Accelerated simulation evaluation method for service life of wind power blade coating

Abstract

The invention provides an accelerated simulation evaluation method for the service life of a wind power blade coating, and the method comprises the steps: calculating effective impact kinetic energy when a to-be-tested blade coating fails through laboratory accelerated rain erosion test parameters and rain erosion test time based on an effective impact kinetic energy equivalence principle; and establishing a relation between a laboratory result and an actual service life for evaluating the service life of the wind power blade coating. The accelerated simulation evaluation method for the service life of the wind power blade coating is accurate in evaluation result, can directly draw a conclusion according to meteorological data published by the country, is convenient and rapid, and is suitable for multiple wind fields.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of detection, and in particular, relates to a wind power blade coating service life accelerated simulation evaluation method. BACKGROUND

[0002] As an important part of clean energy, the operation cost of wind power directly affects the economic benefits of the project. The main function of the wind power blade coating is to protect the blade body made of composite materials from the erosion of the external environment. Once the coating fails, water, ultraviolet light, etc. will directly attack the blade substrate, causing its structural strength to decrease, its weight to increase (moisture absorption), internal metal parts to corrode, and ultimately causing catastrophic damage. Therefore, the service life of the wind power blade coating is one of the key factors that determine the cost of the blade.

[0003] During the service process of the wind power blade, it is exposed to complex outdoor environments for a long time and needs to withstand multiple effects such as rainfall erosion, ultraviolet radiation, and temperature changes. Rain erosion damage is one of the main reasons for the failure of the leading edge coating of the blade. The impact kinetic energy generated by the collision between the high-speed rotating blade and the raindrops will gradually cause the coating to wear, crack, and even be penetrated, and finally lose the protection ability. The patent with the application number CN202410401071.6 discloses a wind power blade leading edge coating life prediction method based on rain erosion fatigue damage. By statistically analyzing the time distribution data of different rainfall intensities in the wind power field, the coating service life is predicted by combining the linear fatigue cumulative damage criterion. The patent with the application number CN202410401071.6 constructs a random rain field model, calculates the coating fatigue life by the Monte Carlo method based on the crack propagation theory and considering random factors such as raindrop shape and impact angle. Although these methods explore the correlation between rain erosion damage and coating life from different angles, they all have common defects: lack of core measurement indicators that can quantify the equivalence of laboratory accelerated testing and actual service conditions in the field, and cannot establish a clear conversion relationship between “laboratory accelerated testing time” and “actual service life of the blade coating”, which makes it difficult to directly guide the selection of the coating type, life prediction, and maintenance planning in the field.

[0004] Therefore, there is an urgent need for an evaluation method that can establish a connection between the laboratory test results of the rain erosion resistance test of the wind power blade coating and the actual service life, so as to directly calculate the actual service life of the coating from the laboratory rain erosion test results. SUMMARY

[0005] The problem solved by the present application is that the existing wind turbine blade coating service life accelerated simulation evaluation method does not establish a connection between laboratory test results and actual service life, and is not suitable for multiple wind farms. The present application is based on the effective impact kinetic energy equivalence principle, calculates the effective impact kinetic energy of the coating to failure through laboratory rain erosion test parameters and rain erosion test time, establishes a connection between laboratory results and actual service life, and is used to evaluate the service life of wind turbine blade coatings, and is suitable for multiple wind farms.

[0006] To achieve the above purpose, the present application provides a wind turbine blade coating service life accelerated simulation evaluation method, comprising the following steps:

[0007] S1, collecting rainfall data of at least one complete year in the target wind farm, the rainfall data is divided into multiple rainfall gradients according to rainfall intensity, and calculating the annual cumulative rainfall time T corresponding to the multiple rainfall gradients i and the average rainfall intensity I i ; based on the impact resistance of the blade coating to be tested in the target wind farm, set the damage threshold of the impact kinetic energy of a single raindrop, and consider a single raindrop with impact kinetic energy reaching or exceeding the damage threshold as an effective raindrop; according to the corresponding relationship between raindrop particle size distribution and rainfall intensity, obtain the total number of effective raindrops N in a year in the target wind farm 有效 , calculate the total effective impact kinetic energy E per unit area of the blade coating to be tested in the target wind farm environment in a year according to the following formula 1 eff :

[0008]

[0009] Wherein, Ekwind field is the impact kinetic energy of a single raindrop in the target wind farm; C is the raindrop capture coefficient, which is obtained according to the test calibration; ρ is the rainwater density, the unit is kg / m 3 ; A is the effective area of the blade to capture raindrops, the unit is m²; vr is the raindrop impact velocity, the unit is m / s; r is the blade rotation radius, the unit is m; t is the time for the blade to rotate one revolution, the unit is s;

[0010] S2, laboratory accelerated rain erosion test is carried out on the blade coating to be tested, and the simulated rainfall intensity, raindrop diameter and blade running speed are set; according to the set parameters, the accelerated rain erosion test is carried out until the blade coating to be tested reaches the predetermined failure standard, and the cumulative test time H is recorded; calculate the effective impact kinetic energy E of the blade coating to be tested per unit time per unit area in the accelerated rain erosion test in the laboratory according to the following formula 2 lab :

[0011]

[0012] Wherein, E kE is the impact kinetic energy of a single raindrop in the laboratory; a is the collision efficiency factor, which is obtained by calibration test; p is the rain density, with the unit of kg / m 3 ; d is the diameter of a single raindrop, with the unit of mm; S is the impact area of the coating of the blade to be tested, with the unit of m 2 ; T is the unit accelerated test time, with the unit of h; v tip is the tip speed of the blade to be tested, with the unit of m / s; N is the total number of raindrops per unit area per unit time in the accelerated rain erosion test; I is the average rainfall intensity, with the unit of mm / h;

[0013] S3, based on the effective impact kinetic energy equivalence principle, the predicted service life L of the coating of the blade to be tested in the target wind field is calculated according to the following formula 3:

[0014]

[0015] Wherein, the effective impact kinetic energy equivalence principle is that when the effective impact kinetic energy of raindrops borne by the coating of the blade to be tested in the laboratory accelerated rain erosion test is the same as the effective impact kinetic energy borne by it in the target wind field within a specified time, the rain erosion damage caused by the two is considered to be consistent.

[0016] Based on the effective impact kinetic energy equivalence principle, the laboratory rain erosion test parameters and rain erosion test time are used to calculate the effective impact kinetic energy of the coating to failure, which is associated with the effective impact kinetic energy in the actual wind field environment, and the laboratory-wind field life conversion formula is first proposed; the effective impact kinetic energy threshold is introduced in the actual wind field environment, the total effective impact kinetic energy per unit area of the wind field in a year is calculated according to the impact kinetic energy of a single raindrop on the surface of the sample, the interference of low-intensity invalid rainfall is excluded, and the accuracy of the equivalence relationship is improved by calibrating a and C.

[0017] In the present application, in order to facilitate calculation, p is preferably 1000 kg / m 3 .

[0018] Further, the calculation formula of E k风场 in step S1 is:

[0019]

[0020] The calculation formula of E k实验室 in step S2 is:

[0021]

[0022] Wherein, m r is the mass of a single raindrop, with the unit of kg.

[0023] The present application approximates the raindrop as a sphere, simplifying the calculation process.

[0024] Further, before the laboratory accelerated rain erosion test of the blade coating to be tested in step S2, the blade coating to be tested is further subjected to ultraviolet aging treatment.

[0025] In the present application, the ultraviolet aging time and intensity are set according to the target wind field environment; the ultraviolet aging time is preferably 2000-4000h, and more preferably 3000h; the light source used in the ultraviolet aging is preferably a UVA-340 light source, and the irradiation intensity is 0.83W / m 2 or a UVA-313 light source, and the irradiation intensity is 0.71W / m 2 .

[0026] Further, the blade coating to be tested is a front edge part of a wind turbine blade.

[0027] In the present application, the front edge part of the wind turbine blade is preferably an extension section extending from the blade tip to the blade root, and the length ratio of the extension section to the full length of the blade is 30%.

[0028] Further, the rainfall gradient in S1 is divided into: trace rainfall <0.0042mm / h, light rainfall 0.0042-0.41mm / h, moderate rainfall 0.42-1.04mm / h, heavy rainfall 1.04-2.08mm / h, storm 2.08-4.12mm / h, heavy storm 4.12-10.41mm / h, and extremely heavy storm ≥10.42mm / h; under the condition of rainfall gradient ≥0.42mm / h, the impact kinetic energy of a single raindrop is ≥damage threshold.

[0029] In the present application, the single raindrop damage threshold of the blade coating to be tested is determined by a single-drop impact tester or a rotating arm rain erosion tester in step S1; according to the raindrop impact velocity in the target wind field, the minimum raindrop diameter that produces no less than the single raindrop damage threshold is calculated; according to a raindrop particle size distribution model, the rainfall intensity corresponding to the minimum raindrop diameter is determined, and N effective is calculated according to the rainfall intensity.

[0030] Table 1 below is the impact kinetic energy of a single raindrop when the blade tip linear velocity is 100m / s.

[0031] Table 1 Terminal velocity, mass, relative impact velocity and impact kinetic energy of a raindrop when the blade tip linear velocity is 100m / s

[0032] Raindrop diameter (mm) Terminal velocity (m / s) Raindrop mass (kg) Relative impact velocity (m / s) Impact kinetic energy (mJ) 0.75 3.50 2.27 x 10 -7 ]] 103.50 1.18 1.00 4.03 5.24 x 10 -7 ]]> 104.03 2.83 1.25 4.84 1.02 x 10 -6 ]]> 104.84 5.61 1.50 5.56 1.77 x 10 -6 ]]> 105.56 9.86 1.75 6.20 2.80 x 10 -6 ]]> 106.20 15.78 2.00 6.76 4.19 x 10 -6 ]]> 106.76 23.87 2.25 7.27 5.97 x 10 -6 ]]> 107.27 34.35 2.75 8.13 1.09 x 10 -5 ]]> 108.13 63.63 3.00 8.49 1.41 x 10 -5 ]]> 108.49 82.95

[0033] When the rainfall intensity is ≥0.42mm / h, the diameter of the raindrop is usually above 1.00mm, at which time the impact kinetic energy is >2.83mJ, and 2.83mJ is set as the damage threshold of a single raindrop.

[0034] In most cases, the rainfall intensity is complex and changeable within a year, and not all the impact kinetic energy of the rainfall can cause damage to the coating, and the present application solves the problem of low-intensity invalid rainfall interference in complex wind field environment by setting a "damage threshold".

[0035] The present application divides the rainfall intensity based on the rainfall data provided by the National Meteorological Administration, which is convenient and accurate, avoids the calculation result deviation caused by the traditional self-defined rainfall gradient, and is convenient for predicting the service life of the blade coating in different regions, and improves the scientificity and universality of the scheme.

[0036] Further, the effective area A of the blade capturing raindrops in S3 is 0.1 m².

[0037] Further, in step S1, the calibration method of the raindrop capturing coefficient C is: under the set rainfall intensity, the number of raindrops actually impacting the coating of the blade to be tested within a unit time is counted, the total amount of raindrops is calculated theoretically, the actual impact probability of raindrops is calculated and corrected to obtain C and 0

[0038] In step S2, the calibration method of the collision efficiency factor a is: under the set rainfall and blade tip line speed test conditions, a rain erosion test is carried out, the number of raindrops actually impacting the coating of the blade to be tested within a unit time is counted, the total amount of raindrops is calculated theoretically, the actual impact probability of raindrops is calculated and corrected to obtain a and 0

[0039] The process of capturing raindrops by the blade in the wind field is affected by various complex factors (such as air flow disturbance, blade rotation posture, raindrop flight trajectory deviation), and it is not possible that all raindrops will impact the effective area of the blade, which does not conform to the actual situation. By calibrating C, the theoretical error of the complex environment of the wind field is offset, which is close to the actual service scene; at the same time, it can be adapted to different wind fields, for example, the air flow disturbance in the coastal wind field is large, the value of C may be low; the air flow in the inland wind field is stable, the value of C may be high;

[0040] In the laboratory, not all raindrops can 100% impact the sample surface (there are raindrop deviation, splashing, etc.), so an actual impact probability correction factor a needs to be calibrated by test.

[0041] Further, the failure standard in S3 is that the blade coating to be tested appears a breakdown phenomenon or a weight loss rate reaches 1%.

[0042] The breakdown phenomenon of the present application is that the coating surface appears a penetrating damage, and loses the protection ability to the blade substrate.

[0043] Further, in S3, the raindrop impact velocity v r is calculated when the raindrop falling terminal velocity is considered, and then v r = 4×d 0.56 , wherein d is the diameter of the raindrop.

[0044] The final raindrop impact velocity of the application is the vector superposition value of the raindrop falling terminal velocity and the blade tip line velocity, but since the blade tip line velocity is much greater than the terminal velocity of the raindrop falling, the terminal velocity of the raindrop falling is often ignored in the calculation.

[0045] Further, the accuracy of the simulation evaluation method is more than 80%.

[0046] Compared with the prior art, the application has the following advantages:

[0047] The application replaces the unmeasurable parameters with the directly measurable parameters (rainfall intensity, blade tip speed, etc.), combines the "effective impact kinetic energy equivalence" principle, establishes the quantitative correlation between the laboratory accelerated test and the actual service in the wind field, and the prediction accuracy is as high as 80.4%; different wind field environments can be adapted by inputting target wind field rainfall data, the data acquisition cost is low, reliable quantitative data support can be provided for wind turbine blade coating selection and maintenance cycle planning, and the full life cycle cost of the wind field is effectively reduced. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 It is a wind turbine blade coating service life accelerated simulation evaluation method of the application. DETAILED DESCRIPTION

[0049] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the specific embodiments of the application will be described in detail below with reference to the drawings.

[0050] The rainfall conditions of a certain wind field are shown in Table 2, and there is a wind turbine blade with a length of 110m in the wind field, and the time for one revolution is 10s, and the impact kinetic energy generated by a single raindrop with a rainfall intensity of ≥0.42mm / h is greater than the damage threshold of a single raindrop. The investigation area A is 0.1m 2 ; according to formula 1, the total effective impact kinetic energy E eff in one year is calculated, wherein the raindrop capture coefficient C obtained by calibration is 0.1. The calculation result is: 44.17kJ.

[0051] Table 2: Annual rainfall intensity gradient and cumulative time statistics of a certain wind field

[0052] No. Class Average rainfall intensity I, mm / h Rainfall time T, h 1 Trace and light rain ＜0.25 318 2 Moderate rain 0.73 235 3 Heavy rain 1.56 186 4 Storm 3.10 102 5 Heavy storm 7.26 68 6 Very heavy storm 17.50 33

[0053] The average rainfall intensity I is calculated by taking the maximum and minimum values of the intensity range.

[0054] A U-shaped sample coated with a wind turbine blade leading edge protective coating is placed in a light source with a UVA-340 intensity of 0.83W / m 2After the UV aging test for 3000h, the laboratory accelerated rain erosion test was carried out: the rainfall condition was set to 30mm / h, and the raindrop diameter was 2.4mm; the tip line speed was 160m / s. The effective impact kinetic energy E of the coating per hour was calculated according to formula 2 lab . The collision efficiency factor α obtained by calibration was 0.5, and the calculation result was 19.20kJ.

[0055] The coating after the aging test appeared breakdown failure after 13h. The simulation analysis calculation can obtain that the protection life of the leading edge protection coating under the condition is about 5.6 years.

[0056] According to the feedback of the wind field, the actual service life of the leading edge protection coating is 4.5 years, and the accuracy of the service life accelerated simulation evaluation method can reach 80.4%.

[0057] Although the present application is disclosed as above, the present application is not limited to this. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application, and therefore the protection scope of the present application should be subject to the range defined by the claims.

Claims

1. A method for accelerated simulation evaluation of the service life of wind turbine blade coatings, characterized in that, Includes the following steps: S1. Collect rainfall data for at least one full year for the target wind field. The rainfall data is divided into multiple rainfall gradients according to rainfall intensity. Calculate the annual cumulative rainfall time T corresponding to the multiple rainfall gradients. i With average rainfall intensity I i Based on the impact resistance of the blade coating under test in the target wind field, a damage threshold for the impact kinetic energy of a single raindrop is set. A single raindrop with an impact kinetic energy reaching or exceeding the damage threshold is considered a valid raindrop. According to the correspondence between raindrop size distribution and rainfall intensity, the total number of valid raindrops N in the target wind field over one year is obtained. 有效 The total effective impact kinetic energy E borne per unit area of ​​the blade coating under test in the target wind field environment over one year is calculated according to the following formula 1. eff : Among them, E k风场 C represents the impact kinetic energy of a single raindrop within the target wind field; C is the raindrop trapping coefficient, obtained through experimental calibration; ρ is the rainwater density, in kg / m³. 3 A represents the effective area of ​​the blade that captures raindrops, measured in m²; v r t is the raindrop impact velocity, in m / s; r is the blade rotation radius, in m; t is the time it takes for the blade to complete one rotation, in s. S2. Conduct a laboratory accelerated rain erosion test on the coating of the blade under test, setting the simulated rainfall intensity, raindrop diameter, and blade running speed; conduct the accelerated rain erosion test according to the set parameters until the coating of the blade under test reaches the predetermined failure standard, and record the cumulative test time H; calculate the effective impact kinetic energy E per unit time per unit area of ​​the coating of the blade under test in the laboratory accelerated rain erosion test according to the following formula 2. lab : Among them, E k实验室 α represents the impact kinetic energy of a single raindrop in the laboratory; α is the collision efficiency factor, obtained through experimental calibration; ρ is the rainwater density, in kg / m³. 3 d represents the diameter of a single raindrop in mm; S represents the area of ​​the impact zone of the coating on the blade under test in m². 2 T represents the unit acceleration test time, in hours (h); v tip N represents the tip linear velocity of the blade under test, in m / s; N represents the total number of raindrops per unit area per unit time in the accelerated rain erosion test; and I represents the average rainfall intensity, in mm / h. S3. Based on the effective impact kinetic energy equivalence principle, calculate the predicted service life L of the coating on the blade under test in the target wind field according to the following formula 3: The effective impact kinetic energy equivalence principle states that when the effective impact kinetic energy of raindrops on the coating of the blade under test in the laboratory accelerated rain erosion test is the same as the effective impact kinetic energy it receives within a specified time in the target wind field, the degree of rain erosion damage caused by the two can be considered to be the same.

2. The method for accelerated simulation evaluation of wind turbine blade coating service life according to claim 1, characterized in that, In step S1, E k风场 The calculation formula is: In step S2, E k实验室 The calculation formula is: Where, m r The mass of a single raindrop is expressed in kg.

3. The method for accelerated simulation evaluation of wind turbine blade coating service life according to claim 2, characterized in that, Before conducting the accelerated rain erosion test in the laboratory, step S2 also includes subjecting the coating of the blade to be tested to ultraviolet aging treatment.

4. The method for accelerated simulation evaluation of wind turbine blade coating service life according to claim 2 or 3, characterized in that, The coating on the blade to be tested is located at the leading edge of the wind turbine blade.

5. The method for accelerated simulation evaluation of wind turbine blade coating service life according to claim 2 or 3, characterized in that, The rainfall gradient described in S1 is divided into: trace rainfall <0.0042 mm / h, light rainfall 0.0042~0.41 mm / h, moderate rainfall 0.42~1.04 mm / h, heavy rainfall 1.04~2.08 mm / h, rainstorm 2.08~4.12 mm / h, torrential rain 4.12~10.41 mm / h, and extremely heavy rain ≥10.42 mm / h; under the condition of rainfall gradient ≥0.42 mm / h, the impact kinetic energy of a single raindrop is ≥ the damage threshold.

6. The method for accelerated simulation evaluation of wind turbine blade coating service life according to claim 3, characterized in that, The effective area A for capturing raindrops by the blades described in S3 is 0.1 m².

7. The method for accelerated simulation evaluation of wind turbine blade coating service life according to claim 3, characterized in that, In step S1, the calibration method for the raindrop capture coefficient C is as follows: under the set rainfall intensity, the number of raindrops that actually hit the coating of the blade under test per unit time is counted, and the actual impact probability of the raindrops is calculated and corrected to obtain C, where 0 < C < 1. In step S2, the calibration method for the collision efficiency factor α is as follows: under the set rainfall and tip linear velocity test conditions, a rain erosion test is carried out, the number of raindrops that actually impact the coating of the blade under test per unit time is counted, and the actual impact probability of raindrops is calculated and corrected to obtain α, where 0 < α < 1.

8. The method for accelerated simulation evaluation of wind turbine blade coating service life according to claim 1, characterized in that, The failure criteria described in S2 are that the coating of the blade under test shows a breakdown phenomenon, or the weight loss rate reaches 1%.

9. The method for accelerated simulation evaluation of wind turbine blade coating service life according to claim 1, characterized in that, Calculate the raindrop impact velocity v in S3 r If the velocity of the raindrops falling to the terminal needs to be considered, then v r =4×d 0.56 , where d is the diameter of the raindrop.

10. The method for accelerated simulation evaluation of wind turbine blade coating service life according to claim 1, characterized in that, The accuracy of the simulation evaluation method is above 80%.

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