Reliability Prediction Method for Thermal Barrier Coatings under CMAS Deposition

Abstract

The present invention discloses a method for predicting the reliability of thermal barrier coatings under CMAS deposition, including establishing a grid model, establishing a thermo-mechanical coupling model for CMAS deposition of thermal barrier coatings, etc. Starting from the critical velocity deposition model, a particle deposition model is established to obtain the particle deposition rate at any position on the coating surface, and then the particle deposition thickness at any position on the coating surface can be quickly obtained. Combining with the temperature distribution of the turbine blade, the CMAS penetration depth can be further obtained, so as to calculate the energy release rate and damage value inside the coating. The method of the present invention overcomes many defects in the prior art, such as time-consuming and laborious experiments, large experimental measurement errors, and inability to replicate experimental conditions, and has certain guiding significance for the development, design, preparation and application of thermal barrier coatings in the CMAS service environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of engineering thermophysics, and particularly relates to a method for predicting the reliability of thermal barrier coatings under CMAS deposition. Background Art

[0002] Thermal barrier coatings (TBCs) refer to a thin layer of oxidation ceramic coating applied to high-temperature components at the hot end of aeroengines, which have properties such as high temperature resistance, low thermal conductivity, and corrosion resistance. They can improve the temperature environment, service life, thermal efficiency, and fuel cleanliness of the engine. However, due to the complex structure and harsh working environment of thermal barrier coatings, coating failure and peeling have become an important bottleneck restricting the safe application of thermal barrier coatings. At the same time, due to the influence of various factors such as volcanic eruptions, coal combustion, and sandstorms, the dust in the atmosphere is increasing day by day, and the harm of CMAS (metal oxides such as CaO-MgO-Al2O3-SiO2) deposits to the engine is becoming more and more serious. With the continuous increase in the thrust-to-weight ratio, the turbine inlet temperature has increased significantly, strengthening the damage of CMAS molten deposition to thermal barrier coatings. Therefore, aiming at the problem of thermal barrier coating failure caused by CMAS particle deposition, developing a prediction method for the influence of CMAS deposition on the reliability of thermal barrier coatings in a dusty environment will be an urgent problem to be solved.

[0003] At the present stage, scholars have explored various aspects for predicting the influence of CMAS deposition on the reliability of thermal barrier coatings. Chen used the finite element method to calculate the energy release rate and mode mixing of coating delamination. This method considered the columnar microstructure of EB-PVD TBCs, considered the influence of CMAS thickness, mechanical properties, and thermal properties, and compared the steady-state energy release rate with the theoretical model. Zhang et al. established a two-dimensional periodic model considering the microstructure of thermal barrier coatings prepared by electron beam physical vapor deposition (EB-PVD) and CMAS penetration. The research shows that during the rapid cooling process, the infiltrated CMAS will induce a high in-plane tensile stress field in the ceramic layer, accelerating the development of vertical cracks in the ceramic layer. Cai et al. established a numerical model considering CMAS penetration in the coating and studied the influence of CMAS penetration depth and microstructure shape on the stress distribution and stress level of the coating. During the thermal cycle, the stress continuously increases, eventually leading to premature peeling of TBCs.

[0004] At present, most of these studies are on the coating failure mechanism under CMAS deposition. However, due to the strong randomness of the particle size, movement trajectory, and deposition adhesion, and in addition, the randomness of the structure and environmental parameters, the influence of particle deposition on the coating reliability is uncertain. Therefore, it is necessary to develop a prediction method for the coating reliability under different deposition conditions.

[0005] Miller first carried out research on the prediction of coating life, established a model to simulate the life of thermal barrier coatings in high-temperature environments, combined the oxidation-induced strain with cyclic strain, and regarded failure as a function of the heating cycle duration. Wei Hongliang et al. conducted high-temperature oxidation experiments, thermal fatigue experiments and finite element simulation studies on circular tubes with thermal barrier coatings. Based on the research results, a life prediction model that can reflect the coupling effect of oxidation damage and thermal fatigue damage was established. Jonnalagadda et al. further developed the previously established life model based on fracture mechanics and verified it by comparing with experimental results. The life model is based on the propagation of microcracks and uses Paris' law to predict the coating failure period.

[0006] At present, the failure prediction models of thermal barrier coatings are generally divided into empirical models based on experimental conclusions and theoretical models based on physics / chemistry or their coupling. The traditional failure prediction models of thermal barrier coatings can generally only carry out failure prediction for a single failure mode under specific working conditions. However, in the actual service environment of turbine blades, the uncertainties of material parameters, geometric structures and loads will all affect the failure life of thermal barrier coatings. At the same time, the traditional prediction models can only give the average service life of thermal barrier coatings and cannot know the life distribution of thermal barrier coatings, which is not conducive to the safe application of thermal barrier coatings. Compared with life prediction, service reliability analysis starts from the perspective of probability and statistics, considers various failure forms of thermal barrier coatings, and establishes corresponding failure criteria, which not only provides a reference for the safe service of thermal barrier coatings, but also provides a basis for the optimized design of thermal barrier coatings. Therefore, it is necessary to develop a reliability prediction method for thermal barrier coatings in dusty environments. Based on this method, the reliability distribution of thermal barrier coatings on the surface of turbine blades under different particle sizes and service times can be predicted. Summary of the Invention

[0007] The purpose of the present invention is to realize the prediction of the service reliability of thermal barrier coatings on turbine blades under different dusty environments and service times, and provide a reliability prediction method for thermal barrier coatings under CMAS deposition;

[0008] In order to achieve the above purpose, the present invention adopts the following technical solutions: A reliability prediction method for thermal barrier coatings under CMAS deposition, including:

[0009] Step 1: Divide the tetrahedral mesh of the turbine blade component and the cascade channel model, and conduct mesh independence verification to establish the mesh models of the turbine blade component and the cascade channel. Then import the mesh models of the turbine blade component and the cascade channel into Fluent, and set the numerical calculation boundary conditions according to the typical operating conditions of aero-engines to obtain the temperature distribution of the turbine blade;

[0010] Step 2: Establish a particle deposition model, obtain the number of particles deposited on the surface of the thermal barrier coating through the particle deposition model, and then obtain the particle deposition thickness on the surface of the thermal barrier coating based on the number of particles deposited on the surface of the thermal barrier coating;

[0011] Step 3: Based on the temperature distribution of the turbine blade obtained in Step 1 and combined with the particle deposition thickness on the surface of the thermal barrier coating obtained in Step 2, obtain the CMAS penetration depth on the surface of the thermal barrier coating;

[0012] Step 4: Based on the particle deposition thickness of the thermal barrier coating obtained in Step 2 and the CMAS penetration depth on the surface of the thermal barrier coating obtained in Step 3, and combined with the energy release rate calculation formula, calculate the internal energy release rate on the surface of the thermal barrier coating. Then, the internal energy release rate on the surface of the thermal barrier coating is calculated through the internal damage calculation formula to obtain the internal damage value on the surface of the thermal barrier coating, that is, the internal damage value distribution of the thermal barrier coating;

[0013] Step 5: Predict the reliability of the thermal barrier coating through the internal damage value of the thermal barrier coating obtained in Step 4 and output the corresponding prediction results.

[0014] Further, the specific steps of Step 2 include:

[0015] Step 2.1: Establish a UDF for the deposition mechanism and calculate the critical velocity through the UDF of the deposition mechanism;

[0016] Step 2.2: Calculate the normal and tangential velocities of the particle after collision through the velocity formula before and after particle collision, and then calculate the angle of the particle after collision through the normal and tangential velocities of the particle after collision;

[0017] Step 2.3: Compare the critical velocity with the normal velocity of the particle after collision. If the normal velocity of the particle after collision is greater than the critical velocity, the particle will rebound and no deposition will occur, and go to Step 2.4. If the normal velocity of the particle after collision is greater than the critical velocity, the particle will adhere to the wall surface and deposition will occur;

[0018] Step 2.4: Repeat Step 2.2 to Step 2.3 until the particle no longer collides with the thermal barrier coating on the surface of the blade;

[0019] Step 2.5: After the above steps are completed, count the deposited particles to obtain the number of particle depositions, and then calculate the particle deposition thickness on the surface of the thermal barrier coating through the number of particle depositions.

[0020] Further, the UDF of the deposition mechanism is specifically:

[0021]

[0022]

[0023]

[0024] In the formula, V cr is the critical velocity, E is the Young's modulus of the composite material, and E s is the surface Young's modulus, and E p is the Young's modulus of the particles, and it satisfies E P = E0·e -aT , ν s is the surface Poisson's ratio, and ν p is the Poisson's ratio of the particles, D p is the radius of the particle, and ρ is the particle density.

[0025] Furthermore, the velocity formula of the particles before and after collision is specifically:

[0026]

[0027] In the formula, v 1n , v 2n and v 1t , v 2t are the normal and tangential velocities of the particles before and after collision respectively, and β1 is the angle between the velocity of the particles before collision and the wall tangent.

[0028] Furthermore, the specific calculation formula for the particle deposition thickness is:

[0029]

[0030] In the formula, h is the deposition thickness / m, m is the particle deposition mass of the current grid / kg, and s is the area of the current deposition grid / m 2 .

[0031] Furthermore, the specific calculation formula for the energy release rate is:

[0032]

[0033] In the formula, i = 1, 2, 3 respectively represent the CMAS layer, the CMAS penetration layer, and the TBC layer, h i represents the depth of each layer, E i represents the Young's modulus of each layer, σ i represents the in-plane residual stress generated by the thermal expansion mismatch in each layer, represents the residual stress of each layer at the coating peeling location.

[0034] Furthermore, the internal damage calculation formula is:

[0035]

[0036] Wherein, D is the internal damage value of the coating. The value range of D is 0 to 1. The larger the D value, the greater the coating damage. When the D value reaches 1, the coating is considered to fail. G ss is the energy release rate / J·m -2 , and a and b are fitting parameters.

[0037] Beneficial effects: The present invention can construct a thermo-mechanical coupling model for the failure of thermal barrier coatings under CMAS deposition according to the CMAS deposition thickness and penetration depth, and realize the prediction of the service reliability of thermal barrier coatings on turbine blades under different dust-containing environments and service times. It has the advantages of fast simulation speed, economy, time-saving and labor-saving, visualization, and simplification of complex problems. Moreover, it can process a large amount of information and can accurately predict the service reliability of the coating, overcoming many defects in the prior art such as time-consuming and laborious experiments, large experimental measurement errors, and inability to replicate experimental conditions. The research work has certain guiding significance for the development, design, preparation and application of thermal barrier coatings in the CMAS service environment. Description of the Drawings

[0038] Figure 1 is a schematic diagram of the physical model of the turbine blade and the setting of boundary conditions.

[0039] Figure 2 is a schematic diagram of particle rebound.

[0040] Figure 3 is a schematic diagram of CMAS deposition and each layer of the thermal barrier coating.

[0041] Figure 4 is a CMAS damage evolution diagram of the thermal barrier coating on the mid-section line of the turbine blade.

[0042] Figure 5 is a damage distribution diagram of the thermal barrier coating on the mid-section line of the turbine blade affected by particle size. Detailed Embodiments

[0043] The following further explains the present invention with reference to the drawings.

[0044] The present invention provides a method for predicting the reliability of thermal barrier coatings under CMAS deposition, including:

[0045] Step 1: Divide the tetrahedral mesh of the turbine blade component and the cascade channel model, and conduct mesh independence verification to establish the mesh models of the turbine blade component and the cascade channel. Then import the mesh models of the turbine blade component and the cascade channel into Fluent, and set the numerical calculation boundary conditions according to the typical operating conditions of aeroengines to obtain the temperature distribution of the turbine blade.

[0046] Step 2: Establish a particle deposition model, obtain the number of particles deposited on the surface of the thermal barrier coating through the particle deposition model, and then obtain the particle deposition thickness on the surface of the thermal barrier coating based on the number of particles deposited on the surface of the thermal barrier coating.

[0047] Step 3: Based on the temperature distribution of the turbine blade obtained in Step 1 and combined with the particle deposition thickness on the surface of the thermal barrier coating obtained in Step 2, obtain the CMAS penetration depth on the surface of the thermal barrier coating.

[0048] Step 4: Based on the particle deposition thickness of the thermal barrier coating obtained in Step 2 and the CMAS penetration depth on the surface of the thermal barrier coating obtained in Step 3, combined with the energy release rate calculation formula, calculate the internal energy release rate on the surface of the thermal barrier coating. Then, the internal energy release rate on the surface of the thermal barrier coating is calculated through the internal damage calculation formula to obtain the internal damage value on the surface of the thermal barrier coating, that is, the internal damage value distribution of the thermal barrier coating.

[0049] Step 5: Predict the reliability of the thermal barrier coating through the internal damage value of the thermal barrier coating obtained in Step 4 and output the corresponding prediction results.

[0050] In Step 1, based on a typical turbine blade, establish a physical model of the blade and the cascade passage. As Figure 1 shown, according to the actual situation in the computational domain, use Ansys mesh software to divide the tetrahedral unstructured mesh, and encrypt the mesh at the fluid-structure interface. The height of the first layer of mesh is set to 0.006 mm, the growth rate is 1.1, and a total of 20 layers are set to ensure that y + < 1 at the near-wall surface. At the same time, in order to reduce the computational amount and improve the computational efficiency, the mesh is appropriately thinned in the area far from the fluid-structure interface and at the inlet and outlet sections of the model. To eliminate the influence of mesh division on the calculation results, mesh independence verification is carried out before carrying out the numerical calculation work. Adjust the overall mesh size by changing the mesh growth rate in the boundary layer and the height of the first layer of mesh in the normal direction of the blade. Select the mesh number with high calculation accuracy and less computational resource consumption, establish the mesh model of the turbine blade component and the cascade passage, and then import the mesh model of the turbine blade component and the cascade passage into Fluent. According to the typical operating conditions of the aero-engine, set the numerical calculation boundary conditions to obtain the temperature distribution of the turbine blade.

[0051] In this embodiment, 5 million mesh numbers are selected.

[0052] In Step 2, the specific steps are as follows:

[0053] Step 2.1: Establish a UDF for the deposition mechanism and calculate the critical velocity through the UDF of the deposition mechanism.

[0054] Step 2.2: Calculate the normal and tangential velocities of the particle after collision through the velocity formula before and after particle collision, and then calculate the angle of the particle after collision through the normal and tangential velocities of the particle after collision.

[0055] Step 2.3: Compare the critical velocity with the normal velocity of the particle after collision. If the normal velocity of the particle after collision is greater than the critical velocity, the particle will rebound and no deposition will occur, and then go to Step 2.4. If the normal velocity of the particle after collision is greater than the critical velocity, the particle will adhere to the wall surface and deposition will occur.

[0056] Step 2.4: Repeat Step 2.2 to Step 2.3 until the particle no longer collides with the thermal barrier coating on the blade surface.

[0057] Step 2.5: After the above steps are completed, count the deposited particles to obtain the number of particle depositions, and then calculate the particle deposition thickness on the surface of the thermal barrier coating through the number of particle depositions.

[0058] In Step 2.1, the UDF of the deposition mechanism is specifically:

[0059]

[0060]

[0061]

[0062] In the formula, V cr is the critical velocity, E is the Young's modulus of the composite material, E s is the surface Young's modulus, E p is the Young's modulus of the particle, and it satisfies E P = E0·e -aT , ν s is the surface Poisson's ratio, ν p is the Poisson's ratio of the particle, D p is the particle radius.

[0063] In Step 2.2, calculate the normal and tangential velocities of the particle after collision through the velocity formula before and after particle collision, and then calculate the angle of the particle after collision through the normal and tangential velocities of the particle after collision. As Figure 2 shown, it is specifically:

[0064]

[0065] In the formula, v 1n and v 1t are respectively the normal and tangential velocities of the particle before collision, v 2n and v 2tThey are the normal and tangential velocities after particle collision respectively, and β1 is the angle between the velocity before particle collision and the wall tangent;

[0066] And according to v 2n and v 2t the angle formula after particle collision can be obtained as:

[0067]

[0068] The governing equation of particle motion is:

[0069]

[0070] In the formula, F(u - u p ) is the drag force acting on the particle per unit mass / N·kg -1 ; u and u p are the fluid velocity and particle velocity / m·s -1 , where F is the resultant force acting on the particle, and its definition is:

[0071]

[0072]

[0073]

[0074] In the formula, C D is the nonlinear drag coefficient; Re p is the particle Reynolds number; ρ and ρ p are the fluid density and particle density / kg·m -3 respectively; d p is the particle diameter / m; μ is the dynamic viscosity of the fluid / N·s·m -2 .

[0075] The governing equation of particle heat transfer is:

[0076]

[0077] In the formula, m p is the particle mass, C p,p is the specific heat of the particle, T p is the particle temperature, A p is the particle surface area, h c is the convective heat transfer coefficient.

[0078] In steps 2.3 to 2.5, when the CMAS particles move at high speed in the flow channel, they may collide with the blade surface multiple times, that is, bounce back after collision and then collide with other parts of the blade. Therefore, repeat steps 2.2 to 2.3 to ensure the accuracy of the particle deposition quantity. Among them, in the process of repeating step 2.2, the normal and tangential velocities of the particles before collision in the particle collision velocity formula are determined by the previous step 2.3.

[0079] And in step 2.5, the specific calculation formula for the particle deposition thickness is:

[0080]

[0081] In the formula, h is the deposition thickness / m, m is the particle deposition mass of the current grid / kg, and s is the area of the current deposition grid / m 2 .

[0082] In step 3, according to the turbine blade temperature distribution obtained in step 1 and combined with the particle deposition thickness on the surface of the thermal barrier coating obtained in step 2, the CMAS penetration depth on the surface of the thermal barrier coating can be analyzed and obtained in the Fluent software.

[0083] In step 4, the specific calculation formula for the energy release rate is:

[0084]

[0085] In the formula, i = 1, 2, 3 respectively represent the CMAS layer, the CMAS penetration layer and the TBC layer, h i represents the depth of each layer, E i represents the Young's modulus of each layer, σ i represents the in-plane residual stress generated by the thermal expansion mismatch in each layer, represents the residual stress in the coating.

[0086] And the internal damage calculation formula is:

[0087]

[0088] In the formula, D is the internal damage value of the coating. The value range of D is 0 to 1. The larger the D value, the greater the coating damage. When the D value reaches 1, the coating is considered to fail. G ss is the energy release rate / J·m -2 , a, b are fitting parameters.

[0089] In this embodiment, the magnitude of the in-plane residual stress generated by the thermal expansion mismatch in each layer (away from the free edge) is:

[0090] σ i = E i Δα i ΔT = Ei (α sub -α i )ΔT

[0091] Wherein, α i is the coefficient of thermal expansion of each layer, α sub is the coefficient of thermal expansion of the substrate, and ΔT is the difference between the working temperature and the ambient temperature of the coating.

[0092] Schematic diagrams of CMAS deposition and each layer of the thermal barrier coating are shown as Figure 3 shown, where the depth h i , Young's modulus E i and coefficient of thermal expansion α i can be expressed as:

[0093] h1 = h CMAS

[0094] h2 = h pen

[0095] h3 = h TBC -h pen

[0096] E1 = E CMAS

[0097]

[0098]

[0099] α1 = α CMAS

[0100] α2 = α pen = fα CMAS +(1 - f)α TBC

[0101] α3 = α TBC

[0102] where f = w / (d + w), d is the width of a single column of the columnar structure of the coating, and w is the spacing between adjacent columns.

[0103] The residual stress of each layer at the coating peeling position can be expressed as:

[0104]

[0105] Wherein, ε res is the residual strain of the peeled material.

[0106] Meanwhile, since the peeled layers of materials are traction - free, according to the force balance requirement, there is:

[0107]

[0108] In step 5, based on the internal damage value of the thermal barrier coating obtained in step 4, the reliability of the thermal barrier coating is predicted. During the prediction process, the average surface damage value of the blade coating is obtained from the internal damage value of the thermal barrier coating, and the damage situation of the thermal barrier coating under different particle sizes and service times is judged by combining the internal damage value of the thermal barrier coating, so as to realize the prediction of the service reliability of the thermal barrier coating on the turbine blade under different dust-containing environments and service times.

[0109] In this embodiment, the prediction results are presented in the form of a distribution map, so as to more intuitively show the influence of different particle sizes of particles serving for different times on the reliability of the thermal barrier coating.

[0110] During the simulation process, the gas and cold air flows are three-dimensional steady compressible flows. Considering the flow heat transfer between the gas and cold air and the blade and the heat conduction factor inside the blade, the gas and cold air satisfy the mass conservation, momentum conservation and energy conservation during the flow process. The Reynolds-averaged Navier-Stokes equations for compressible gases are used to describe the fluid flow and heat transfer inside the engine. The control equations for the gas and cold air are as follows:

[0111] Continuity equation:

[0112]

[0113] Momentum equation:

[0114]

[0115] Energy equation:

[0116]

[0117] In the formula, ρ is the fluid density, v is the velocity, p is the pressure, ν is the viscosity, h is the total entropy per unit mass, λ is the fluid thermal conductivity, T is the temperature, τ is the viscous stress tensor, and its components can be expressed as:

[0118]

[0119] In the formula, μ is the dynamic viscosity, s ij is the component of the deformation velocity tensor, ν k is the fluid turbulent kinematic viscosity, δ ij is the Kronecker delta function.

[0120] For the coupled heat transfer problem, the conditions are satisfied at the fluid-solid interface:

[0121] T s = T l

[0122]

[0123] wherein, T s and T l respectively represent the wall temperatures of the solid and the fluid, and n represents the normal direction, that is, temperature continuity and heat flux conservation are satisfied at the fluid-solid interface.

[0124] Meanwhile, the pressure inlet boundary condition is adopted at the mainstream inlet, and the pressure outlet boundary condition is adopted at the outlet; the numerical calculation adopts the coupled calculation of the pressure field and the velocity field, and the discrete formats of the convection term and the diffusion term are both second-order upwind. When the residuals of each item are less than 10 -4 , it can be regarded that the calculation converges.

[0125] The simulation results of the coating damage of 4-μm particles in this embodiment under different service times are as Figure 4 shown. The dotted line (X / L = 0) in the figure represents the dividing line between the pressure surface and the suction surface at the leading edge. When X / L is from 0 to 1, it represents the suction surface of the blade, and when X / L is from -1 to 0, it represents the pressure surface of the blade. It can be seen from the figure that the damage of the thermal barrier coating on the suction surface of the blade is small, and the damage is mainly concentrated at the leading edge and the area near the trailing edge of the pressure surface. At 1 h, the average surface damage value of the blade coating is only 0.0006, and it can be considered that the coating is basically not damaged; at 3 h, the average surface damage value is 0.01, and the increase rate is slow; at 6 h, the damage value in the area near the trailing edge of the leading edge and the pressure surface increases rapidly, and the maximum value reaches 0.84, and the average surface damage value reaches 0.1; at 10 h, the average surface damage value reaches 0.4, and the damage value in the area near the trailing edge of the leading edge and the pressure surface reaches 1, that is, the thermal barrier coating peels off and fails.

[0126] The simulation results of the coating damage of particles with different particle sizes in this embodiment under 6-h service are as Figure 5 shown. It can be seen from the figure that the particles with a particle size of 2 μm cause little damage to the coating. After 6 h of service, the average surface damage value is only 0.01. As the particle size increases, the damage at the area near the trailing edge of the leading edge and the pressure surface increases rapidly, and the average surface damage value also increases rapidly; when the particle size increases from 2 μm to 8 μm, the average surface damage value rapidly increases from 0.01 to 0.77. When the particle size increases from 8 μm to 12 μm, the growth rate of the average surface damage value slows down significantly, and it gradually approaches 1 as the particle size increases.

[0127] The present invention constructs a thermo-mechanical coupling model for the failure of the thermal barrier coating under CMAS deposition by calculating the CMAS deposition thickness and penetration depth, combining the energy release rate calculation formula and the internal damage calculation formula, and can simulate the influence of different particle sizes of particles serving for different times on the reliability of the thermal barrier coating under different particle concentrations, and obtain the particle deposition rate, deposition thickness, energy release rate of the thermal barrier coating and coating damage in different dusty service environments, thereby overcoming many defects in the prior art such as time-consuming and laborious experiments, large experimental measurement errors, and inability to replicate experimental conditions.

[0128] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A reliability prediction method for thermal barrier coatings deposited by CMAS, characterized in that: include: Step 1: Divide the turbine blade component and cascade channel model into tetrahedral meshes, perform mesh independence verification, establish the turbine blade component and cascade channel mesh model, and then import the turbine blade component and cascade channel mesh model into Fluent. According to the typical operating conditions of the aircraft engine, set the numerical calculation boundary conditions to obtain the turbine blade temperature distribution; Step 2: Establish a particle deposition model, obtain the number of particles deposited on the surface of the thermal barrier coating through the particle deposition model, and then obtain the particle deposition thickness on the surface of the thermal barrier coating according to the number of particles deposited on the surface of the thermal barrier coating; Step 3: Based on the temperature distribution of the turbine blade obtained in step 1 and the particle deposition thickness on the surface of the thermal barrier coating obtained in step 2, the CMAS penetration depth on the surface of the thermal barrier coating is obtained; Step 4: According to the thermal barrier coating particle deposition thickness obtained in step 2 and the CMAS penetration depth of the thermal barrier coating surface obtained in step 3, the internal energy release rate of the thermal barrier coating surface is calculated by the energy release rate calculation formula, and then the internal energy release rate of the thermal barrier coating surface is calculated by the internal damage calculation formula to obtain the internal damage value of the thermal barrier coating surface, that is, the internal damage value distribution of the thermal barrier coating; Step 5: Predict the reliability of the thermal barrier coating by using the internal damage value of the thermal barrier coating obtained in step 4, and output the corresponding prediction results; The energy release rate calculation formula is specifically: Where i=1, 2, 3 represent CMAS layer, CMAS penetration layer and TBC layer respectively, h i Indicates the depth of each layer, E i represents the Young's modulus of each layer, σ i It represents the in-plane residual stress generated by thermal expansion mismatch in each layer. Indicates the residual stress of each layer at the coating peeling point.

2. The reliability prediction method of thermal barrier coating under CMAS deposition according to claim 1, characterized in that: The specific steps of step 2 include: Step 2.1: Establish the UDF of the deposition mechanism and calculate the critical velocity through the UDF of the deposition mechanism; Step 2.2: Calculate the normal and tangential velocities of the particles after the collision by using the velocity formulas before and after the particle collision, and then calculate the angle of the particles after the collision by using the normal and tangential velocities after the particle collision; Step 2.3: Compare the critical speed with the normal speed of the particle after collision. If the normal speed of the particle after collision is greater than the critical speed, the particle will rebound and no deposition will occur. Go to step 2.

4. If the normal speed of the particle after collision is greater than the critical speed, the particle will adhere to the wall and deposition will occur. Step 2.4: Repeat steps 2.2 to 2.3 until the particles no longer collide with the thermal barrier coating on the blade surface; Step 2.5: After the above steps are completed, the deposited particles are counted to obtain the number of particle deposition, and then the particle deposition thickness on the surface of the thermal barrier coating is calculated based on the number of particle deposition.

3. The reliability prediction method of thermal barrier coating under CMAS deposition according to claim 2, characterized in that: The UDF of the deposition mechanism is specifically: Where V cr is the critical speed, E is the Young's modulus of the composite material, E s is the surface Young's modulus, E p is the Young's modulus of the particle, which satisfies E P =E0·e -aT ,ν s is the surface Poisson's ratio, ν p is the particle Poisson's ratio, D p is the particle radius, and ρ is the particle density.

4. The reliability prediction method of thermal barrier coating under CMAS deposition according to claim 2, characterized in that: The velocity formula of the particles before and after collision is specifically: In the formula, v 1n , v 2n and v 1t ,v 2t are the normal and tangential velocities of the particle before and after collision, respectively, and β1 is the angle between the velocity of the particle before collision and the tangential direction of the wall.

5. The reliability prediction method of thermal barrier coating under CMAS deposition according to claim 2, characterized in that: The specific calculation formula for the particle deposition thickness is: Where h is the deposition thickness / m, m is the particle deposition mass of the current grid / kg, and s is the current deposition grid area / m 2 .

6. The reliability prediction method of thermal barrier coating under CMAS deposition according to claim 1, characterized in that: The internal damage calculation formula is: Where D is the internal damage value of the coating. The value range of D is 0 to 1. The larger the D value, the greater the coating damage. When the D value reaches 1, the coating is considered to be failed. ss is the energy release rate / J·m -2 , a, b are fitting parameters.

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