A Fluid-Structure Coupling Analysis Method for Wind Turbine Blades

Abstract

The present invention discloses a fluid-structure coupling analysis method for wind turbine blades, comprising: step S1: establishing an original three-dimensional model C0 of the blade based on the original blade shape parameters and the original airfoil three-dimensional coordinate points; step S2: calculating the wind turbine flow field using CFD simulation software based on the original three-dimensional model C0 of the blade, and obtaining the blade structural deformation using CAE structural analysis software; and step S3: establishing a relationship between load mapping and blade deformation, performing an iterative solution, and obtaining the blade load and deformation. The present invention has the advantages of simple principle, easy operation, and high accuracy.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of wind power generation, and in particular to a fluid-solid coupling analysis method for wind turbine blades. Background Art

[0002] With the advancement of wind turbine technology, blade power levels are increasing, blade lengths are growing, and consequently, blade weight is increasing. Lightweight blade design inevitably results in reduced blade stiffness and increased flexibility. However, during operation, wind turbine blades experience coupling between fluid and solid matter, making them susceptible to deformation. This not only affects blade power generation performance but also poses a safety risk to the main engine.

[0003] In order to calculate the stress state and deformation of wind turbine blades more accurately, it is necessary to perform fluid-solid coupling analysis of the blades.

[0004] There is relatively little research on the fluid-structure interaction system of wind turbine blades in the existing technology. The main reasons are as follows:

[0005] 1. Wind turbine blades deform greatly during operation. Traditional fluid-structure coupling analysis methods are not suitable for analyzing large-sized and highly deformed wind turbine blades.

[0006] 2. The structural properties of the blade are complex and involve composite material layup design, making it difficult to establish an accurate structural analysis model;

[0007] 3. The deformation of wind turbine blades is large, which makes it difficult to reconstruct the flow field grid;

[0008] 4. After the blade is deformed, the difference between the spatial positions of the flow field grid and the structural grid makes data transmission between the two difficult. Summary of the Invention

[0009] The technical problem to be solved by the present invention is: in response to the technical problems existing in the prior art, the present invention provides a fluid-solid coupling analysis method for wind turbine blades which has a simple principle, is easy to operate and has high precision.

[0010] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0011] A fluid-structure coupling analysis method for a wind turbine blade, comprising:

[0012] Step S1: establishing an original three-dimensional model C0 of the blade according to the original shape parameters of the blade and the original airfoil three-dimensional coordinate points;

[0013] Step S2: Based on the original three-dimensional model C0 of the blade, the fan flow field is calculated using CFD simulation software, and the blade structural deformation is obtained using CAE structural analysis software;

[0014] Step S3: Establish a connection between the load mapping and the blade deformation, perform iterative solution, and obtain the load and deformation of the blade.

[0015] As a further improvement to the analysis method of the present invention: in step S2, CFD simulation software is used to calculate the fan flow field, and a CFD flow field simulation analysis model is created based on the original three-dimensional model C0 of the blade and the flow field boundary conditions to calculate the blade surface load pressure load P0.

[0016] As a further improvement to the analysis method of the present invention: in step S2, CAE structural analysis software is used to calculate the blade structural deformation, and a CAE structural simulation analysis model F0 is created based on the original three-dimensional model C0 of the blade and the structural layup information; the blade surface load pressure load P0 is loaded as a load into the CAE model F0, and the blade tip deformation DT0 is calculated.

[0017] As a further improvement to the analysis method of the present invention: in step S3, based on the judgment basis of the relative deformation of the blade tip, it is determined whether the flow field and structural simulation calculations have converged; if the calculations have converged, the load and shape are output; if not, the deformed shape is output, and the CFD flow field model and CAE structural model are reconstructed, and the load mapping is re-performed until the relative deformation of the blade tip reaches the convergence standard, the calculation is determined to be converged, and the final blade load and blade deformation are output.

[0018] As a further improvement to the analysis method of the present invention: in step S3, it is determined whether the relative deformation ΔDT of the blade tip satisfies or is less than or equal to a set threshold. If so, the shape C1 is output; if not, an iterative solution is performed.

[0019] As a further improvement to the analysis method of the present invention: the threshold value is set at 2%-7%.

[0020] As a further improvement to the analysis method of the present invention: the threshold value is set to 5%.

[0021] As a further improvement to the analysis method of the present invention, the iterative solution process includes:

[0022] Step S100: Based on the blade three-dimensional model C N and flow field boundary conditions, create a CFD simulation analysis model, and calculate the blade surface pressure load P N ; The blade three-dimensional model C N is the three-dimensional model of the blade constructed at the Nth time, and the blade surface pressure load P N is the blade load obtained at the Nth time; where N is the number of cycles and N is a natural number;

[0023] Step S200: Based on the blade three-dimensional model CN As well as structural ply information, create CAE structural simulation analysis model F N , the structural simulation analysis model F N The structural simulation analysis model constructed for the Nth time; the blade surface pressure load P N As a load applied to the CAE model F N Calculate the blade tip deformation DT N ; The blade tip deformation DT N is the deformation of the blade tip at the Nth time;

[0024] Step S300: Determine whether the relative deformation ΔDT of the blade tip satisfies a threshold value less than or equal to the set threshold value. If so, output the shape C. N+1 If not, the calculation does not converge, and the iteration continues to return to step S100; if not, the calculation converges and the final load and tip deflection of the blade are output.

[0025] As a further improvement to the analysis method of the present invention: the original shape parameters of the blade include chord length, twist angle, pre-bend, relative thickness, and pitch axis position.

[0026] Compared with the prior art, the advantages of the present invention are:

[0027] The present invention's fluid-structure interaction analysis method for wind turbine blades features a simple principle, ease of operation, and high precision. It accurately simulates the loads acting on the blade surface during operation, maps these loads to the structure, and calculates structural deformation. Through multiple iterations, a stable state is achieved, resulting in blade torque and deformation.

[0028] 2. The present invention's fluid-structure coupling analysis method for wind turbine blades facilitates the loading of loads from CFD simulation analysis onto the blade CAE model. The present invention uses CAE to calculate blade deformation and outputs this deformation as a precise three-dimensional geometric shape. Furthermore, the present invention uses this new shape for structural layering and CFD flow field simulation analysis, resulting in a precise model. Furthermore, the present invention uses blade tip deflection as the basis for computational convergence, providing a clear criterion. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic flow diagram of the method of the present invention.

[0030] Figure 2 It is a schematic diagram of the principle of the present invention in a specific application example.

[0031] Figure 3 Schematic diagram of creating a three-dimensional blade shape C0 by CAD in a specific application example of the present invention;

[0032] Figure 4It is a schematic diagram of a CFD fluid simulation model created by CFD simulation software in a specific application example of the present invention.

[0033] Figure 5 It is a schematic diagram of surface pressure obtained through CFD simulation in a specific application example of the present invention.

[0034] Figure 6 It is a schematic diagram of creating a structural analysis model through CAE in a specific application example of the present invention.

[0035] Figure 7 It is a schematic diagram of structural deformation obtained by mapping the surface pressure obtained by CFD onto the structural analysis model in a specific application example of the present invention. DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] like Figure 1 As shown, the fluid-structure coupling analysis method for wind turbine blades of the present invention includes:

[0038] Step S1: establishing an original three-dimensional model C0 of the blade according to the original shape parameters of the blade and the original airfoil three-dimensional coordinate points;

[0039] Step S2: Based on the original three-dimensional model C0 of the blade, the fan flow field is calculated using CFD simulation software, and the blade structural deformation is obtained using CAE structural analysis software;

[0040] Step S3: Establish a connection between the load mapping and the blade deformation, perform iterative solution, and obtain the load and deformation of the blade.

[0041] In a specific application example, in step S2, the fan flow field is calculated using CFD simulation software. A CFD flow field simulation analysis model is created based on the original three-dimensional model C0 of the blade and the flow field boundary conditions to calculate the blade surface load pressure load P0.

[0042] In a specific application example, in step S2, CAE structural analysis software is used to calculate the blade structural deformation. A CAE structural simulation analysis model F0 is created based on the original three-dimensional model C0 of the blade and the structural layup information. The blade surface load pressure load P0 is loaded as a load into the CAE model F0 to calculate the blade tip deformation DT0.

[0043] In a specific application example, in step S3, the present invention determines whether the flow field and structural simulation calculations have converged based on the judgment basis of the relative deformation of the blade tip; if the calculation converges, the load and shape are output; if not, the deformed shape is output, and the CFD flow field model and CAE structural model are reconstructed, and the load mapping is re-performed until the relative deformation of the blade tip reaches the convergence standard, the calculation is determined to be converged, and the final blade load and blade deformation are output.

[0044] In a specific application example, in step S3, it is determined whether the relative deformation ΔDT of the blade tip satisfies or is less than or equal to a set threshold. If so, the shape C1 is output; if not, an iterative solution is performed.

[0045] In a specific application example, the set threshold is 2%-7%, preferably 5%.

[0046] In a specific application example, the iterative solution process includes:

[0047] Step S100: Based on the blade three-dimensional model C N and flow field boundary conditions, create a CFD simulation analysis model, and calculate the blade surface pressure load P N ; The blade three-dimensional model C N is the three-dimensional model of the blade constructed at the Nth time, and the blade surface pressure load P N is the blade load obtained at the Nth time; where N is the number of cycles and N is a natural number;

[0048] Step S200: Based on the blade three-dimensional model C N As well as structural ply information, create CAE structural simulation analysis model F N , the structural simulation analysis model F N The structural simulation analysis model constructed for the Nth time; the blade surface pressure load P N As a load applied to the CAE model F N Calculate the blade tip deformation DT N ; The blade tip deformation DT N is the deformation of the blade tip at the Nth time;

[0049] Step S300: Determine whether the relative deformation ΔDT of the blade tip satisfies a threshold value less than or equal to the set threshold value. If so, output the shape C. N+1 If not, the calculation does not converge, and the iteration continues to return to step S100; if not, the calculation converges and the final load and tip deflection of the blade are output.

[0050] In a specific application example, the original shape parameters of the blade include chord length, twist angle, pre-bend, relative thickness, and pitch axis position.

[0051] The CFD simulation software in the present invention refers to spatially discretizing the simulated model and then using numerical solution methods to solve the differential equations that control fluid flow, thereby obtaining the discrete distribution of the flow field of the fluid flow in a continuous area, thereby approximately simulating the fluid flow situation.

[0052] The CAE structural analysis software in the present invention refers to discretizing the structural model using a grid, using a finite number of easily analyzable units to represent a complex object, connecting the units with each other through a finite number of nodes, and then comprehensively solving the problem based on deformation coordination.

[0053] From the above, it can be seen that the fluid-solid coupling analysis method of wind turbine blades of the present invention decomposes the fluid-solid coupling problem of wind turbine blades into flow field analysis and structural analysis for independent solution. CFD simulation software is used to calculate the wind turbine flow field, and CAE structural analysis software is used to calculate the blade structural deformation. The two are connected through load mapping and blade deformation, and an iterative solution is performed to finally obtain the load and deformation of the blade.

[0054] The present invention takes a certain 5MW wind turbine as an example, and creates the blade three-dimensional shape C0 by CAD, see Figure 3 As shown; Create a CFD fluid simulation model through CFD simulation software, see Figure 4 As shown; the surface pressure is obtained by CFD simulation, see Figure 5 As shown; create a structural analysis model through CAE, see Figure 6 As shown; the surface pressure obtained by CFD is mapped to the structural analysis model to obtain the structural deformation, see Figure 7 Output the deformed shape. Repeat steps 1-5 until the relative deformation of the blade tip is ≤5%, which is considered convergence and the final result is obtained.

[0055] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions based on the principles of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A fluid-structure coupling analysis method for wind turbine blades, characterized in that: include: Step S1: establishing an original three-dimensional model C0 of the blade according to the original shape parameters of the blade and the original airfoil three-dimensional coordinate points; Step S2: Based on the original three-dimensional model C0 of the blade, the fan flow field is calculated using CFD simulation software, and the blade structural deformation is obtained using CAE structural analysis software; Step S3: Establish a connection between the load mapping and the blade deformation, perform iterative solution, and obtain the load and deformation of the blade; In step S3, based on the judgment basis of the relative deformation of the blade tip, it is determined whether the flow field and structural simulation calculations have converged; if the calculations have converged, the load and shape are output; if not, the deformed shape is output, and the CFD flow field model and CAE structural model are reconstructed, and the load mapping is re-performed until the relative deformation of the blade tip reaches the convergence standard, the calculation is determined to be converged, and the final blade load and blade deformation are output; The iterative solution process includes: Step S100: Based on the blade three-dimensional model C N and flow field boundary conditions, create a CFD simulation analysis model, and calculate the blade surface pressure load P N ; The blade three-dimensional model C N is the three-dimensional model of the blade constructed at the Nth time, and the blade surface pressure load P N is the blade load obtained at the Nth time; where N is the number of cycles and N is a natural number; Step S200: Based on the blade three-dimensional model C N As well as structural ply information, create CAE structural simulation analysis model F N , the structural simulation analysis model F N The structural simulation analysis model constructed for the Nth time; the blade surface pressure load P N As a load applied to the CAE model F N Calculate the blade tip deformation DT N ; The blade tip deformation DT N is the deformation of the blade tip at the Nth time; Step S300: Determine whether the relative deformation ΔDT of the blade tip satisfies a threshold value less than or equal to the set threshold value. If so, output the shape C. N+1 If not, the calculation does not converge, and the iteration continues to return to step S100; if not, the calculation converges and the final load and tip deflection of the blade are output.

2. The fluid-structure coupling analysis method for wind turbine blades according to claim 1, characterized in that: In step S2, the fan flow field is calculated using CFD simulation software. A CFD flow field simulation analysis model is created based on the original three-dimensional model C0 of the blade and the flow field boundary conditions to calculate the blade surface load pressure load P0.

3. The fluid-structure coupling analysis method for wind turbine blades according to claim 1, characterized in that: In step S2, CAE structural analysis software is used to calculate the blade structural deformation, and a CAE structural simulation analysis model F0 is created based on the original three-dimensional model C0 of the blade and the structural ply information; The blade surface load pressure load P0 is loaded into the CAE model F0 as a load, and the blade tip deformation DT0 is calculated.

4. The fluid-structure coupling analysis method for wind turbine blades according to claim 1, characterized in that: In step S3, it is determined whether the relative deformation ΔDT of the blade tip satisfies or is less than or equal to a set threshold. If so, the shape C1 is output; if not, an iterative solution is performed.

5. The fluid-structure coupling analysis method for wind turbine blades according to claim 4, characterized in that: The set threshold is 2%-7%.

6. The fluid-structure coupling analysis method for wind turbine blades according to claim 5, characterized in that: The set threshold is 5%.

7. The fluid-structure coupling analysis method for wind turbine blades according to any one of claims 1 to 3, characterized in that: The original shape parameters of the blade include chord length, twist angle, pre-bend, relative thickness, and pitch axis position.

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