Thermal analysis method for heterogeneous material assembly considering multi-scale contact thermal resistance

Abstract

The application discloses a thermal analysis method of a heterogeneous material combined component considering a multi-scale contact thermal resistance, and belongs to the technical field of aero-engine thermal management. Firstly, a periodic calculation model of a CMC outer ring and a metal casing combined component is established; secondly, the anisotropy of CMC heat conduction is set according to the geometric surface change of the gas outer ring; finally, in the CFD calculation, the empirical relationship of the contact thermal resistance is introduced by setting the equivalent heat conduction of the contact area between the CMC outer ring and the metal casing, the difference between the combined components with and without the contact thermal resistance is explored by comparing the temperature field results, and the influence of the contact thermal resistance on the flow heat exchange is explored. The method studies the influence of the contact thermal resistance on the turbine flow heat exchange result by considering the multi-scale contact thermal resistance between different materials, simultaneously corrects the temperature field of the turbine component in the CFD calculation, and provides a guidance basis for improving the prediction precision of the temperature result of the gas turbine component under complex gas-thermal load.

Description

Technical Field

[0001] This invention relates to the field of thermal management technology for aero-engines, and in particular to a thermal analysis method for heterogeneous material composite components that takes into account multi-scale contact thermal resistance. Background Technology

[0002] As a type of fiber-reinforced composite material, ceramic matrix composites (CMCs) exhibit significant anisotropy in thermal conductivity due to the microstructural characteristics of their toughening fibers, resulting in a marked difference between the axial and radial thermal conductivity. Furthermore, the heterogeneous structural features within CMCs, such as the arrangement and weaving of the internal fiber bundles, contribute to the significant structural effects of this anisotropy. The coupling effect between the anisotropy of CMC thermal conductivity and the spatially twisted surface of hot-end components, as well as the gas-solid coupling heat transfer under the thermal protection measures of the cooling structure, present new challenges to the thermal analysis of CMC hot-end components. Moreover, under the complex thermal loads of aero-engines, the differences in thermal response rates and coefficients of thermal expansion between the CMC outer ring and the metal casing lead to thermal expansion mismatch and localized thermal stress concentration in the combined component during engine operation. Therefore, research is needed on thermal matching design methods for the combined CMC outer ring and metal casing.

[0003] The fibrous braided structure of CMC results in a significant anisotropy in its thermal conductivity, in stark contrast to the homogeneous thermal conductivity of nickel-based alloys. This fundamental difference in material properties can lead to interfacial thermal mismatch under transient engine conditions. For example, during the rapid temperature rise at the turbine inlet during takeoff, the difference in the coefficients of linear expansion between the CMC outer ring and the metal casing will cause the interfacial shear stress to exceed the brazing layer's bearing capacity limit. This thermo-mechanical coupling failure mode has become a bottleneck problem restricting the engineering application of CMC / metal heterostructure components.

[0004] Current thermal analysis methods have significant limitations when dealing with such heterogeneous material combinations. Traditional finite element models based on homogenization assumptions struggle to capture the differences in fiber / matrix heat conduction paths at the microscale of CMCs. Studies show that ignoring the anisotropic thermal conductivity caused by the braided structure can lead to temperature field prediction errors as high as 21.78 K. For example, when the outer ring of the high-pressure turbine in the LEAP-X engine uses a 2.5-dimensional braided CMC, its radial heat flux density distribution exhibits asymmetric characteristics due to the interlacing angle of the fiber bundles. Existing commercial software often uses equivalent orthogonal anisotropic models for simplification, resulting in a 18% distortion rate in the predicted thermal gradient around the cooling holes. An even more serious challenge comes from the multi-physics coupling at the material interface. Creep-oxidation synergistic damage to the diffusion bonding layer at high temperatures dynamically changes the interfacial contact thermal resistance. NASA research indicates that this parameter can increase by 300% after 1000 hours of service at 1000°C, significantly affecting the overall heat flux distribution. These problems make it difficult for thermal analysis models based on the macroscopic continuous medium assumption to accurately predict the life-cycle performance degradation of heterogeneous components.

[0005] To address these challenges, breakthroughs have been achieved in multi-scale thermal analysis techniques in recent years. By combining micro-CT reconstructed mesoscopic geometric models with macroscopic heat transfer equations, researchers have established multi-level heat conduction models ranging from fiber bundle scale (~10 μm) to component scale (~1 m). For example, at the Asheville CMC production facility, GE used the Representative Volume Unit (REV) method to simulate the thermal response of 3D braided CMC, finding that the mesoscopic yarn arrangement leads to an "oscillating decay" characteristic in the thickness-direction temperature gradient, a phenomenon that was completely smoothed in the homogenized model. Meanwhile, a novel thermal metamaterial theory based on the inverse design principle provides a new approach to interfacial thermal adaptation. By designing a gradient anisotropic thermally conductive layer, heat flow redistribution at the CMC / metal interface can be achieved; experiments show that this method can reduce peak thermal stress by 42%. In China, the AVIC Commercial Aircraft Engine Group has developed a multi-scale coupled model considering the evolution of micropores in the diffusion bonding layer by integrating process simulation and thermodynamic analysis, successfully improving the prediction accuracy of thermal deformation of turbine stator components to 92%. These technological advancements have laid the theoretical foundation for establishing a high-fidelity thermal analysis system for heterogeneous materials, but how to achieve full-link digital mapping of manufacturing defects, microstructure, and macroscopic properties remains a core challenge that urgently needs to be overcome. Summary of the Invention

[0006] This invention provides a thermal analysis method for heterogeneous material composite components that considers multi-scale contact thermal resistance, solving the problem of difficulty in accurately predicting the contact thermal resistance of ceramic matrix composite (CMC) and high-temperature alloy (GH4169) interfaces in aero-engines due to the multi-scale roughness characteristics.

[0007] This invention provides a thermal analysis method for heterogeneous material composite components considering multi-scale contact thermal resistance, comprising the following steps:

[0008] Step 1: Based on the actual situation of the internal cooling structure of the gas turbine, while retaining the actual contact characteristics of the ceramic matrix composite outer ring and the metal casing assembly, a periodic calculation model of the ceramic matrix composite outer ring and the metal casing assembly is constructed, and meshing is performed.

[0009] Step 2: Extract the profile of the outer ring of the ceramic matrix composite material, and set a curve coordinate system in Fluent so that the thermal anisotropy of the ceramic matrix composite material changes with the outer ring profile.

[0010] Step 3: Calculate the contact area thermal resistance under the corresponding working conditions based on the empirical relationship between the contact thermal resistance of ceramic matrix composites and high-temperature alloys, and then convert it into the corresponding thermal conductivity and wall thickness in Fluent settings.

[0011] Step 4: Compare the temperature field results of the ceramic matrix composite outer ring and metal casing assembly with and without thermal resistance, and verify the thermal analysis method based on the difference in temperature field results with and without thermal resistance.

[0012] Optionally, in one embodiment of the present invention, in step 1, the connection form between the outer ring of the ceramic matrix composite material and the metal casing is analyzed with reference to the gas turbine model structure. Under the premise of retaining the internal cooling structure and contact form of the gas turbine, the entire ring model is periodically divided. At the same time, the mesh division method is selected based on the wall comprehensive cooling effect through mesh independence verification.

[0013] Optionally, in one embodiment of the present invention, in step 1, the ceramic matrix composite outer ring and metal casing combined component is divided into 1 / 9 of the cycle of the whole ring structure and divided using a polyhedral mesh, wherein the minimum mesh size is 0.1 mm, the maximum mesh size is 3.0 mm, the boundary layer type is selected as uniform, the height of the first layer mesh is set to 0.003 mm, and the number of meshes in the combined component is 7,652,512.

[0014] Optionally, in one embodiment of the present invention, in step 2, the UDF function in Fluent software is used to read the coordinates of geometric points on the outer ring profile, the normal direction of the outer ring surface is obtained through the geometric point coordinates, and the coordinate transformation between the global coordinate system and the local coordinate system is completed, thereby constructing the corresponding curvilinear coordinate system. Finally, the curvilinear coordinate system is used to realize the change of the thermal conductivity anisotropy of the outer ring of the ceramic matrix composite material with the outer ring profile.

[0015] Optionally, in one embodiment of the present invention, in step 3, the axial and normal thermal conductivity of the fiber bundle are characterized by orthogonal anisotropic material parameters, the fiber region is divided by a structured hexahedral mesh, and the empirical relationship between the microscopic equivalent contact thermal resistance and temperature and pressure is embedded into the microscopic interface of the microscopic contact thermal resistance model using an Abaqus user subroutine. The local thermal resistance at the contact interface is dynamically calculated based on the node temperature and pressure and mapped to the contact heat transfer coefficient. The air gap conduction and radiation heat transfer in the non-contact region are superimposed to obtain the final total heat transfer coefficient. The contact thermal resistance value under the corresponding conditions is obtained through the total heat transfer coefficient, and then it is equivalent to the wall thickness and thermal conductivity of the contact surface between two heterogeneous materials in Fluent software, thereby completing the introduction of contact thermal resistance.

[0016] Optionally, in one embodiment of the present invention, in step 4, the temperature field results of the ceramic matrix composite outer ring and metal casing assembly with and without thermal resistance are calculated using Fluent software. By comparing the corresponding temperature cloud maps, the temperature results on the characteristic lines are extracted and compared to determine the influence of contact thermal resistance on the flow heat transfer of the gas turbine components.

[0017] The thermal analysis method for heterogeneous material composite components considering multi-scale contact thermal resistance in this invention studies the influence of contact thermal resistance on turbine flow heat transfer results by considering the multi-scale contact thermal resistance between different materials. At the same time, it corrects the temperature field of turbine components in CFD calculations, providing guidance for improving the prediction accuracy of gas turbine component temperature results under complex gas thermal loads.

[0018] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0020] Figure 1 A flowchart of a thermal analysis method for a heterogeneous material composite component considering multi-scale contact thermal resistance according to an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of the calculation model of the combined components according to an embodiment of the present invention;

[0022] Figure 3 This is a schematic diagram of the mesh division of the combined components according to an embodiment of the present invention;

[0023] Figure 4 (a) and (b) are schematic diagrams of the thermal conductivity changes in the in-plane and thickness directions of the CMC outer ring thermal conductive surface in an embodiment of the present invention, respectively.

[0024] Figure 5 (a) and (b) are local temperature cloud diagrams of the axial section of the combined component with and without thermal resistance under the maximum takeoff condition of the present invention, respectively.

[0025] Figure 6 (a) and (b) are local cloud maps of the CMC outer ring hot wall surface temperature under the maximum takeoff condition with and without thermal resistance, respectively, according to the embodiments of the present invention.

[0026] Figure 7 This refers to the temperature change on the feature line of the combined component under conditions of thermal resistance and non-thermal resistance in an embodiment of the present invention. Detailed Implementation

[0027] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0028] Figure 1 This is a flowchart illustrating a thermal analysis method for heterogeneous material composite components considering multi-scale contact thermal resistance according to an embodiment of the present invention.

[0029] like Figure 1 As shown, the thermal analysis method for heterogeneous material composite components considering multi-scale contact thermal resistance includes the following steps:

[0030] Step 1: Referring to the actual situation of the internal cooling structure of the gas turbine, and while retaining the actual contact characteristics of the outer ring and casing assembly, calculate the periodicity of the CMC outer ring and metal casing assembly and divide the corresponding mesh.

[0031] Step 2: By extracting the profile of the outer ring of the CMC, a curve coordinate system is set in Fluent to make the thermal anisotropy of the CMC change with the profile of the outer ring.

[0032] Step 3: Calculate the contact area thermal resistance under the corresponding working conditions using the empirical formula for the contact thermal resistance between CMC and high-temperature alloy, and then convert it into the corresponding thermal conductivity and wall thickness in Fluent settings.

[0033] Step 4: Compare the temperature field results of the combined components with and without thermal resistance, and verify the corresponding thermal analysis method by studying the differences between the two.

[0034] In an embodiment of the present invention, in step 1, referring to the actual gas turbine model structure and analyzing the connection form between the outer ring and the casing, to reduce the computational resource consumption required in the simulation, the entire ring model is periodically divided while retaining the internal cooling structure and contact form of the turbine. Simultaneously, a suitable mesh generation method is selected based on the wall-comprehensive cooling effect, verified by mesh independence.

[0035] In an embodiment of the present invention, in step 1, the composite component is divided into 1 / 9 of the cycle of the complete ring structure, and a polyhedral mesh is used for this division. The minimum mesh size is 0.1 mm, and the maximum size is 3.0 mm. The boundary layer type is selected as uniform, and the height of the first layer mesh is set to 0.003 mm. The number of meshes for the composite component is 7,652,512.

[0036] In an embodiment of the present invention, in step 2, the UDF function in Fluent software is used to create a set of curved coordinate systems based on the geometric changes of the outer ring component, and the curved coordinates are used to realize the thermal anisotropy of the CMC outer ring as the outer ring surface changes.

[0037] Specifically, using the UDF function in Fluent software, the coordinates of geometric points on the outer ring profile are read. The normal direction of the outer ring surface is obtained through the geometric point coordinates, and the coordinate transformation between the global coordinate system and the local coordinate system is completed, thereby constructing the corresponding curvilinear coordinate system. Finally, the curvilinear coordinate system is used to realize the change of thermal conductivity anisotropy of the outer ring of the ceramic matrix composite material with the outer ring profile.

[0038] In an embodiment of the present invention, in step 3, the axial and normal thermal conductivity of the fiber bundle are characterized by orthogonal anisotropic material parameters. The fiber region is divided by a structured hexahedral mesh. An empirical relationship between the microscopic equivalent contact thermal resistance and temperature and pressure is embedded into the microscopic interface of the microscopic contact thermal resistance model using an Abaqus user subroutine. The local thermal resistance at the contact interface is dynamically calculated based on the node temperature and pressure and mapped to the contact heat transfer coefficient. The air gap conduction and radiation heat transfer in the non-contact region are superimposed to obtain the final total heat transfer coefficient. The contact thermal resistance value under the corresponding conditions is obtained through the total heat transfer coefficient. Then, in Fluent software, it is equivalent to the wall thickness and thermal conductivity of the contact surface between two heterogeneous materials, thereby completing the introduction of contact thermal resistance.

[0039] In an embodiment of the present invention, in step 3, the controlled displacement method involves fixing the displacement of the lower surface of the high-temperature alloy, constraining the lateral displacement of the upper surface of the CMC, and applying a normal displacement load to the upper surface of the CMC to achieve equivalent pressure. The temperature-displacement coupled transient calculation adopts an explicit dynamic algorithm, and the equivalent pressure loading is achieved through quasi-static step size control. The contact algorithm selects surface-to-surface contact. The peak position of the contact pressure and the proportion of the contact area are extracted through multi-scale displacement distribution, and the attenuation law of the temperature gradient in the contact area with the increase of pressure is obtained by combining the temperature field analysis.

[0040] In an embodiment of the present invention, in step 4, Fluent software is used to calculate the temperature field results of the combined components with and without thermal resistance, taking the maximum takeoff condition as an example. By comparing the corresponding temperature cloud maps, the temperature results on the characteristic lines are extracted and compared to explore the influence of contact thermal resistance on the flow heat transfer of the turbine components.

[0041] The following detailed description of the thermal analysis method for the ceramic matrix composite outer ring and metal casing assembly considering multi-scale contact thermal resistance of the present invention will be provided through specific embodiments.

[0042] In an embodiment of the present invention, in step 1, referring to the actual gas turbine structure, a calculation model of the CMC outer ring / metal casing composite component was constructed using UG software. The composite component has a cycle of 1 / 9 of the entire ring structure, and the corresponding impact hole arrangements are 2×6, 2×6, 1×8, and 1×8, as shown below. Figure 2 As shown. To reduce the computational resource consumption required in the simulation, the entire ring model is periodically divided while retaining the internal cooling structure and contact form of the turbine. Simultaneously, based on the wall-comprehensive cooling effect and through mesh independence verification, a suitable meshing method is selected, using a polyhedral mesh with a minimum mesh size of 0.1 mm and a maximum size of 3.0 mm. The boundary layer type is selected as uniform, with 8 boundary layers and the first layer mesh height set to 0.003 mm. Since the simulation involves the handling of the transition-to-static interface, local mesh refinement is required at the interface. The mesh size of the composite component is 7,652,512, and the final mesh is shown below. Figure 3 As shown.

[0043] In an embodiment of the present invention, in order to realize that the thermal conductivity of the outer ring of the gas changes with the geometric surface in step 2, this paper uses the UDF function of FLUENT to realize the anisotropic setting of the thermal conductivity of the outer ring of the gas. The following is the code design principle.

[0044] Considering the structure and anisotropic characteristics of CMC materials, it is unreasonable to set a global thermal conductivity when introducing thermal conductivity for solids. The direction of thermal conductivity of the outer ring of the CMC changes with the shape, so a coordinate transformation between the global and local coordinate systems is required when introducing thermal conductivity, based on the normal direction of the outer ring surface. In the local coordinate system, the thermal conductivity along the axial direction of the outer ring is considered a constant, while the thermal conductivity along the radial direction and another in-plane direction are also considered constant. The coordinate transformation formula is shown below:

[0045] B = P^(-1)AP

[0046] Where B is the thermal conductivity matrix in the principal coordinate system, and A is the thermal conductivity matrix in the local coordinate system. P is the transition matrix between the principal and local coordinate systems. According to matrix theory, the value of matrix P depends only on the angle between the basis vectors of the two coordinate systems. Assuming the global coordinate system is formed by rotating the local coordinate system around the X-axis by an angle α, then around the Y-axis by an angle β, and finally around the Z-axis by an angle γ (where counterclockwise is positive and clockwise is negative), then the direction cosine matrix P of the coordinate system rotation is:

[0047]

[0048] Since the direction of the outer toroidal normal vector cannot be extracted temporarily, the deflection angle of the center point coordinates of each grid cell in the outer ring is approximately calculated using the coordinates of the three outer spiral lines used in the outer ring design as input when writing the UDF. During the calculation, the Z-axis coordinate is removed from the outer spiral line point coordinates, assuming that the global and local coordinates rotate only around the Z-axis (the Z-axis vector direction is the outer ring axial vector), transforming the 3D curve into a 2D curve. Then, the angle between the local coordinate system and the principal coordinate system at each coordinate point is calculated using the two points closest to that point. The final schematic diagram of the CMC outer ring heat conduction change is shown below. Figure 4 As shown.

[0049] In an embodiment of the present invention, the research scheme for the local contact thermal resistance prediction method of CMC outer ring / metal casing in step 3 is as follows: for the different connection forms of the two-stage CMC outer ring and metal casing, the different contact forms between CMC material and metal material are extracted, and a cross-scale method is used to establish a CMC surface feature description model and its contact thermal resistance analysis model with metal material, to obtain the heat transfer mechanism of CMC / metal heteromaterial contact surface, and the influence law of contact surface roughness on contact thermal resistance.

[0050] The method for estimating the contact thermal resistance of CMC and high-temperature alloys differs from the traditional method for calculating contact thermal resistance. Traditional methods for studying material contact thermal resistance can use models of small regions to represent the macroscopic contact characteristics of the material. However, the surface of woven CMC has obvious macroscopic and microscopic woven texture structures, with warp and weft yarns interlacing. Furthermore, due to the inconsistency of processing technology, the distribution of the surface matrix is ​​not entirely the same. These characteristics create the woven periodic characteristics of the CMC surface. If the periodic structure is scanned to calculate the contact thermal resistance, the number of discrete points scanned is on the order of magnitude, making the calculation process very slow and complex. Moreover, local small regions cannot cover the entire contact characteristics of CMC.

[0051] Considering the periodic characteristics of the woven texture on the surface of CMC, a multi-scale contact thermal resistance analysis method is required. First, the surface morphology is scanned to identify convex regions where contact is certain. The minimum RVE modeling criterion is determined by comparing the surface morphology with the overall roughness characterization of these convex regions, establishing a contact thermal resistance analysis model at the microstructural level to obtain the contact thermal conductivity of these regions. Next, a minimum woven period RVE model of the macro- and micro-scale visualized CMC is established. Using explicit kinetic analysis, the CMC is brought into contact with a high-temperature alloy model of the same size. A thermo-mechanical coupling analysis method is employed. The contact thermal resistance of the CMC convex regions is introduced from the numerical calculation results of the microstructural contact thermal conductivity. For other non-contact regions, only air gap heat transfer and radiative heat transfer are considered to obtain the contact thermal resistance between the woven CMC RVE model and the high-temperature alloy. Finally, a macroscopic temperature field analysis model is introduced. The calculation accuracy of the multi-scale CMC-high-temperature alloy contact thermal resistance prediction method is verified by comparing it with traditional hypothetical calculation methods for thermally thin structures and experimentally measured contact thermal resistance data.

[0052] In an embodiment of the present invention, step 4 compares the temperature field distribution characteristics of the combined components with and without thermal resistance. After correction by introducing the empirical relationship of contact thermal resistance, a significant temperature distinction appears in the contact area between the metal casing and the outer ring of the CMC due to the presence of thermal resistance. After statistically analyzing the highest and lowest temperatures of the casing and the outer ring, it was found that—considering contact thermal resistance, the temperature change of the outer ring of the CMC is smaller, but the temperature change of the metal casing is larger, the high temperature of the metal casing wall is significantly reduced, and the overall temperature gradient of the casing is lowered. Taking the maximum takeoff condition as an example, a comparative analysis of the temperature results before and after introducing contact thermal resistance is performed: Figure 5 A comparison of temperature contour maps of the combined components shows that after introducing a multi-scale contact thermal resistance analysis model, the temperature of the metal casing contact area decreases significantly, while the temperature of the outer ring contact area increases significantly. Without considering thermal resistance, the average temperature of the contact area between the casing and the CMC outer ring is 1199.39 K. After considering contact thermal resistance, the average temperature of the casing contact area is 1155.6 K, a decrease of nearly 40 K. However, considering thermal resistance, the corresponding temperature of the CMC outer ring contact area increases by 32.48 K. Figure 6The comparison of CMC outer ring hot wall surface temperatures with and without thermal resistance shows that the presence of contact thermal resistance limits the low-temperature thermal conductivity of the metal casing, resulting in a higher temperature in the contact area between the outer ring cold wall surface and the metal casing. At the trailing edge of the outer ring hot wall surface, the area covered by the local high-temperature region is slightly increased due to the influence of the cold wall surface contact thermal resistance. The presence of contact thermal resistance significantly affects the temperature of the contact area between the outer ring and the casing, but its impact on the overall temperature distribution trend of the outer ring is relatively small due to the limited contact area. Specifically, considering thermal resistance, the average temperature of the CMC outer ring hot wall surface increased by 2.44 K, and the average temperature of the cold wall surface increased by 10.72 K. Figure 7 As shown, after the thermal resistance is introduced into the temperature field of the composite component, a significant temperature jump and drop occur in the contact area between the CMC outer ring and the metal casing. Because the thermal resistance hinders heat conduction between solids, the temperature of the contact area in the metal casing is lower, while the temperature of the corresponding area of ​​the CMC outer ring is significantly higher.

[0053] The thermal analysis method for heterogeneous material composite components considering multi-scale contact thermal resistance proposed in this invention first establishes a periodic calculation model of the composite component consisting of a CMC outer ring and a metal casing. Second, it sets the anisotropy of CMC thermal conductivity based on the geometric changes of the gas outer ring. Finally, in the CFD calculation, it introduces the empirical relationship of contact thermal resistance by setting the equivalent thermal conductivity of the contact area between the CMC outer ring and the metal casing. By comparing the temperature field results of the composite component with and without contact thermal resistance, the difference between the two is explored, and the influence of contact thermal resistance on flow heat transfer is investigated. This method, by considering the multi-scale contact thermal resistance between different materials, studies the influence of contact thermal resistance on turbine flow heat transfer results, and simultaneously corrects the temperature field of turbine components in the CFD calculation, providing guidance for improving the prediction accuracy of gas turbine component temperature results under complex gas thermal loads.

[0054] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0055] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0056] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

Claims

1. A thermal analysis method for heterogeneous material composite components considering multi-scale contact thermal resistance, characterized in that, Includes the following steps: Step 1: Based on the actual situation of the internal cooling structure of the gas turbine, while retaining the actual contact characteristics of the ceramic matrix composite outer ring and the metal casing assembly, a periodic calculation model of the ceramic matrix composite outer ring and the metal casing assembly is constructed and meshed. Step 2: Extract the profile of the outer ring of the ceramic matrix composite material, and set a curve coordinate system in Fluent so that the thermal anisotropy of the ceramic matrix composite material changes with the outer ring profile. Step 3: Calculate the contact thermal resistance under corresponding working conditions based on the empirical relationship between the contact thermal resistance of ceramic matrix composites and high-temperature alloys, and then convert it into the corresponding thermal conductivity and wall thickness in Fluent settings. Specifically, this includes: characterizing the axial and normal thermal conductivity of the fiber bundle through orthogonal anisotropic material parameters; dividing the fiber region through a structured hexahedral mesh; and using an Abaqus user subroutine to embed the empirical relationship between the microscopic equivalent contact thermal resistance and temperature and pressure into the microscopic interface of the microscopic contact thermal resistance model. At the contact interface, the local thermal resistance is dynamically calculated based on the node temperature and pressure and mapped to the contact heat transfer coefficient. Air gap conduction and radiation heat transfer are superimposed in the non-contact area to obtain the final total heat transfer coefficient. The contact thermal resistance value under corresponding conditions is obtained through the total heat transfer coefficient, and then converted into the wall thickness and thermal conductivity of the contact surface between the two heterogeneous materials in Fluent software, thus completing the introduction of contact thermal resistance. Step 4: Compare the temperature field results of the ceramic matrix composite outer ring and metal casing assembly with and without thermal resistance, and verify the thermal analysis method based on the difference in temperature field results with and without thermal resistance.

2. The method according to claim 1, characterized in that, In step 1, the connection between the ceramic matrix composite outer ring and the metal casing is analyzed by referring to the gas turbine model structure. While retaining the internal cooling structure and contact form of the gas turbine, the entire ring model is periodically divided. At the same time, the mesh generation method is selected based on the wall integrated cooling effect as a reference through mesh independence verification.

3. The method according to claim 1, characterized in that, In step 1, the ceramic matrix composite outer ring and metal casing combined component is divided into 1 / 9 of the cycle of the whole ring structure and divided using a polyhedral mesh. The minimum mesh size is 0.1 mm and the maximum mesh size is 3.0 mm. The boundary layer type is selected as uniform, the height of the first layer mesh is set to 0.003 mm, and the number of meshes in the combined component is 7,652,512.

4. The method according to claim 1, characterized in that, In step 2, the UDF function in Fluent software is used to read the coordinates of geometric points on the outer ring profile. The normal direction of the outer ring surface is obtained through the geometric point coordinates, and the coordinate transformation between the global coordinate system and the local coordinate system is completed, thereby constructing the corresponding curvilinear coordinate system. Finally, the curvilinear coordinate system is used to realize the change of the thermal conductivity anisotropy of the outer ring of the ceramic matrix composite material with the outer ring profile.

5. The method according to claim 1, characterized in that, In step 4, Fluent software is used to calculate the temperature field results of the ceramic matrix composite outer ring and metal casing assembly with and without thermal resistance. By comparing the corresponding temperature cloud maps, the temperature results on the characteristic lines are extracted and compared to determine the influence of contact thermal resistance on the flow heat transfer of the gas turbine components.

Images