A simulation analysis method for rain erosion performance of wind turbine blade leading edge protective film

Abstract

This invention discloses a simulation analysis method for the rain erosion performance of the leading edge protective film of wind turbine blades, belonging to the field of wind turbine blade impact simulation technology. Based on the simulation of the impeller wind field, discrete phase simulation of raindrops is used to obtain the horizontal velocity of the raindrops, and the impact velocity is derived based on the simulation results and the vertical falling velocity of the raindrops. A finite element model of the leading edge protective film with a composite material matrix is ​​established using a layered approach, and the SPH method is used to simulate raindrop impact. By changing the raindrop diameter and raindrop impact velocity in the model, the rain erosion impact of the protective film under various operating conditions is simulated and analyzed. A water-covered impact model is established to analyze the buffering effect of surface water coverage. This invention obtains the actual raindrop impact conditions based on wind-driven rain simulation and establishes a locally accurate model of the blade, which can more efficiently and accurately simulate the rain erosion impact of the blade protective film, providing a reliable basis and effective data for the study of rain erosion of blade protective materials.

Description

Technical Field

[0001] The invention belongs to the technical field of wind turbine blade impact simulation, and in particular relates to a method for simulating and analyzing rain erosion performance of a leading edge protective film of a wind turbine blade. Background Art

[0002] As the world's fastest-growing green energy technology, wind power technology plays an important role in solving the energy crisis, and offshore wind power has become the focus of the future wind power market with its stronger and more stable wind resources and large single-unit capacity. In 2020, the global offshore wind power installed capacity increased by 6.1GW, and the cumulative installed capacity was 35GW. According to the Global Wind Energy Council, the global offshore wind power installed capacity will exceed 235GW in the next ten years. The leading edge of the offshore wind turbine blade is subjected to the impact of rain for a long time during the rotation process, which makes the leading edge very easy to erode. The leading edge of the blade tip has the highest speed and is relatively thin, so it becomes the most corroded area. The rough surface formed by rain erosion increases the aerodynamic drag coefficient of the blade. The reduction in blade power caused by erosion will cause the wind turbine to lose a huge amount of power generation every year. The leading edge protective film of the blade is generally composed of a puncture-proof and wear-resistant transparent polyurethane elastomer with good resilience. At present, many blade manufacturers use the leading edge film to protect the leading edge of the blade from corrosion.

[0003] The research on the rain erosion protection of the leading edge of large wind turbine blades currently mainly adopts the method of combining numerical simulation and experiment, but the existing rain erosion experimental device has a single working performance and cannot simulate a variety of rainfall environments. The traditional numerical simulation method has the problems of complex calculation, failure to consider the buffering effect of the blade composite matrix on the protective coating under the impact, the impact parameters are inconsistent with the actual working conditions, and failure to consider the inhibitory effect of surface water on the impact. Summary of the invention

[0004] In view of the problems existing in traditional numerical simulation methods, the main purpose of the present invention is to provide a simulation analysis method for the rain erosion performance of the leading edge protective film of wind turbine blades, so as to provide a theoretical basis for the research on rain erosion inhibition of wind turbine blades and the optimal design of blade leading edge protective materials.

[0005] The technical solution provided by the present invention includes: establishing a three-dimensional model of a wind turbine, simulating wind-driven rain on the wind turbine and obtaining the speed information of raindrops falling on the blades; calculating the raindrop impact velocity and the diameter distribution of raindrops under different rain intensities; establishing a blade composite material model and using the smooth particle fluid dynamics method to simulate raindrops; establishing actual impact conditions including raindrop diameter, impact velocity and impact angle, and obtaining the impact response of the blade coating under actual rainfall conditions through simulation. The specific steps involved in the solution are as follows:

[0006] Step 1: Establish the impeller wind field calculation model and divide the grid.

[0007] Step 2: Define the relevant parameters of the impeller wind field simulation.

[0008] Step 3: Release the discrete phase raindrops after the calculated wind field reaches convergence, and count the information of raindrops hitting the blade surface.

[0009] Step 4: Based on the tip speed, the vertical falling speed of the raindrop and the horizontal speed of the raindrop obtained in step 2, deduce the impact speed between the raindrop and the blade.

[0010] Step 5: Analyze the distribution of raindrop diameters under different rainfall intensities to obtain the range of raindrop diameters with a larger number in the rainfall.

[0011] Step 6: Establish a local model of the blade composite material and define material properties and interlayer contact.

[0012] Step 7: Establish a raindrop model and define its physical properties, and set the coupling contact between the raindrop and the local leaf model.

[0013] Step 8: Using raindrop diameter, impact angle and blade tip speed as variables, simulate raindrop impact on blades and analyze the impact of different working conditions on the rain erosion performance of the blade leading edge protective film.

[0014] Step 9: Use the SPH method to cover a layer of water film on the surface of the polyurethane protective film, simulate the impact of raindrops on the water-covered protective film, and analyze the weakening effect of surface water on the impact of raindrops.

[0015] Preferably, when establishing the wind wheel flow field analysis model in step 1, the minimum distance required for raindrops to reach a uniform descent should be considered, and the vertical height between the impeller apex and the upper wall of the fluid domain should be greater than this distance.

[0016] Preferably, the inlet wind speed distribution along the height in step 2 conforms to the power exponential wind profile law, and the wind speed model is defined by programming through a user-defined function module, and the wind speed distribution law is as follows:

[0017]

[0018] Where: V vs is the wind speed at different heights, in m / s; V hub is the wind speed at the hub height, in m / s; H is the height from the ground, in m; H hub is the hub height, in m; α is the wind shear exponent, set to 0.18.

[0019] Preferably, in step 3, the wind field is first calculated to reach convergence, and then a discrete phase model of simulated raindrops is released on the wall surface of the flow field. The raindrop release speed is 0, and the number of released raindrops is determined by the MP raindrop spectrum, and the formula is as follows:

[0020] n(d)=N0 exp(-Δ·d)

[0021] Where: n(d) is the number of raindrops of each diameter; N0 is the concentration parameter, which is 8000 / m -3 / mm -1 ; Δ=4.1I -0.21 , represents the slope factor, where I is the rainfall intensity, in mm / h; d is the raindrop diameter, in mm.

[0022] Preferably, the vertical falling speed of the raindrops in step 4 is determined by the following formula:

[0023] v(d)=9.154d 0.5 -2.6549+2.5342e -3.727 d 0.5 -0.389d 2.18

[0024] Where: v(d) is the velocity of raindrops of different diameters; d is the diameter of raindrops.

[0025] Preferably, in step 5, the raindrop diameter range with a large number under the rainfall intensities of 10, 30, 50 and 100 mm / hr is obtained according to the probability density function of the raindrop distribution, and the probability density function is as follows:

[0026]

[0027] Where: d is the raindrop size, unit is mm; I is the rainfall intensity, unit is mmh -1 .

[0028] Preferably, the blade model in step six is ​​composed of a polyurethane protective film, a gel coating, a chopped strand felt and a glass fiber reinforced plastic with laying angles of [+45° / -45°], the protective film thickness is 0.4 mm, and the thickness of the remaining layers of material is 0.6 mm, and the contact between the layers of material is defined by an automatic fixed contact algorithm between surfaces.

[0029] Preferably, the coupled impact between the raindrops and the blade model in step seven is achieved by a particle-surface smooth contact algorithm.

[0030] Preferably, in step eight, the raindrop diameter range is obtained by the raindrop diameter distribution probability density function, the impact angle range is 0-90°, and the tip speed range is 35-85m / s; in step nine, the water film thickness is 50μm, the physical property definition of the water film is the same as that of the raindrop, and the buffering effect of the water film on the impact of raindrops is analyzed by extracting the protective film energy data.

[0031] The beneficial effects produced by adopting the above technical scheme are as follows: the modeling method of raindrop impacting blade coating and the actual rainfall condition simulation method proposed in the present invention have improved the rain erosion simulation analysis, increased the horizontal velocity parameters of raindrops impacting blades at different heights, considered the buffering effect of blade composite materials and water covering the blade surface on raindrop impact, improved the simulation accuracy of blade rain erosion analysis, and enabled the simulation results to truly reflect the raindrop impact process and the impact response of the blade surface coating, providing a set of reliable technical solutions for the study of blade rain erosion impact. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A flow chart of the method of the present invention;

[0033] Figure 2 The three-dimensional model of the impeller in the embodiment of the present invention;

[0034] Figure 3 is a probability density function curve of raindrop size in an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of a blade composite material model in an embodiment of the present invention;

[0036] Figure 5 The tensile and compressive stress-strain curves of the blade gel coating in the embodiment of the present invention;

[0037] Figure 6 Graphs showing raindrop deformation at different times in an embodiment of the present invention;

[0038] Figure 7 This is a statistical diagram of the maximum impact stress values ​​of different raindrop diameters in an embodiment of the present invention;

[0039] Figure 8 It is a statistical diagram of the maximum impact stress at different angles in the embodiment of the present invention;

[0040] Fig. 9 This is a statistical diagram of the maximum impact stress values ​​at different blade tip speeds in an embodiment of the present invention;

[0041] Fig.10 It is a graph of energy-time curves of water impact and normal impact of the protective film in the embodiment of the present invention;

[0042] Fig.11 It is a peak-time curve diagram of water impact and normal impact stress of the protective film in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0044] like Figure 1 As shown, a method for simulating and analyzing the rain erosion performance of a wind turbine blade leading edge protective film comprises the following steps:

[0045] Step 1: Establish the impeller wind field calculation model and divide the grid.

[0046] First, the airfoil space coordinates obtained after coordinate transformation are imported into SolidWorks to establish the airfoil section. The hollow blade model is established using the surface lofting command. The blade and hub are assembled to obtain the impeller three-dimensional model as shown in the figure. Figure 2 shown.

[0047] Then, the three-dimensional model of the impeller is imported into ICEM CFD to create the fluid domain and the structural domain. Since raindrops of different diameters need a landing height of at least 20m to reach a uniform descent, the vertical distance between the upper wall of the fluid domain where the discrete phase raindrops are released and the highest point of the wind wheel needs to be considered when creating the fluid domain. Then, the fluid domain and the structural domain are structured for meshing. In order to improve the calculation accuracy, the mesh around the impeller needs to be encrypted.

[0048] Step 2: Define the relevant parameters of the impeller wind field simulation.

[0049] First, the grid file obtained in step 1 is imported into the Fluent solver to define materials, turbulence models, boundary conditions, etc. A segregated solver is used to implicitly solve the steady-state flow. The air in the flow field is simulated by an ideal gas model, the renormalization group RNG k-ω turbulence model is selected, and the effect of gravity acceleration is considered. The calculation residual of the control equation is set to 0.0001.

[0050] Then, the wind speed distribution along the height at the flow field inlet conforms to the power exponential wind profile law, and the wind speed input is realized through user-defined function module programming. The wind speed function is defined by the following formula:

[0051]

[0052] Where: V vs is the wind speed at different heights, in m / s; V hub is the wind speed at the hub height, in m / s; H is the height from the ground, in m; H hub is the hub height, in m; α is the wind shear index, which is taken as 0.18 in the present invention.

[0053] Step 3: Release the discrete phase raindrops after the calculated wind field reaches convergence, and count the information of raindrops hitting the blade surface.

[0054] Firstly, the pressure-velocity coupling in the flow equation is set to SIMPLE algorithm, the discretization format is set to the second-order upwind format, and finally the wind field is initialized for solution.

[0055] Then, the surface boundary of the wind turbine is set to capture, and the wall boundary of the computational domain is set to escape. In order to meet the minimum drop height requirement, the upper wall of the computational domain is used as the raindrop release surface to ensure that the vertical falling speed of the raindrop is uniform when it approaches the impeller height. The horizontal release speed of the raindrop is zero. Driven by the wind force of the stable flow field, the raindrop gradually approaches the horizontal wind speed at the location. The discrete phase model is used to simulate the raindrops, and the number of released raindrops is determined by the MP raindrop spectrum, and the formula is:

[0056] n(d)=N0exp(-Δ·d)

[0057] Where: n(d) is the number of raindrops of each diameter; N0 is the concentration parameter, which is 8000 / m -3 / mm -1 ; Δ=4.1I -0.21 , represents the slope factor, where I is the rainfall intensity, in mm / h; d is the raindrop diameter, in mm.

[0058] Finally, after the wind-driven rain simulation is completed, the raindrop information captured on the surface of each blade element segment is derived based on the blade element segment in the three-dimensional blade model, and the derived raindrop information is integrated and statistically analyzed to obtain the mean horizontal velocity of the raindrops impacting the blade.

[0059] Step 4: Based on the tip speed, the vertical falling speed of the raindrop and the horizontal speed of the raindrop, the impact speed between the raindrop and the blade is derived. The vertical falling speed of the raindrop is obtained by the following formula:

[0060] v(d)=9.154d 0.5 -2.6549+2.5342e -3.727 d 0.5 -0.389d 2.18

[0061] Where: n(d) is the number of raindrops of each diameter; N0 is the concentration parameter.

[0062] Among them, the horizontal velocity of the raindrop is obtained through step three, and the vertical and horizontal component expressions of the raindrop impact velocity are derived by combining the tip velocity and the vertical falling velocity:

[0063]

[0064]

[0065] Where: V dv 、V dp and V b are the vertical falling speed of raindrops, the horizontal speed of raindrops and the tip speed of wind turbine blades, in m / s; θ is the impact angle of raindrops.

[0066] Step 5. In natural rainfall, the diameter of raindrops is generally kept in the range of 0.1-6 mm. In order to analyze the distribution of raindrop diameters under different rainfall intensities, the cumulative distribution function of raindrops is derived to obtain the probability density function expression of raindrop distribution:

[0067]

[0068] Where: d is the raindrop size, unit is mm; I is the rainfall intensity, unit is mmh -1 .

[0069] According to the above formula, the probability density curves of raindrop distribution under rainfall intensities of 10, 30, 50 and 100 mm / hr are as follows: Figure 3 As shown, it was found that the number of raindrops with a diameter of 1-3 mm was the largest under each rainfall intensity.

[0070] Step 6: Establish a local model of the blade composite material and define material properties and interlayer contact.

[0071] The local model of blade composite material is established by stacking method, such as Figure 4 As shown, the blade model is divided into 5 layers, including the leading edge protection film, gel coating, chopped strand mat, and glass fiber reinforced plastic with laying angles of [+45° / -45°] from top to bottom. The size of each layer is 8×8mm, the thickness of the leading edge protection film is 0.4mm, and the thickness of the other layers of materials is 0.6mm.

[0072] This method uses thermoplastic polyurethane as the material of the leading edge protection film, uses the elastic-plastic material model (*MAT_24) to define its material properties, and defines the density as 1175 kg / m 3 , Young's modulus is 85.8MPa, Poisson's ratio is 0.49, and yield stress is 23.7MPa.

[0073] Thermosetting epoxy resin EponE826 is used as the gel coating material. The isotropic elastic-plastic material model (*MAT_124) is used to define the material properties of the gel coating. The material density is 1150 kg / m 3 , Young's modulus 2.5GPa, Poisson's ratio 0.4, and enter the tensile and compressive true stress-strain curves of EponE826 in the material card. The stress-strain curves are as follows: Figure 5 shown.

[0074] The chopped strand mat (CSM) at the bottom of the gel coat is a non-woven reinforcement material made of randomly oriented glass fibers. The chopped strand mat is assumed to be isotropic and its material properties are defined using the kinematic hardening elastoplastic material model (*MAT_3). The density is defined as 1452.8 kg / m 3 , Young's modulus 8GPa, Poisson's ratio 0.3, and yield stress 190MPa.

[0075] The glass fiber reinforced plastic is made of HiPer-Tex E-Glass fiber and Momentive epoxy resin. The composite biaxial layer glass fiber reinforced plastic is modeled as two separate layers in the [+45° / -45°] direction, and its material properties are defined using the composite failure model (*MAT_59). The relevant material parameters are shown in Table 1:

[0076] Table 1 Glass fiber reinforced plastic material properties

[0077] ρ <![CDATA[E 11 ]]> <![CDATA[E 22 =And 33 ]]> <![CDATA[v 12 =in 13 ]]> <![CDATA[v 23 ]]> NFLS SFLS <![CDATA[1864kg / m 3 ]]> 44.87GPa 12.13GPa 0.3 0.5 45.95GPa 49.51GPa <![CDATA[X C ]]> <![CDATA[Y C =Z C ]]> <![CDATA[X T ]]> <![CDATA[Y T =Z T ]]> <![CDATA[S 12 =S 13 =S 23 ]]> <![CDATA[G 12 =G 13 =G 23 ]]> 487MPa 131.9MPa 1006.3MPa 45.95MPa 49.51MPa 3.38GPa

[0078] The contact between the layers of the blade is defined using the surface-to-surface automatic fixed contact algorithm. In the contact tab, set OPTION to 6. The layers of material are bound to each other at the beginning to prevent any sliding. Delamination begins when the failure criteria are met. The inter-layer failure is defined by the following formula:

[0079]

[0080] Where: n is the normal stress acting on the interface; σ s is the shear stress acting on the interface; NFLS is the interlaminar normal strength; SFLS is the interlaminar shear strength.

[0081] Step 7: Establish a raindrop model and define its physical properties, and set the coupling contact between the raindrop and the local leaf model.

[0082] The finite element mesh is replaced by SPH particles, and the SphGen command in the LS-PrePost pre-processing software is used to create a spherical raindrop model. The number of SPH particles is 65k; the number of initial adjacent particles is defined as 500, and the fluid particle approximation theory is selected.

[0083] The inaction material model (*MAT_9) and the GRUNEISEN state equation are used to define the physical parameters of raindrops. The relevant parameters are shown in Table 2. The particle-surface smooth contact algorithm is used to define the contact between the raindrop and the local blade model, where the raindrop is defined as a slave and the leading edge protective coating is defined as the master surface. The algorithm checks the vertical distance between the slave particle and the master surface in each time step of the impact simulation. If penetration occurs, a contact interface force is applied, which can be regarded as applying a spring force on the contact interface. The magnitude of the applied force is as follows:

[0084] F=k*l p

[0085] Where: l p is the penetration distance between the particle and the solid surface; k is the stiffness of the equivalent spring.

[0086] Table 2 Water droplet characteristics and state equation parameters

[0087] ρ <![CDATA[v s ]]> v α <![CDATA[S1]]> <![CDATA[S2]]> <![CDATA[S3]]> <![CDATA[1000kg / m 3 ]]> 0.001Pa.s 1480m / s 0 2.56 -1.986 0.226

[0088] Step 8: Using raindrop diameter, impact angle and blade tip speed as variables, simulate raindrop impact on blades and analyze the impact of different working conditions on the rain erosion performance of the blade leading edge protective film.

[0089] The bottom surface of the local blade model is completely fixed, the side of the leading edge protection film is set as a non-reflective boundary, and the raindrop impact velocity is given. LS-DYNA is used to simulate the raindrop impact. The raindrop impact process is as follows: Figure 6 The energy and stress data of the polyurethane protective film are extracted, and the impact of raindrops is analyzed based on the effective stress or strain data.

[0090] According to the probability density distribution of raindrop diameters under different rainfall intensities in step 5, it is found that the number of raindrops with a diameter of 1-3 mm accounts for the largest proportion, so raindrop models with diameters of 1, 1.5, 2, 2.5 and 3 mm are established respectively. According to step 3, the average horizontal velocity of raindrops of each diameter is obtained, and the blade tip speed of 85 m / s under rated working conditions is adopted. Combined with step 4, the impact velocity of raindrops of each diameter is obtained, and the impact angle is fixed at 90°. Figure 7 is the maximum effective stress of raindrops with different diameters. It can be seen that the growth rate of the impact stress accelerates as the raindrop diameter increases. This is because as the raindrop diameter increases, its mass index increases, and the impact speed also increases continuously;

[0091] The tip speed was fixed at 85 m / s and the raindrop diameter was 3 mm. In combination with step 4, the horizontal and vertical speeds of the raindrops were set respectively to simulate the effect of the impact angle (15°, 30°, 45°, 60°, 75° and 90°). Figure 8The maximum effective stress of raindrop impact at different angles. It can be seen that the stress level of vertical impact is smaller. This is because the elastic deformation of the protective film produced during the impact and the horizontal velocity component work together to increase the stress level.

[0092] The raindrop diameter and impact angle are fixed, and the tip speed is set to 85, 75, 65, 55, 45, and 35 m / s, respectively. The raindrop is assigned the corresponding impact speed according to step 4. Fig. 9 is the maximum effective stress of raindrop impact at different blade tip speeds. It can be seen that compared with the rated blade tip speed, when the blade tip speed drops to 35m / s, the maximum impact stress decreases by 58%. This shows that reducing the speed of the wind turbine under rainfall conditions can effectively suppress the impact of rain erosion on the blade leading edge protective film.

[0093] Step 10: Use the SPH method to cover a 50 μm thick water film on the upper surface of the polyurethane protective film. The physical properties of the water film are defined in the same way as raindrops. The raindrop impact on the water-covered protective film is simulated to extract the stress and energy data of the leading edge protective film. Fig.10 The energy-time curves of the surface water protective film and the normal protective film. It can be seen that the protective film absorbs most of the impact load of raindrops, and on this basis, the surface water film further reduces the impact energy of raindrops. Fig.11 By comparing the maximum effective stress-time curve, it can be seen that the water film reduces the impact stress of raindrops and suppresses the water hammer stress caused by raindrop impact.

[0094] In summary, the present invention provides a method for simulating and analyzing the rain erosion performance of a leading edge protective film on a wind turbine blade. The method first establishes an impeller wind field analysis model, combines the discrete phase method to perform wind-driven rain simulation on the impeller to obtain the horizontal velocity of raindrops, and then obtains the impact velocity between the raindrops and the blades; uses a lamination method to establish a local composite material model of the blade, and uses a smooth particle fluid dynamics method to simulate raindrops to achieve coupled impact of raindrops and the blade model; sets three variables, namely, raindrop diameter, impact angle and blade tip speed, to analyze the impact response of the leading edge protective film under different working conditions, and simulates the inhibitory effect of water covering the surface of the protective film on the impact of raindrops; the method not only takes into account the buffering effect of the blade composite matrix and the surface water covering on the impact of raindrops on the leading edge protective film, but also uses a fluid simulation method to obtain the actual velocity of raindrops when impacting the blade, which can effectively simulate the rain erosion impact of the leading edge protective film under various working conditions.

[0095] The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for simulating and analyzing the rain erosion performance of a wind turbine blade leading edge protective film, characterized in that: The method comprises the following steps: Step 1: Establish the impeller wind field calculation model and divide the grid; Step 2: define the relevant parameters of the impeller wind field simulation; Step 3: After the wind field reaches convergence, the discrete phase raindrops are released and the information of raindrops hitting the blade surface is counted; Step 4: Based on the tip speed, the vertical falling speed of the raindrop and the horizontal speed of the raindrop obtained in step 3, deduce the impact speed between the raindrop and the blade: Step 5: Analyze the distribution of raindrop diameters under different rainfall intensities to obtain the range of raindrop diameters with a large number in the rainfall; Step 6: Establish a local model of the blade composite material and define material properties and interlayer contact; Step 7: Establish a raindrop model and define its physical properties, and set the coupling contact between the raindrop and the local leaf model; Step 8: Using raindrop diameter, impact angle and blade tip speed as variables, simulate raindrop impact on blades, and analyze the effects of different working conditions on the rain erosion performance of the blade leading edge protective film; Step 9: Use the SPH method to cover a layer of water film on the surface of the polyurethane protective film, simulate the impact of raindrops on the water-covered protective film, and analyze the weakening effect of the surface water on the raindrop impact; Step 1 is as follows: first, a hollow blade model is established according to the airfoil space coordinates, then the blade and the hub are assembled, and finally the fluid domain and the structure domain are created and the structured grid is divided. When creating the fluid domain, the minimum distance required for raindrops to fall at a uniform speed should be considered, and the vertical height between the impeller vertex and the upper wall of the fluid domain should be greater than this distance; In step 2, the inlet wind speed distribution along the height conforms to the power exponential wind profile law, and the wind speed model is defined by programming through the user-defined function module. The wind speed distribution law is as follows: Where: V vs is the wind speed at different heights, in m / s; V hub is the wind speed at the hub height, in m / s; H is the height from the ground, in m; H hub is the hub height, in m; α is the wind shear exponent, set to 0.18; Step 3 is as follows: first, the wind field is calculated to reach convergence, and then the raindrop discrete phase model is released on the wall surface of the flow field. The raindrop release speed is 0, and the number of released raindrops is determined by the MP raindrop spectrum. The formula is as follows: n(d)=N0exp(-Δ·d) Where: n(d) is the number of raindrops of each diameter; N0 is the concentration parameter, which is 8000 / m -3 / mm -1 ; Δ=4.1I -0.21 , represents the slope factor, where I is the rainfall intensity, in mm / h; d is the raindrop diameter, in mm; The vertical falling speed of the raindrops in step 4 is determined by the following formula: v(d)=9.154d 0.5 -2.6549+2.5342e -3.727 d 0.5 -0.389d 2.18 Where: v(d) is the velocity of raindrops of different diameters; d is the diameter of raindrops; In step 5, the probability density function of raindrop distribution is used to obtain the range of raindrop diameters with a large number under rainfall intensities of 10, 30, 50, and 100 mm / hr. The probability density function is as follows: Where: d is the raindrop size, unit is mm; I is the rainfall intensity, unit is mm / h.

2. The method for simulating and analyzing the rain erosion performance of a wind turbine blade leading edge protective film according to claim 1, characterized in that: In step six, the blade model consists of a polyurethane protective film, a gel coating, chopped strand mat, and glass fiber reinforced plastic with laying angles of +45° / -45°. The thickness of the protective film is 0.4 mm, and the thickness of the remaining layers of material is 0.6 mm. The automatic fixed contact algorithm between surfaces is used to define the connection between the layers of material.

3. The method for simulating and analyzing the rain erosion performance of a wind turbine blade leading edge protective film according to claim 1, characterized in that: In step seven, the coupled impact between the SPH raindrops and the leaf model is realized by the particle-surface smooth contact algorithm.

4. The method for simulating and analyzing the rain erosion performance of a wind turbine blade leading edge protective film according to claim 1, characterized in that: In step eight, the raindrop diameter range is obtained by the probability density function of the raindrop diameter distribution, the impact angle range is 0-90°, and the tip speed range is 35-85m / s; in step nine, the water film thickness is 50μm, the physical property definition of the water film is the same as that of the raindrop, and the buffering effect of the water film on the raindrop impact is analyzed by extracting the protective film energy data.

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