A wind turbine blade core structure with combined geometric features

Abstract

The present invention provides a wind turbine blade core structure with combined geometric features. The core structure includes a core body and a plurality of cutting slits and a plurality of obliquely arranged through holes that are discretely distributed on the core body. The plurality of cutting slits and the plurality of obliquely arranged through holes are alternately distributed along the chord direction of the blade. The plane of the plurality of cutting slits is perpendicular to the blade surface and parallel to the span direction of the blade. By reasonably configuring the geometric parameters of the cutting slits and the obliquely arranged through holes, the mechanical properties of the core after resin infusion and the anti-peeling performance between the core and the panel can be targeted and selectively improved. While effectively improving the infusion efficiency of the core, the resin absorption amount of the core is minimized as much as possible, thereby reducing the core weight and cost, and at the same time improving the conformability of the infused core.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite material structure design, and particularly relates to a wind turbine blade core structure with combined geometric features. Background Art

[0002] In recent years, wind energy has received unprecedented attention. Wind power generation is the main form of wind energy utilization, and the proportion of wind power generation in the total power generation has increased rapidly. The blades of wind turbines are the main components for capturing wind energy, and blades with good design and stable quality are important guarantees for the stable power generation and safe operation of wind turbines. As the single-unit power of wind turbines increases, the length of wind power blades also increases accordingly, which puts higher requirements on the strength, stiffness and buckling resistance of the blades, and requires materials and structures with more excellent performance to meet the requirements of blade enlargement.

[0003] In the prior art, the performance of the sandwich structure is improved by optimizing the core processing configuration with a single geometric characteristic. However, in the core processing configuration with a single geometric characteristic, adopting a certain performance-related technology will inevitably neglect the improvement of other performances, and the performance improvement is limited, the mechanical parameters and performance improvement are single, resulting in the inefficient utilization of the internal space of the core.

[0004] Chinese Patent CN201911223864.9 discloses an integrated foam sandwich structure and its reinforcement method. The reinforcement method of this invention only processes cylindrical through-holes with an inclination angle of -90 degrees to 90 degrees on the core material. When the sandwich panel is perfusion-molded, resin columns are formed, which improves the stiffness and strength performance of the sandwich structure. However, the types of performance improvement are single. Although it has a limited improvement in the strength of the panel / core interface, it cannot flexibly adjust the ratio of the resin's contribution to each performance. Chinese Patent CN202121155958.X discloses a PVC foam core material for wind turbine blades. This invention also adopts a single geometric feature processing configuration, that is, V-shaped grooves are opened vertically and horizontally on both the upper and lower sides of the core material. Although the resin infusion efficiency and the conformability of the core material are optimized, the volume ratio of the resin infused into the core material will increase accordingly, which is not conducive to the lightweight of the sandwich structure and cost reduction. Chinese Patent CN202011312660.5 discloses a core material for wind turbine blades and its processing method. This invention adopts a core material processing configuration with V-shaped deep grooves close to the thickness of the core material, which greatly improves the conformability of the core material and the resin infusion efficiency. However, the V-shaped grooves with a large angle will also cause too high a resin mass content, and too small an angle limit will increase the process difficulty and affect the production efficiency. Chinese Patent CN201910164986.9 discloses a structure for cutting, grooving, and punching on the surface of the core material. This solution is to cut one-way deep grooves along the product's curved surface extension direction on the surface of the core material, and one-way shallow grooves along the chord direction of the product's curved surface on the upper and lower surfaces. The self-guiding of the structure is carried out by using the grooves of the new material itself to quickly spread and infiltrate from the perfusion area to the surroundings, and the perfusion of the entire product is completed in a short time. Compared with the traditional method, the use of a large number of guiding auxiliary materials is eliminated. However, the improvement of mechanical properties is limited, and the mechanical parameters and performance improvement are single. Chinese Patent CN201910966203.9 proposes a processing method for a stepped hole type Z-direction reinforced core material. This invention improves the Z-direction compressive performance and shear performance of the core material by proposing a new processing technology to process inclined through-holes with an angle of ±45 degrees to ±60 degrees on the core material. While the mechanical properties of the core material are improved, it also has a positive effect on the strength of the panel / core interface.

[0005] Therefore, it is necessary to provide a core material processing configuration with combined geometric features to meet the requirements of the large-scale of blades. Summary of the Invention

[0006] In order to solve the problem that the existing configurations of core materials cannot meet the requirements of the large-scale of blades. The purpose of this invention is to provide a wind turbine blade core material structure with combined geometric features.

[0007] To achieve the above object, the present invention provides a wind turbine blade core structure with combined geometric features. The core structure includes a core body and a plurality of cutting slits and a plurality of obliquely arranged through holes that are discretely distributed on the core body. The plurality of cutting slits and the plurality of obliquely arranged through holes are alternately distributed along the chord direction of the blade. The planes of the plurality of cutting slits are perpendicular to the blade surface and parallel to the span direction of the blade.

[0008] The wind turbine blade core structure with combined geometric features provided by the present invention has the following characteristics. The plurality of cutting slits include a plurality of full-thickness cutting slits and a plurality of partial-thickness cutting slits. The plurality of obliquely arranged through holes include a plurality of tapered obliquely arranged through holes with tapered ends at both ends and a plurality of cylindrical obliquely arranged through holes. The included angle between the axial direction of the cylindrical obliquely arranged through holes and the upper and lower surfaces of the core body is 30 degrees to 150 degrees.

[0009] The wind turbine blade core structure with combined geometric features provided by the present invention has the following characteristics. The plurality of cutting slits are all perpendicular to the upper and lower surfaces of the core body.

[0010] The wind turbine blade core structure with combined geometric features provided by the present invention has the following characteristics. The full-thickness cutting slits and the partial-thickness cutting slits have the same length, and the full-thickness cutting slits and the partial-thickness cutting slits are alternately distributed at intervals.

[0011] The wind turbine blade core structure with combined geometric features provided by the present invention has the following characteristics. The plurality of obliquely arranged through holes are spaced at the same length interval along the span direction of the blade.

[0012] The wind turbine blade core structure with combined geometric features provided by the present invention has the following characteristics. The axis of the cylindrical obliquely arranged through holes is parallel to the axes of the plurality of cutting slits, and the bottom area of the tapered obliquely arranged through holes is not less than the cross-sectional area of the cylindrical obliquely arranged through holes.

[0013] The wind turbine blade core structure with combined geometric features provided by the present invention has the following characteristics. The tapered obliquely arranged through holes have an arc transition.

[0014] Beneficial effects:

[0015] The wind turbine blade core structure with combined geometric features provided by the present invention is provided with alternately arranged cutting slits and obliquely arranged through holes. By reasonably configuring the parameters of each cutting slit and obliquely arranged through hole, the mechanical properties of the foam core of the sandwich structure and the anti-peeling property of the core and the panel can be selectively improved. While effectively improving the core injection efficiency, the glue absorption of the core should be minimized as much as possible, thereby reducing the core weight and cost. At the same time, the conformability of the injected core can also be improved to a certain extent, thus realizing the efficient utilization of the internal space of the core. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0017] Figure 1 is a schematic structural diagram of the core material structure provided by the present invention;

[0018] Figure 2 is a schematic diagram of the first surface of the core material structure provided by the present invention;

[0019] Figure 3 is a schematic diagram of the second surface of the core material structure provided by the present invention;

[0020] Figure 4 is a top view of the core material structure provided by the present invention;

[0021] Figure 5 is a curve showing the change of the shear modulus of the core material structure provided by the present invention with the inclination angle of the inclined through-hole. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] In order to make the technical means, creative features, achieved purposes and functions of the present invention easy to understand, the following embodiments will specifically describe the turbine blade provided by the present invention in conjunction with the drawings.

[0023] In the description of the embodiments of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0024] In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0025] The terms "installed", "connected", and "joined" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in this invention can be understood according to specific situations.

[0026] As Figures 1-5 shown, a wind turbine blade core structure with combined geometric features is provided. The core structure includes a core body and a plurality of cutting slits 3 and a plurality of obliquely arranged through holes 4 that are discretely distributed on the core body. The plurality of cutting slits 3 and the plurality of obliquely arranged through holes 4 are alternately distributed along the chord direction of the blade. The plane of the plurality of cutting slits 3 is perpendicular to the blade surface 1 and parallel to the span direction 2 of the blade.

[0027] In the above embodiment, there are alternately arranged cutting slits 3 and obliquely arranged through holes 4. By reasonably configuring the parameters of each cutting slit 3 and obliquely arranged through hole 4, the mechanical properties of the foam core material of the sandwich structure and the anti-peeling property between the core material and the panel can be selectively improved. While effectively improving the core material perfusion efficiency, the glue absorption amount of the core material should be minimized as much as possible, thereby reducing the core material weight and cost. At the same time, the conformal property of the perfusion core material can also be improved to a certain extent, so as to realize the efficient utilization of the internal space of the core material.

[0028] In some embodiments, the plurality of cutting slits 3 includes a plurality of full-thickness cutting slits 5 and a plurality of partial-thickness cutting slits 6. The plurality of obliquely arranged through holes 4 includes a plurality of tapered obliquely arranged through holes 8 with tapered ends at both ends and a plurality of cylindrical obliquely arranged through holes 9. The angle 10 between the axial direction of the cylindrical obliquely arranged through hole and the upper and lower surfaces of the core body is 30 degrees to 150 degrees.

[0029] In the above embodiments, cutting slots 3 perpendicular to the upper and lower surfaces are processed on the core material. The cutting slots 3 include a full-thickness cutting part and a partial-thickness cutting part. Among them, the full-thickness cutting slot 5 refers to a cutting slot whose cutting thickness penetrates the entire core material body, and the partial-thickness cutting slot 6 refers to a cutting slot whose cutting thickness is less than the thickness of the core material body. This can greatly improve the tensile and compressive properties of the core material. And because the cutting slot leaves a connecting core material 7 in the partial-thickness cutting part, the volume part of this part of the core material will not be replaced by resin after perfusion. The resin absorption of the core material will be significantly reduced compared to the full-thickness cutting in a single geometric processing configuration. And the resin weight ratio and the contribution degree to various mechanical properties can be flexibly controlled by adjusting the proportion of the full-thickness cutting part and the partial-thickness cutting part of the cutting slot and the cutting depth of the partial-thickness cutting slot. On the other hand, it will also affect the conformability of the core material during the production and processing of the blade. The cutting widths of the full-thickness cutting slot 5 and the partial-thickness cutting slot 6 are the same. During the processing, the partial-thickness cutting slot 6 should be processed first, and then the full-thickness cutting slot 5. The tensile and compressive properties are mainly affected by the geometric factors of the combined cutting slot, mainly the proportion of the full-thickness cutting slot 5. The larger the proportion of this part, the better the mechanical properties of the core material.

[0030] The cylindrical inclined through-hole 8 with an inclination angle of 30 degrees to 150 degrees with respect to the upper and lower surfaces of the core material in its axial direction can maximize the shear resistance of the foam core material without increasing the resin absorption. The setting of the conical inclined through-hole mouth increases the bonding area between the resin and the panel while hardly increasing the resin weight ratio, and maximally improves the interfacial strength between the core material and the panel. In addition, by flexibly changing the geometric dimensions of the conical inclined through-hole 8 and the cylindrical inclined through-hole 9, the resin weight ratio and the contribution degree to various mechanical properties can be flexibly controlled.

[0031] In some embodiments, the plurality of cutting slots 3 are all perpendicular to the upper and lower surfaces of the core material body.

[0032] In some embodiments, the full-thickness cutting slot 5 and the partial-thickness cutting slot 6 have the same length, and the full-thickness cutting slot 5 and the partial-thickness cutting slot 6 are alternately distributed at an interval of 10 mm.

[0033] In some embodiments, the full-thickness cutting slot 5 and the partial-thickness cutting slot 6 have the same length, and the full-thickness cutting slot 5 and the partial-thickness cutting slot 6 are alternately distributed at intervals.

[0034] In some embodiments, the plurality of inclined through-holes are at the same length interval along the blade span direction. The axis of the cylindrical inclined through-hole 9 is parallel to the axes of the plurality of cutting slots 3, and the bottom area of the conical inclined through-hole 8 is not less than the cross-sectional area of the cylindrical inclined through-hole 9. During the processing, the cylindrical inclined through-hole 9 should be processed first, and then the conical inclined through-hole 8.

[0035] In some embodiments, the cylindrical inclined through-hole 9 is inclined at an angle of 60 degrees with respect to the upper surface of the core material body, and the inclination direction is along the blade span direction.

[0036] In the above embodiments, the resin columns formed after pouring through the 60-degree through-holes penetrating the core material greatly improve the shear performance of the core material. The tapered design at both ends of the holes increases the resin fluidity and the contact area between the resin column and the panel, thereby improving the peel resistance strength at the interface between the core material and the panel to a certain extent.

[0037] In some embodiments, the tapered inclined through-hole 8 has an arc transition. This can further reduce the resin infiltration amount while keeping the contact area between the resin and the panel unchanged. In addition, the tapered inclined through-hole opening can also improve the permeability of the sandwich structure, which is beneficial to the high-quality and rapid molding of the blade.

[0038] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention. The above is only the preferred implementation manner of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A wind turbine blade core structure with combined geometric features, characterized in that The core structure includes a core body, and a plurality of cutting slits and a plurality of obliquely arranged through holes that are discretely distributed on the core body. The plurality of cutting slits and the plurality of obliquely arranged through holes are alternately distributed along the chord direction of the blade. The planes of the plurality of cutting slits are perpendicular to the blade surface and parallel to the span direction of the blade. The plurality of cutting slits include a plurality of full-thickness cutting slits and a plurality of partial-thickness cutting slits. The plurality of obliquely arranged through holes include a plurality of conical obliquely arranged through holes with tapered ends and a plurality of cylindrical obliquely arranged through holes. The included angle between the axial direction of the cylindrical obliquely arranged through holes and the upper and lower surfaces of the core body is 30 degrees to 150 degrees.

2. The wind turbine blade core structure with combined geometric features according to claim 1, characterized in that The plurality of cutting slits are all perpendicular to the upper and lower surfaces of the core body.

3. The wind turbine blade core structure with combined geometric features according to claim 1, characterized in that, The full-thickness cutting slits and the partial-thickness cutting slits have the same length, and the full-thickness cutting slits and the partial-thickness cutting slits are alternately distributed at intervals.

4. The wind turbine blade core structure with combined geometric features according to claim 1, characterized in that The plurality of obliquely arranged through holes are spaced at the same length interval in the span direction of the blade.

5. The wind turbine blade core structure with combined geometric features according to claim 1, characterized in that, The axes of the cylindrical obliquely arranged through holes are parallel to the axes of the plurality of cutting slits, and the bottom area of the conical obliquely arranged through holes is not less than the cross-sectional area of the cylindrical obliquely arranged through holes.

6. The wind turbine blade core structure with combined geometric features according to claim 1, characterized in that, The conical obliquely arranged through holes have an arc transition.

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