure 1. Figure 14 The symbol F indicates the wake vortex, which extends backward to form a von Kármán vortex street. Figure 15 A horizontal flow field diagram was generated after the airfoil-shaped flow guide structure 1 was installed on the main body 3 of the pile foundation. Figure 14 and Figure 15 The comparison shows that, under the influence of the airfoil-shaped flow guide structure 1, the pile foundation body 3 can avoid the generation of a wake vortex around the cylindrical flow around the pile foundation body 3.

[0048] The front end of the airfoil 10 faces the direction of incoming flow, that is, the front end of the front section 21 of the rotating cavity 4 faces the direction of incoming flow. The inlet 5 is located at the front end of the front section 21, and a filter screen 6 is installed on the inlet 5. The tail end of the front section 21 is connected to the middle section 22, and the tail end of the middle section 22 is connected to the rear section 23. The outlet 7 is located at the tail end of the rear section 23. When the airfoil 10 flows directly in front of the front end, the flow enters the front section 21 and the middle section 23 of the cavity sequentially through the inlet 5 and the filter screen 6. 22. The water flows through the rear section 23 of the cavity and then exits through the outlet 7. When the incoming flow passes through the filter screen 6, it can first absorb some energy through the filter screen 6. Then, it can further reduce the flow velocity of the incoming flow by passing through the front section 21, the middle section 22, and the rear section 23 of the cavity. Finally, it exits through the outlet 7, thereby achieving the purpose of reducing the flow rate of the fluid passing through the two outer sides of the airfoil 10 and the intensity of the downward jet through the rotating cavity 4, and reducing the flow velocity of the water flow through the middle of the airfoil 10, thereby reducing the scouring effect. Moreover, since the fluid in the middle of the airfoil 10 can flow along the rotating cavity 4 through the entire airfoil 10, it can generate a horseshoe-shaped vortex with a smaller intensity and weaken the intensity of the downward jet, thus playing a better protective role. In order to more intuitively show the principle and function of the airfoil guide structure 1 of the present invention, the longitudinal section flow field diagram without the airfoil guide structure 1 and the longitudinal section flow field diagram with the airfoil guide structure 1 are compared. See Figure 16 and Figure 17 , Figure 16 The longitudinal section flow field diagram is shown for the existing pile foundation body 3 without the airfoil guide structure 1. Figure 16 The location indicated by the symbol G forms a horseshoe-shaped vortex. Figure 17 The longitudinal section flow field diagram is shown after the airfoil guide structure 1 is installed on the main body 3 of the pile foundation. Figure 17 The location indicated by the symbol H forms a horseshoe-shaped vortex, through Figure 16 and Figure 17 Comparison shows that the rotating cavity 4 inside the airfoil shell 10 of the airfoil guide structure 1 increases the flux of the central fluid. Figure 17 The intensity of the horseshoe vortex indicated by the standard designation H is less than Figure 16 The strength of the horseshoe-shaped vortex indicated by the reference numeral G means that, under the influence of the airfoil-shaped guide structure 1, the main body of the pile foundation 3 can generate a horseshoe-shaped vortex with a smaller intensity and weaken the downward jet intensity.

[0049] By setting a protective ring structure 2 at the bottom 12 of the airfoil-shaped flow guide structure 1, with the bottom 12 of the protective ring structure 2 close to the seabed, and by setting the top 13 of the protective ring structure 2 as an airfoil and the bottom 12 of the protective ring structure 2 as a circle, a curved slope 14 is formed between the edge of the bottom 12 and the edge of the top 13, and the curved slope 14 extends from the edge of the top 13 to the edge of the bottom 12. That is, the curved slope 14 is below the front end of the airfoil shell 10. When the flow comes in, the water flow is divided into upper and lower parts by the slope of the curved slope 14. The upper fluid forms an upward jet along the slope of the curved slope 14, which cancels out the downward jet of local scouring. At the same time, the lower fluid flows along the seabed and the gap between the protective ring structure 2. Since the bottom 12 of the protective ring structure 2 is close to the seabed, the space reserved for the formation of horseshoe vortices is small, which can effectively suppress the intensity of the horseshoe vortices generated, thereby reducing the amount of scouring in front of the main body of the pile foundation 3. Figure 18 As shown, Figure 18 The reference numeral I indicates the downward jet, the reference numeral J indicates the upward jet, and the reference numeral K indicates the gap between the seabed and the protective ring structure 2. The upward and downward jets cancel each other out at the connection.

[0050] The above detailed description is a specific description of feasible embodiments of the present invention. These embodiments are not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included in the patent scope of this case.

Claims

1. An erosion protection structure for a wind power foundation, characterized in that: The application relates to a pile foundation structure, which comprises an airfoil guide structure, a retainer structure and a pile foundation body, the airfoil guide structure and the retainer structure are sleeved on the pile foundation body, the airfoil guide structure is located on the retainer structure, the retainer structure is close to a seabed, the airfoil guide structure is internally provided with a rotary cavity, the rotary cavity extends from the front end of the airfoil guide structure to the rear end of the airfoil guide structure, the front end of the rotary cavity is provided with a water inlet, the water inlet is provided with a filter screen, and the tail end of the rotary cavity is provided with a water outlet hole. The airfoil guide structure comprises an upper cover plate, a lower cover plate, an airfoil shell and a partition plate, the airfoil shell is internally provided with a hollow structure, and the hollow structure is divided into two mutually symmetrical and independent rotary cavities by the partition plate. Each rotary cavity comprises a cavity front section, a cavity middle section and a cavity rear section, the cavity middle section is in a semicircular arc shape, the airfoil shell is internally provided with a mounting hole, the mounting hole is located between the two cavity middle sections, the two ends of the cavity middle section are respectively connected to the tail end of the cavity front section and the front end of the cavity rear section, the water inlet is arranged at the front end of the cavity front section, and the water outlet hole is arranged at the tail end of the cavity rear section. The tail end of each cavity rear section is provided with a plurality of water outlet holes, and the plurality of water outlet holes are arranged in two rows. The retainer structure comprises a bottom and a top, the bottom is in a circular structure, the top is in an airfoil structure, the shape of the top is the same as that of the lower cover plate, a curved slope is formed between the edge of the bottom and the edge of the top, the lower cover plate is connected with the top, and the bottom is close to the seabed.

2. The scour protection structure of claim 1, wherein: The upper cover plate is arranged at the top of the airfoil shell, and the lower cover plate is arranged at the bottom of the airfoil shell.

3. The scour protection structure of claim 2, wherein: The upper cover plate is provided with a positioning hole, the lower cover plate is provided with a through hole, the top is provided with a limiting hole, the bottom is provided with a connecting hole which is in communication with the limiting hole, the positioning hole, the mounting hole, the through hole, the limiting hole and the connecting hole are located on the same straight line in the vertical direction, the pile foundation body sequentially passes through the positioning hole, the mounting hole, the through hole, the limiting hole and the connecting hole from top to bottom, and bearings are arranged between the outer periphery of the pile foundation body and the positioning hole and between the outer periphery of the pile foundation body and the connecting hole.

4. The scour protection structure of claim 3, wherein: The mounting hole is located between the two rotary cavities.

5. The scour protection structure of claim 4, wherein: The curved slope extends from the edge of the top to the edge of the bottom.

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