Blade deformation evaluation method, electronic device, and storage medium

Abstract

The application relates to the technical field of wind turbine units, and particularly provides a blade deformation evaluation method, an electronic device and a storage medium, and aims to solve the problems of existing blade deformation evaluation methods, such as complex calculation and limited precision. To this end, the blade deformation evaluation method comprises the following steps: constructing an aeroelastic model considering tip loss, wherein the aeroelastic model comprises an aerodynamic model and a structural model; constructing a tip loss coefficient database; determining initial aerodynamic force and initial blade deformation corresponding to the initial aerodynamic force based on the aeroelastic model; determining corrected aerodynamic force based on the initial aerodynamic force, the initial blade deformation and the tip loss coefficient database; and evaluating the deformation state of the blade based on the initial aerodynamic force and the corrected aerodynamic force. Through reasonable modeling and analysis, the application can accurately identify the deformation state of the blade under different wind speed conditions, and optimize the design and operation parameters of the blade.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wind turbine, in particular to a blade deformation evaluation method, an electronic device and a storage medium. BACKGROUND

[0002] With the development trend of large-scale wind turbine, the aspect ratio of the blade is significantly increased, and its structural flexibility is also increased. The flexibility of the blade makes it prone to large bending and torsional deformation under strong wind and turbulent conditions. Such dynamic response (including bending, torsion and vibration) not only directly affects the aerodynamic efficiency of the blade, but also reduces its structural stability and service life. In addition, deformation may cause structural fatigue and even failure, resulting in serious safety hazards and economic losses. Therefore, how to accurately evaluate the deformation characteristics of flexible blades under different operating conditions has become a key problem in the design and optimization of wind turbines. At present, there are some deformation evaluation methods for flexible blades, but these methods are often complex in calculation, limited in precision, and difficult to be popularized and applied in practical engineering.

[0003] Correspondingly, there is a need for a new blade deformation evaluation scheme to solve the above problems. SUMMARY

[0004] In order to overcome the above defects, the present application is proposed to solve or at least partially solve the technical problems of the existing blade deformation evaluation method which is complex in calculation and limited in precision.

[0005] In a first aspect, a blade deformation evaluation method is provided, the method comprising: constructing an aeroelastic model considering tip loss, the aeroelastic model comprising an aerodynamic model and a structural model; constructing a tip loss coefficient database; determining an initial aerodynamic force and an initial blade deformation corresponding to the initial aerodynamic force based on the aeroelastic model; determining a corrected aerodynamic force based on the initial aerodynamic force, the initial blade deformation and the tip loss coefficient database; and evaluating a deformation state of the blade based on the initial aerodynamic force and the corrected aerodynamic force.

[0006] In one technical solution of the above blade deformation evaluation method, the construction of the aeroelastic model considering tip loss comprises: introducing axial and tangential induction factors based on the blade element momentum theory, and combining a tip loss factor to correct the momentum theory to construct the aerodynamic model; simplifying the blade into a beam element, and constructing a structural model based on the geometrically exact beam theory, material parameters and structural parameters of the blade; and coupling the aerodynamic model and the structural model to obtain the aeroelastic model considering tip loss.

[0007] In a technical solution of the blade deformation evaluation method, the axial induction factor and the tangential induction factor are introduced based on the blade momentum theorem, the momentum theorem is corrected by combining with the tip loss factor, and an aerodynamic model is constructed, including: introducing the axial induction factor and the tangential induction factor to describe the velocity reduction of airflow through the wind wheel; establishing a velocity synthesis relationship, the velocity synthesis relationship includes the relationship between the free flow velocity, the wind wheel speed, the axial induction factor and the tangential induction factor; determining the relationship among the inflow angle, the attack angle and the pitch angle; calculating the blade element micro-element lift and the blade element micro-element drag based on the airfoil lift coefficient and the airfoil drag coefficient; determining the normal force and the tangential force acting on the blade element based on the blade element micro-element lift and the blade element micro-element drag; determining the calculation formula of the thrust and the torque acting on the blade element based on the normal force and the tangential force acting on the blade element; based on the momentum theorem, the tip loss factor is applied to the thrust and torque equation of the momentum theorem to obtain a corrected momentum equation; based on the calculation formula of the thrust and the torque acting on the blade element and the determined axial induction factor and the tangential induction factor, the aerodynamic model is obtained.

[0008] In a technical solution of the blade deformation evaluation method, the axial induction factor and the tangential induction factor are introduced based on the blade momentum theorem, the axial induction factor and the tangential induction factor are introduced based on the blade momentum theorem, the momentum theorem is corrected by combining with the tip loss factor, and an aerodynamic model is constructed, including: introducing the axial induction factor and the tangential induction factor to describe the velocity reduction of airflow through the wind wheel; establishing a velocity synthesis relationship, the velocity synthesis relationship includes the relationship between the free flow velocity, the wind wheel speed, the axial induction factor and the tangential induction factor; determining the relationship among the inflow angle, the attack angle and the pitch angle; calculating the blade element micro-element lift and the blade element micro-element drag based on the airfoil lift coefficient and the airfoil drag coefficient; determining the normal force and the tangential force acting on the blade element based on the blade element micro-element lift and the blade element micro-element drag; determining the calculation formula of the thrust and the torque acting on the blade element based on the normal force and the tangential force acting on the blade element; based on the momentum theorem, the tip loss factor is applied to the thrust and torque equation of the momentum theorem to obtain a corrected momentum equation; based on the calculation formula of the thrust and the torque acting on the blade element and the determined axial induction factor and the tangential induction factor, the aerodynamic model is obtained.

[0009] In a technical solution of the blade deformation evaluation method, the axial induction factor and the tangential induction factor are introduced based on the blade momentum theorem, the axial induction factor and the tangential induction factor are introduced based on the blade momentum theorem, the momentum theorem is corrected by combining with the tip loss factor, and an aerodynamic model is constructed, including: introducing the axial induction factor and the tangential induction factor to describe the velocity reduction of airflow through the wind wheel; establishing a velocity synthesis relationship, the velocity synthesis relationship includes the relationship between the free flow velocity, the wind wheel speed, the axial induction factor and the tangential induction factor; determining the relationship among the inflow angle, the attack angle and the pitch angle; calculating the blade element micro-element lift and the blade element micro-element drag based on the airfoil lift coefficient and the airfoil drag coefficient; determining the normal force and the tangential force acting on the blade element based on the blade element micro-element lift and the blade element micro-element drag; determining the calculation formula of the thrust and the torque acting on the blade element based on the normal force and the tangential force acting on the blade element; based on the momentum theorem, the tip loss factor is applied to the thrust and torque equation of the momentum theorem to obtain a corrected momentum equation; based on the calculation formula of the thrust and the torque acting on the blade element and the determined axial induction factor and the tangential induction factor, the aerodynamic model is obtained.

[0010] In a technical solution of the blade deformation evaluation method, the axial induction factor and the tangential induction factor are introduced based on the blade momentum theorem, the axial induction factor and the tangential induction factor are introduced based on the blade momentum theorem, the momentum theorem is corrected by combining with the tip loss factor, and an aerodynamic model is constructed, including: introducing the axial induction factor and the tangential induction factor to describe the velocity reduction of airflow through the wind wheel; establishing a velocity synthesis relationship, the velocity synthesis relationship includes the relationship between the free flow velocity, the wind wheel speed, the axial induction factor and the tangential induction factor; determining the relationship among the inflow angle, the attack angle and the pitch angle; calculating the blade element micro-element lift and the blade element micro-element drag based on the airfoil lift coefficient and the airfoil drag coefficient; determining the normal force and the tangential force acting on the blade element based on the blade element micro-element lift and the blade element micro-element drag; determining the calculation formula of the thrust and the torque acting on the blade element based on the normal force and the tangential force acting on the blade element; based on the momentum theorem, the tip loss factor is applied to the thrust and torque equation of the momentum theorem to obtain a corrected momentum equation; based on the calculation formula of the thrust and the torque acting on the blade element and the determined axial induction factor and the tangential induction factor, the aerodynamic model is obtained.

[0011] In a technical solution of the blade deformation evaluation method, the determining of the corrected aerodynamic force based on the initial aerodynamic force, the initial blade deformation and the tip loss coefficient database comprises: determining the tip loss coefficient corresponding to the initial blade deformation based on the initial blade deformation and the tip loss coefficient database by using a linear interpolation method; and determining the corrected aerodynamic force based on the tip loss coefficient corresponding to the initial blade deformation and the aerodynamic model.

[0012] In a technical solution of the blade deformation evaluation method, the determining of the corrected aerodynamic force based on the initial aerodynamic force, the initial blade deformation and the tip loss coefficient database comprises: determining the tip loss coefficient corresponding to the initial blade deformation based on the initial blade deformation and the tip loss coefficient database by using a linear interpolation method; and determining the corrected aerodynamic force based on the tip loss coefficient corresponding to the initial blade deformation and the aerodynamic model.

[0013] In a second aspect, an electronic device is provided, comprising at least one processor; and a memory connected with the at least one processor in communication; wherein the memory has stored therein a computer program, which, when executed by the at least one processor, implements the method of any one of the technical solutions of the blade deformation evaluation method.

[0014] In a third aspect, a computer readable storage medium is provided, which has stored therein a plurality of program codes, the program codes being adapted to be loaded and run by a processor to execute the method of any one of the technical solutions of the blade deformation evaluation method.

[0015] The one or more technical solutions of the present application have at least one or more of the following beneficial effects:

[0016] The blade deformation evaluation method provided by the present application comprises: constructing an aeroelastic model considering tip loss, the aeroelastic model comprising an aerodynamic model and a structural model; constructing a tip loss coefficient database; determining an initial aerodynamic force and an initial blade deformation corresponding to the initial aerodynamic force based on the aeroelastic model; determining a corrected aerodynamic force based on the initial aerodynamic force, the initial blade deformation and the tip loss coefficient database; and evaluating a deformation state of a blade based on the initial aerodynamic force and the corrected aerodynamic force. The present application can accurately identify the deformation state of a blade under different wind speed conditions by reasonable modeling and analysis, and realize high-precision deformation evaluation. The present application is suitable for the design and operation evaluation of large-aspect-ratio and long-flexible blades, and provides reliable data support for optimizing the design and operation parameters of blades. BRIEF DESCRIPTION OF DRAWINGS

[0017] The disclosure of the present application will become more fully understood from the detailed description given herein below, and appended claims, accompanied by the accompanying drawings. It is to be understood that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the application, for which reference should be made to the appended claims. In the drawings, in which like reference numerals refer to similar elements throughout the several views:

[0018] Figure 1 is a schematic diagram of the main steps of a blade deformation evaluation method according to an embodiment of the present application;

[0019] Figure 2 is a schematic diagram of the velocity synthesis relationship and aerodynamic force under the condition of blade element rotation according to an embodiment of the present application;

[0020] Figure 3 is a schematic diagram of the beam deformation state according to an embodiment of the present application;

[0021] Figure 4 is a schematic diagram of the blade simplified as a beam model according to an embodiment of the present application;

[0022] Figure 5 is a schematic diagram of the detailed flow of the blade deformation evaluation according to an embodiment of the present application;

[0023] Figure 6 is a schematic diagram of the main structure of an electronic device according to an embodiment of the present application.

[0024] Reference Signs:

[0025] 11: memory; 12: processor. DETAILED DESCRIPTION

[0026] Some embodiments of the present application will now be described with reference to the drawings. It will be understood by those skilled in the art that these embodiments are merely for the purpose of illustrating the technical principles of the present application, and are not intended to limit the scope of protection of the present application.

[0027] In the description of the present application, "module", "processor" can include hardware, software or a combination of both. A module can include hardware circuit, various suitable sensors, communication port, memory, and can also include software part such as program code, and can be a combination of software and hardware. The processor can be a central processor, microprocessor, image processor, digital signal processor or any other suitable processor. The processor has data and / or signal processing function. The processor can be implemented in software, hardware or a combination of both. The computer readable storage medium includes any suitable medium that can store program code, such as magnetic disk, hard disk, optical disk, flash memory, read-only memory, random access memory, etc. The term "A and / or B" means all possible combinations of A and B, such as only A, only B or A and B. The term "at least one of A or B" or "at least one of A and B" has similar meaning as "A and / or B", which can include only A, only B or A and B. The singular form of the term "one", "this" can also include plural forms.

[0028] With the development trend of large-scale wind turbine, the aspect ratio of the blade increases significantly, and its structural flexibility also increases. The flexibility of the blade makes it prone to large bending and torsional deformation under strong wind and turbulent conditions. This dynamic response (including bending, torsion and vibration) not only directly affects the aerodynamic efficiency of the blade, but also reduces its structural stability and service life. In addition, deformation may cause structural fatigue and even failure, resulting in serious safety hazards and economic losses. Therefore, how to accurately evaluate the deformation characteristics of flexible blades under different operating conditions has become a key problem in the design and optimization of wind turbines. At present, there are some deformation evaluation methods for flexible blades, but these methods are often complex in calculation, limited in precision, and difficult to be applied in practical engineering.

[0029] Therefore, the present application provides a blade deformation evaluation method, which realizes high-precision deformation evaluation through the following steps: constructing an aeroelastic model considering tip loss, including an aerodynamic model and a structural model; constructing a tip loss coefficient database; determining the initial aerodynamic force and the corresponding initial blade deformation based on the aeroelastic model; determining the corrected aerodynamic force in combination with the initial aerodynamic force, the initial blade deformation and the tip loss coefficient database; and evaluating the deformation state of the blade based on the initial aerodynamic force and the corrected aerodynamic force. Through reasonable modeling and analysis, the present application can accurately identify the deformation state of the blade under different wind speed conditions, realizing high-precision deformation evaluation. It is suitable for the design and operation evaluation of large-aspect-ratio and long-flexible blades, and provides reliable data support for optimizing the design and operation parameters of the blade.

[0030] Referring to the accompanying Figure 1 , Figure 1 is the main step flow diagram of the blade deformation evaluation method according to an embodiment of the present application. As shown inFigure 1 As shown, the blade deformation evaluation method in the embodiment is suitable for deformation evaluation of a flexible blade, and mainly includes the following steps S101 to S105.

[0031] Step S101: constructing an aeroelastic model considering tip loss, the aeroelastic model including an aerodynamic model and a structural model.

[0032] Step S102: constructing a tip loss coefficient database.

[0033] Step S103: determining an initial aerodynamic force and an initial blade deformation corresponding to the initial aerodynamic force based on the aeroelastic model.

[0034] Step S104: determining a corrected aerodynamic force based on the initial aerodynamic force, the initial blade deformation and the tip loss coefficient database.

[0035] Step S105: evaluating a deformation state of the blade based on the initial aerodynamic force and the corrected aerodynamic force.

[0036] Based on the method described in the above steps S101 to S105, the application realizes bidirectional feedback of aerodynamic load and structural deformation by coupling the aerodynamic model and the structural model, significantly improving the deformation prediction accuracy. By introducing the tip loss factor, the problem of aerodynamic performance decline caused by tip vortex shedding is accurately corrected, making the aerodynamic load calculation closer to the actual working condition. In addition, the closed-loop iterative process of aerodynamic force, structural deformation and corrected aerodynamic force is adopted to dynamically adjust the relationship between aerodynamic load and deformation, which can accurately evaluate the deformation state of the blade.

[0037] The above steps S101 to S105 will be further described below.

[0038] For step S101, in an embodiment, the construction of the aeroelastic model considering tip loss includes: based on the blade element momentum theory, introducing axial and tangential induction factors, and combining the tip loss factor to correct the momentum theory, constructing the aerodynamic model; simplifying the blade into a beam element, based on the geometric precise beam theory, material parameters and structural parameters of the blade, constructing the structural model; coupling the aerodynamic model and the structural model to obtain the aeroelastic model considering tip loss.

[0039] The blade element momentum theory (BEM) is the core theory of wind turbine aerodynamic performance analysis, which combines momentum theory and blade element theory, and is used to calculate load distribution, thrust and power on the wind turbine blade and other parameters.

[0040] Geometrically Exact Beam Theory (GEBT) is a theoretical framework for describing the mechanical behavior of slender structures (such as beams, wings, etc.) under geometrically nonlinear conditions such as large deformation, large rotation, etc. Its core feature is to capture nonlinear deformation through precise mathematical description, avoiding the simplifying assumptions of traditional linear beam theory.

[0041] Specifically, when constructing the aerodynamic model based on the blade element momentum theory (BEM), the axial and tangential induction factors are used to quantify the velocity reduction effect of the airflow passing through the wind turbine, and the blade tip loss factor is used to modify the momentum theorem, ultimately achieving high-precision calculation of aerodynamic force.

[0042] Based on the Geometrically Exact Beam Theory (GEBT), the blade is simplified as a beam element, and the material and structural parameters of the blade are defined. The nonlinear motion control equation of the blade is constructed through finite element discretization to obtain the structural model.

[0043] In one embodiment, based on the blade element momentum theory, the axial and tangential induction factors are introduced, and the blade tip loss factor is used to modify the momentum theorem to construct the aerodynamic model, including: introducing the axial and tangential induction factors to describe the velocity reduction of the airflow passing through the wind turbine; establishing a velocity synthesis relationship, which includes the relationship between the free flow velocity, the wind turbine speed, the axial and tangential induction factors; determining the relationship between the inflow angle, the attack angle and the pitch angle; calculating the blade element micro-element lift and blade element micro-element drag based on the airfoil lift coefficient and airfoil drag coefficient; determining the normal force and tangential force acting on the blade element based on the blade element micro-element lift and blade element micro-element drag; determining the calculation formula of the thrust and torque acting on the blade element based on the normal force and tangential force acting on the blade element; based on the momentum theorem, the blade tip loss factor is applied to the thrust and torque equation of the momentum theorem to obtain the modified momentum equation; based on the calculation formula of the thrust and torque acting on the blade element and the modified momentum equation, the axial and tangential induction factors are determined by iterative calculation; based on the calculation formula of the thrust and torque acting on the blade element and the determined axial and tangential induction factors, the aerodynamic model is obtained.

[0044] Specifically, the construction of the aerodynamic model is based on the following assumptions: the wind turbine is simplified as a planar disc, which is assumed to be composed of an infinite number of blades; the flow is uniform and steady, and the influence of air compression is ignored; the radial blade elements are independent of each other, there is no interaction force between the blade elements, and the radial flow of the flow field particles is ignored; the influence of wake-induced velocity is ignored.

[0045] When the airflow passes through the blade and the rotating plane of the wind turbine, its axial and tangential velocities will change, so the axial and tangential induction factors a and b are introduced to reflect the velocity reduction of the airflow passing through the wind turbine.

[0046] Referring to the drawings Figure 2 , Figure 2 is a schematic diagram of the velocity composition relationship and aerodynamic force under the condition of blade element rotation according to an embodiment of the present application. As shown in Figure 2 , the velocity composition relationship is expressed as:

[0047]

[0048] In the formula, V is the free flow speed; φ is the inflow angle; Ω is the wind wheel rotation speed; a is the axial induction factor; b is the tangential induction factor; and r is the radius at the blade position where the blade element is located.

[0049] The relationship among the inflow angle, the attack angle and the pitch angle is expressed as:

[0050] α = φ - β

[0051] In the formula, α is the attack angle; and β is the pitch angle.

[0052] Based on the blade chord length, the air density, the airfoil lift coefficient, the airfoil drag coefficient, the flow resultant speed, the blade element microelement lift and the blade element microelement drag are calculated, and the calculation formula of the blade element microelement lift is:

[0053]

[0054] The calculation formula of the blade element microelement drag is:

[0055]

[0056] In the formula, ρ is the air density, W is the flow resultant speed, C is the chord length, C L is the airfoil lift coefficient, C D is the airfoil drag coefficient, and r is the radius at the blade position where the blade element is located.

[0057] The lift and the drag borne by the blade element microelement are decomposed into the directions of the wind wheel rotation plane and the direction perpendicular to the wind wheel rotation plane, to obtain the normal force F n and the tangential force F t acting on the blade element.

[0058] The calculation formula of the normal force F n is:

[0059]

[0060] The calculation formula of the tangential force F t is:

[0061]

[0062] In the formula, C n is the normal force coefficient, Ct is the tangential force coefficient, denoted as:

[0063] C n = C L cosφ + C D sinφ

[0064] C t = C L sinφ - C D cosφ

[0065] Based on the normal force and tangential force acting on the blade element, the calculation formula of the thrust and torque of the blade element at a distance r from the center of the wind wheel is determined, denoted as:

[0066]

[0067] wherein dT 叶素 is the thrust of the blade element, dM 叶素 is the torque of the blade element, and B is the number of blades.

[0068] According to the momentum theorem, the thrust and torque of the micro-element ring with a width of dr acting on the wind wheel radius r are:

[0069] dT 动量 = 4πρV 2 (1-a)ar dr

[0070] dM 动量 = 4πρVΩ(1-a)br 3 dr

[0071] However, in actual situations, due to the limited number of fan blades, the blade disc will produce tip vortex shedding phenomenon, and part of the air will flow around the lower surface of the blade to the upper surface, resulting in secondary flow of inflow near the blade tip. The existence of such tip vortex makes the aerodynamic performance near the blade tip significantly decrease, and at this time the blade element momentum theory cannot accurately calculate the aerodynamic force near the blade tip. The energy loss caused by tip vortex shedding will reduce the output power of the wind wheel. In order to make up for the calculation error caused by tip vortex shedding, a Prandtl tip loss factor F is introduced, and the error caused by tip loss can be represented by the tip loss factor F:

[0072]

[0073] Then the tip loss factor F acts on the thrust and torque equation of the momentum theorem, and the modified momentum equation is obtained:

[0074] dT 动量 = 4πρV 2 (1-a)ar F dr

[0075] dM 动量= 4πρVΩ(1 - a)br 3 Fdr

[0076] Based on the calculation formula of the thrust and torque on the blade element and the corrected momentum equation, the axial and tangential induction factors are determined by iterative calculation, specifically, dT 叶素 = dT 动量 , dM 叶素 = dM 动量 , so that the axial and tangential induction factors are:

[0077]

[0078] In the calculation, first, the axial and tangential induction factors a and b are initialized, assuming a = b = 0; then the inflow angle φ is calculated according to the velocity synthesis relationship. After obtaining the inflow angle, the corresponding attack angle of the airfoil is obtained, and the lift and drag coefficients under the corresponding attack angle are obtained by referring to the airfoil data table, so that the corresponding normal force coefficient and tangential force coefficient are obtained. The normal force coefficient, tangential force coefficient and inflow angle are substituted into the above a, b solving formula to obtain the axial and tangential induction factors a and b, thus completing one iteration process. Repeat this process until a and b converge. Then, the converged a and b values are substituted back into the calculation formula of the thrust and torque on the blade element, so that the aerodynamic force on the blade element is obtained. The aerodynamic force on the blade element is integrated along the blade span to obtain the aerodynamic load on the blade and the wind wheel.

[0079] In one embodiment, the blade is simplified as a beam element, and a structural model is constructed based on the geometrically exact beam theory, material parameters and structural parameters of the blade.

[0080] Specifically, the blade is simplified as a beam element, and the deformation state of the beam is as shown in Figure 3 .

[0081] The motion equation of the geometrically exact beam is based on the law of conservation of momentum, and is expressed as:

[0082]

[0083] The first formula is the linear momentum conservation equation of the beam, and the second formula is the relationship between the angular momentum change of the beam and the internal and external moments.

[0084] In the formula, h is the linear momentum in the inertial coordinate system, g is the angular momentum in the inertial coordinate system; F is the cross-sectional force of the beam; M is the moment of the beam; u is the linear displacement of a point on the reference line; x0 is the position vector of the point along the reference line of the beam; f and m are the distributed force and moment applied to the beam structure. The symbol F' represents the derivative with respect to the axial displacement, the derivative with respect to time. The wavy line operator The skew-symmetric tensor corresponding to a given vector is defined. The superscript (·) denotes the derivative with respect to time. T is the transpose operator.

[0085] The constitutive relations between the velocity and momentum, one-dimensional strain measurements and cross-sectional results are established. The constitutive equations relate the kinematic variables to the mechanical response:

[0086]

[0087] where M is the 6x6 cross-sectional mass matrix, C is the 6x6 cross-sectional stiffness matrix; ε and k are the one-dimensional strain and curvature, respectively; ω is the angular velocity vector defined by the rotation tensor R, where ω = axial(RR T ), the vector a is associated with the second-order tensor A whose components are defined as:

[0088]

[0089] The one-dimensional strain ε and curvature k can be expressed as:

[0090]

[0091] where K = axial[(RR0)'(RR0) T ], K is the cross-sectional curvature vector decomposed in the inertial basis, R is the current rotation tensor, R0 is the initial rotation tensor, (RR0) T is the transpose matrix of (RR0), li is the unit vector along the s-axis direction in the inertial basis, x'0 is the derivative of the initial position vector with respect to s-axis, u' is the derivative of the displacement vector with respect to s-axis. The above equations together constitute the mathematical description of the elastic problem of the geometrically exact beam.

[0092] The nonlinear control motion equations of the beam are solved iteratively by the Newton-Raphson method, and the beam element is discretized using the Legendre spectral finite element method. The linearized form of the nonlinear motion control equations is as follows:

[0093]

[0094] where, is the element mass matrix; is the rotation matrix; is the stiffness matrix; is the generalized element acceleration; is the generalized velocity, is the generalized nodal displacement array increment; denotes the external applied load; denotes the element force.

[0095] The time integration is calculated using the generalized alpha time integrator:

[0096] |ΔU (i)T ( t+Δt R- t+Δt F (i-1) )|≤|ε E [ΔU (1)T ( t+Δt R- t F)]|

[0097] where ΔU is the increment of displacement vector; R is the externally applied nodal load vector; F is the nodal force vector corresponding to the internal element stress; ε E is the preset energy tolerance; the upper index on the left side of the variable represents the time value, indicating that it is in dynamic analysis, and the upper index on the right side represents the iteration number.

[0098] The three-dimensional rotation of the beam section in deformation is described by Wiener-Milenkovic parameters, which is in the form of:

[0099]

[0100] where, is the rotation angle, and n is the unit vector of the rotation axis.

[0101] The deformation percentage is used to quantify the deformation degree of the blade, which is expressed as:

[0102]

[0103] where ω is the tip deformation, and l is the total length of the blade.

[0104] The blade is simplified as a beam model as shown in Figure 4 By simplifying the complex blade geometry into a beam model, combining the above theory, inputting the corresponding structural parameters, and using the Legendre spectral finite element to realize the numerical implementation of the node freedom, the trapezoidal integration method is used to model the wind turbine blade with a single element, and the Wiener-Milenkovic parameter is used to represent the three-dimensional rotation to obtain the linear displacement and angular displacement of each node of the blade. Secondly, the Newton-Raphson method is used to solve the nonlinear motion control equation, and after linearization, the generalized alpha time integrator is used to judge whether the equation converges.

[0105] For step S102, in one embodiment, the construction of the tip loss coefficient database comprises: determining the aerodynamic force data corresponding to a plurality of preset deformation amplitudes by using a CFD numerical simulation method; calculating the tip loss coefficient under an arbitrary deformation amplitude based on the aerodynamic force data under a plurality of preset deformation amplitudes by using a linear interpolation method; and associating the tip loss coefficient under the arbitrary deformation amplitude with the corresponding deformation amplitude to construct the tip loss coefficient database.

[0106] Specifically, the aerodynamic force data of the blade under multiple preset deformation amplitudes is obtained by CFD numerical simulation, and the CFD numerical simulation is solved to calculate the aerodynamic force corresponding to the multiple preset deformation amplitudes.

[0107] The deformation amplitude of the blade may not be equal to the data used in the simulation, which requires a continuous tip loss coefficient to describe the aerodynamic characteristics under any deformation amplitude. For this purpose, a linear interpolation formula is used to calculate the tip loss coefficient F extra under any deformation amplitude according to the data obtained by CFD simulation. The interpolation method can generate a smooth curve between data points, ensuring the continuity and accuracy of the loss coefficient in the entire deformation range, so that the aerodynamic performance of the actual blade under different deformations can be better simulated.

[0108] Suppose the tip loss coefficients F i and F i+1 corresponding to the adjacent two deformation amplitude points ω extra(i) and ω extra(i+1) are known, then for any deformation amplitude ω in the interval (ω i , ω i+1 ), the interpolation formula is:

[0109]

[0110] where ω is any deformation amplitude of the tip deformation deflection in the interval (ω i , ω i+1 ).

[0111] The tip loss coefficient under any deformation amplitude obtained is associated with the corresponding deformation amplitude to construct a tip loss coefficient database.

[0112] In one embodiment, the CFD numerical simulation method is used to determine the aerodynamic force data corresponding to multiple preset deformation amplitudes, including: based on multiple preset deformation amplitudes, generating corresponding geometric models and dividing CFD grids; performing CFD numerical simulation on multiple preset deformation amplitudes to determine the aerodynamic force data corresponding to multiple preset deformation amplitudes.

[0113] Specifically, the multiple preset deformation amplitudes can be set as η1=0%, η2=5%, η3=10%, η4=15%, and η5=20%. The geometric model of the blade under each preset deformation amplitude is generated, and the CFD calculation grid is drawn. The grid model is subjected to CFD numerical simulation to calculate the aerodynamic force of the blade corresponding to each preset deformation amplitude. The aerodynamic force of the deformed blade is compared with the aerodynamic force of the undeformed blade to obtain an additional tip loss coefficient, defined as F extra , which is associated with the preset deformation amplitude.

[0114] Regarding step S103, in one embodiment, determining the initial aerodynamic force and the initial blade deformation corresponding to the initial aerodynamic force based on the aeroelastic model includes: calculating the initial aerodynamic force when the blade is not deformed using an aerodynamic model; inputting the initial aerodynamic force into the structural model to determine the initial blade deformation corresponding to the initial aerodynamic force.

[0115] Specifically, the initial aerodynamic force F1 when the blade is undeformed is calculated using an aerodynamic model, and the initial aerodynamic force F1 is input into the structural model to obtain the initial deformation deflection w1 of the blade under the initial aerodynamic force F1, which is used as the initial blade deformation amount corresponding to the initial aerodynamic force.

[0116] Regarding step S104, in one embodiment, determining the corrected aerodynamic force based on the initial aerodynamic force, the initial blade deformation, and the tip loss coefficient database includes: determining the tip loss coefficient corresponding to the initial blade deformation using a linear interpolation method based on the initial blade deformation and the tip loss coefficient database; and determining the corrected aerodynamic force based on the tip loss coefficient corresponding to the initial blade deformation and the aerodynamic model.

[0117] Specifically, after the blade deforms, the initial aerodynamic force F1 acting on the blade will change, and the aerodynamic force needs to be reassessed.

[0118] Based on the initial blade deformation and combined with an additional tip loss database, an interpolation method is used to obtain the tip loss coefficient F corresponding to the initial blade deformation. extra And based on the tip loss coefficient F corresponding to the initial blade deformation. extra Thus, the corrected aerodynamic force F2 is obtained.

[0119] Specifically:

[0120] Based on the tip loss coefficient F corresponding to the initial blade deformation extra Calculate the new values ​​of axial induction factor a and tangential induction factor b:

[0121]

[0122] Where, F(r)=F extra *F, F(r) is the tip loss coefficient F extra The product of the leaf tip loss factor F.

[0123] Compare the new values ​​of a and b with the values ​​of the previous iteration. If the new values ​​of a and b are within the error range compared with the values ​​of the previous iteration, the new values ​​can be adopted; otherwise, the new values ​​of a and b are used as the values ​​of the previous iteration, the new values ​​of axial induction factor a and tangential induction factor b are recalculated, and the iteration continues.

[0124] Based on the determined axial induction factor a and tangential induction factor b, the thrust and torque formula of the micro-element ring is substituted back, so as to obtain the aerodynamic force on the blade element. The aerodynamic force on the blade element is integrated along the blade span to obtain the aerodynamic load on the blade and the wind wheel, and the corrected aerodynamic force F2 is obtained.

[0125] For step S105, in one embodiment, the evaluation of the deformation state of the blade based on the initial aerodynamic force and the corrected aerodynamic force comprises: calculating the difference between the corrected aerodynamic force and the initial aerodynamic force, judging whether the difference is within a preset threshold range, if yes, determining the deformation state of the blade based on the blade deformation amount corresponding to the corrected aerodynamic force; otherwise, re-determining the corrected aerodynamic force.

[0126] Specifically, the corrected aerodynamic force F2 is compared with the initial aerodynamic force F1. If the difference between the initial aerodynamic force and the corrected aerodynamic force is outside the preset threshold range, re-iteration is continued to update the blade aerodynamic force. Through the iteration, the deformation state of the wind power blade under actual operating conditions is obtained.

[0127] If the difference between the initial aerodynamic force and the corrected aerodynamic force is within the preset threshold range, the blade deformation amount corresponding to the corrected aerodynamic force (the blade deformation amount of the current iteration step) is taken as the final deformation state of the blade.

[0128] Referring to FIG. 8, Figure 5 Figure 5 FIG. 8 is a detailed flowchart of the blade deformation evaluation according to an embodiment of the present application. As shown in FIG. 8, in the embodiment, the blade deformation evaluation method comprises the following steps: Figure 5

[0129] Step S201, constructing an aeroelastic model considering tip loss, the aeroelastic model comprising an aerodynamic model and a structural model;

[0130] Step S202, constructing a tip loss coefficient database;

[0131] Step S203, obtaining wind load, determining initial aerodynamic force based on the aerodynamic model, and determining initial blade deformation amount based on the structural model;

[0132] Step S204, determining corrected aerodynamic force based on the initial blade deformation amount and in combination with the tip loss coefficient database;

[0133] Step S205, calculating the difference between the corrected aerodynamic force and the initial aerodynamic force, judging whether it is within a preset threshold range, if yes, judging convergence to obtain the final deformation state of the blade; otherwise, re-iterating to continue updating the blade aerodynamic force.

[0134] ​​The present application establishes an aeroelastic model of a wind turbine blade based on the blade element momentum theory (BEM) and the geometrically exact beam theory (GEBT) and introduces an additional tip loss coefficient, and through reasonable modeling and analysis techniques, the aeroelastic model is used to evaluate the deformation state of the flexible blade under different wind speed conditions, and to optimize the design and operation parameters of the blade.

[0135] It should be noted that, although the above embodiments describe the steps in a specific order, those skilled in the art can understand that, in order to achieve the effects of the present application, the different steps do not necessarily have to be executed in such an order, and they can be executed simultaneously (in parallel) or in other orders, and these adjusted schemes are equivalent to the technical schemes described in the present application, and thus will also fall within the protection scope of the present application.

[0136] Those skilled in the art can understand that all or part of the processes in the method of the above embodiment can also be completed by a computer program instructing related hardware, and the computer program can be stored in a computer readable storage medium, and the computer program can implement the steps of each method embodiment when executed by a processor. The computer program includes computer program code, which can be in the form of source code, object code, executable files or some intermediate forms, etc. The computer readable storage medium can include any entity or device, medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory, random access memory, electrical carrier signal, telecommunication signal and software distribution medium, etc. that can carry the computer program code.

[0137] Another aspect of the present application also provides an electronic device.

[0138] Referring to the accompanying Figure 6 , Figure 6 The memory 11 and the processor 12 are communicatively connected through a bus, as shown in the example in the accompanying drawings. In an embodiment of an electronic device according to the present application, the electronic device can include at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores a computer program, and the computer program is executed by the at least one processor to implement the blade deformation evaluation method described in any of the above embodiments.

[0139] Another aspect of the present application also provides a computer readable storage medium.

[0140] In an embodiment of the computer readable storage medium according to the present application, the computer readable storage medium can be configured to store a program of the blade deformation evaluation method of the above-mentioned method embodiments, which can be loaded and run by the processor to implement the above-mentioned blade deformation evaluation method. For the convenience of illustration, only the parts related to the embodiments of the present application are shown, and the specific technical details not disclosed are referred to the method part of the embodiments of the present application. The computer readable storage medium can be a storage device formed by various electronic devices, and optionally, the computer readable storage medium in the embodiments of the present application is a non-transitory computer readable storage medium.

[0141] So far, the technical solution of the present application has been described in combination with one embodiment shown in the drawings, but those skilled in the art can easily understand that the protection scope of the present application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to the related technical features without departing from the principles of the present application, and the technical solutions after these changes or replacements will fall within the protection scope of the present application.

Claims

1. A method of evaluating blade deformation, characterized by, The method comprises: constructing a aeroelastic model considering tip loss, the aeroelastic model comprising an aerodynamic model and a structural model; associating tip loss coefficients at any deformation amplitude with corresponding deformation amplitudes by using a CFD numerical simulation method to construct a tip loss coefficient database; determining an initial aerodynamic force and an initial blade deformation corresponding to the initial aerodynamic force based on the aeroelastic model; determining a corrected aerodynamic force based on the initial aerodynamic force, the initial blade deformation and the tip loss coefficient database; evaluating a deformation state of the blade based on the initial aerodynamic force and the corrected aerodynamic force.

2. The leaf deformation evaluation method according to claim 1, characterized in that, The aeroelastic model considering tip loss comprises: introducing axial and tangential induction factors based on the blade element momentum theory, and combining a tip loss factor to correct the momentum theory to construct an aerodynamic model; simplifying the blade into a beam element, and constructing a structural model based on a geometrically accurate beam theory, material parameters and structural parameters of the blade; coupling the aerodynamic model and the structural model to obtain the aeroelastic model considering tip loss.

3. The leaf deformation evaluation method according to claim 2, characterized in that, The aerodynamic model is constructed by introducing axial and tangential induction factors based on the blade element momentum theory, and combining a tip loss factor to correct the momentum theory, comprising: introducing axial and tangential induction factors to describe the velocity reduction of airflow through the wind wheel; establishing a velocity synthesis relationship, the velocity synthesis relationship comprising a relationship between free flow velocity, wind wheel speed, axial and tangential induction factors; determining a relationship between inflow angle, angle of attack and pitch angle; calculating blade element lift and blade element drag based on airfoil lift coefficient and airfoil drag coefficient; determining normal force and tangential force acting on the blade element based on the blade element lift and the blade element drag; determining calculation formulas of thrust and torque acting on the blade element based on the normal force and the tangential force acting on the blade element; applying a tip loss factor to thrust and torque equations of the momentum theory based on the momentum theory to obtain a corrected momentum equation; iteratively calculating and determining axial and tangential induction factors based on the calculation formulas of thrust and torque acting on the blade element and the corrected momentum equation; obtaining the aerodynamic model based on the calculation formulas of thrust and torque acting on the blade element and the determined axial and tangential induction factors.

4. The leaf deformation evaluation method according to claim 1, characterized in that, The tip loss coefficient database is constructed by associating tip loss coefficients at any deformation amplitude with corresponding deformation amplitudes by using a CFD numerical simulation method, comprising: determining aerodynamic force data corresponding to a plurality of preset deformation amplitudes by using a CFD numerical simulation method; calculating tip loss coefficients at any deformation amplitude based on aerodynamic force data at a plurality of preset deformation amplitudes by using a linear interpolation method; associating the tip loss coefficients at any deformation amplitude with corresponding deformation amplitudes to construct a tip loss coefficient database.

5. The leaf deformation evaluation method according to claim 4, characterized in that, The aerodynamic force data corresponding to a plurality of preset deformation amplitudes are determined by using a CFD numerical simulation method, comprising: generating corresponding geometric models and dividing CFD grids based on a plurality of preset deformation amplitudes; determining aerodynamic force data corresponding to a plurality of preset deformation amplitudes by performing CFD numerical simulation on the plurality of preset deformation amplitudes.

6. The leaf deformation evaluation method according to claim 1, characterized in that, The determining, based on the aeroelastic model, of an initial aerodynamic force and an initial blade deformation corresponding to the initial aerodynamic force comprises: calculating, using the aeroelastic model, an initial aerodynamic force when the blade is not deformed; inputting the initial aerodynamic force into the structural model to determine an initial blade deformation corresponding to the initial aerodynamic force.

7. The leaf deformation evaluation method according to claim 1, characterized in that, The determining, based on the initial aerodynamic force, the initial blade deformation, and the tip loss coefficient database, of a corrected aerodynamic force comprises: determining, based on the initial blade deformation and the tip loss coefficient database, a tip loss coefficient corresponding to the initial blade deformation using a linear interpolation method; determining, based on the tip loss coefficient corresponding to the initial blade deformation and the aeroelastic model, a corrected aerodynamic force.

8. The leaf deformation evaluation method according to claim 1, characterized in that, The evaluating, based on the initial aerodynamic force and the corrected aerodynamic force, of a deformation state of the blade comprises: calculating a difference between the corrected aerodynamic force and the initial aerodynamic force, and determining whether the difference is within a preset threshold range; if yes, determining, based on a blade deformation corresponding to the corrected aerodynamic force, the deformation state of the blade; otherwise, re-determining the corrected aerodynamic force.

9. An electronic device comprising at least one processor and at least one memory adapted to store a plurality of program codes, characterized in that, The program code is adapted to be loaded and run by the processor to execute the blade deformation evaluation method of any one of claims 1 to 8.

10. A computer readable storage medium having stored therein a plurality of program codes, characterized in that, The program code is adapted to be loaded and run by the processor to execute the blade deformation evaluation method of any one of claims 1 to 8.

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