Design method of turbine blade airfoil creep simulation component based on consistent sectional stress

Abstract

The present invention discloses a method for designing a turbine blade airfoil creep simulation part based on consistent cross-sectional stress, belonging to the field of aerospace engine technology. The method comprises the following steps: S1, determining the dangerous parts and dangerous sections of the turbine blade, and extracting the stress distribution on the dangerous section of the turbine blade; S2, obtaining the blade profile parameters and stress characteristics of the dangerous section based on the stress distribution on the dangerous section of the turbine blade, and establishing a simulation part test section consistent with the dangerous section blade profile; S3, using the simulation part test section as the mid-section, stretching the mid-section to form the simulation part body; S4, performing variable cross-section optimization on the simulation part body to reduce stress concentration in the transition section of the simulation part body; S5, based on the simulation part body after variable cross-section optimization, respectively providing clamping sections at both ends of the simulation part body to form a blade airfoil creep simulation part. The present application has the advantage of being able to fully reflect the stress state of the real component.

Description

Technical Field

[0001] The present invention relates to the technical field of aerospace engines, and in particular to a method for designing creep simulation parts of turbine blade airfoils based on consistent cross-sectional stress. The method is a method for designing creep simulation parts that can take into account the force characteristics and stress distribution of the blade airfoil cross-section. Background Art

[0002] With the continuous improvement of aircraft engine performance and the requirement for long-duration service, turbine blades inevitably experience various damage behaviors such as creep under high temperatures, high centrifugal loads, and long periods of time. As a result, turbine blades have a short lifespan and poor reliability, and their lifespan seriously restricts the lifespan of the entire engine. Under typical operating conditions, turbine blades face the risk of creep failure due to the high temperature and stress levels in the blade body. Due to the high cost of real blade testing, it is difficult to conduct large-scale testing in the early stages of design. Material-level testing based on standard parts cannot reflect the force characteristics and stress distribution of real components, making it impossible to characterize the creep failure behavior of turbine blades. Therefore, it is of great significance to propose a design method for turbine blade body creep simulation based on consistent cross-sectional stress.

[0003] With the continuous development of structural strength design technology, some preliminary results have been achieved in this technical field, but the following problems still exist: 1) Equivalent stress is often used as a damage control parameter in the design process, which cannot reflect the complex stress state of real turbine blades during service; 2) For simplicity, notched test pieces are usually used to simulate the stress distribution of real blades, but due to the large differences in geometric shapes, it is difficult to reflect the actual stress state.

[0004] Existing patent CN 201710255317.3, "A Test Method for Blade Structure Simulators," discloses a design method for blade airfoil simulators with identical damage location shapes, identical or similar stresses, and stress distributions. This method applies loads and temperatures at critical blade sections to the simulators, conducting fatigue, creep, and interaction life tests to assess the service life of turbine blades and reveal their damage failure mechanisms. This method uses equivalent stress as the damage control parameter, ignoring the bending moment acting on the blades. Previous studies have shown that turbine blades experience significant, non-negligible bending moments, making the use of cross-section normal stress as a more reasonable and accurate damage control parameter for simulator design.

[0005] The existing literature, "Study on Low-Cycle Fatigue / Creep Life of Aero-Engine High-Pressure Turbine Blades," proposes a design method for turbine blade simulation components based on geometric similarity and consistent stress and temperature distribution. The blade airfoil simulation utilizes a standard flat specimen with no bosses, but with a notch in the midsection to achieve stress distribution consistent with the actual component. The simulation's test geometry differs significantly from the actual turbine blade profile, and the notch fails to reflect the component's true stress state. Using the actual blade profile as the simulation component's test section and employing an eccentric clamping section design further aligns with actual conditions. Summary of the Invention

[0006] The present invention provides a turbine blade airfoil creep simulation component design method based on consistent cross-sectional stress, so as to overcome the problems in the prior art of turbine blade airfoil creep simulation component design that the creep simulation component cannot fully reflect the stress state of the real component.

[0007] According to one aspect of the present invention, a method for designing a creep simulation component of a turbine blade airfoil based on consistent cross-sectional stress is provided, comprising the following steps: S1, determining a dangerous portion and a dangerous cross-section of the turbine blade, and extracting stress distribution on the dangerous cross-section of the turbine blade;

[0008] S2, based on the stress distribution on the dangerous section of the turbine blade, obtain the blade profile parameters and stress characteristics of the dangerous section, and establish a simulation part assessment section consistent with the blade profile of the dangerous section;

[0009] S3, taking the simulated part test section as the middle section, stretching the middle section to form the simulated part body;

[0010] S4, optimizing the variable cross-section of the simulation body to reduce stress concentration in the transition section of the simulation body;

[0011] S5, based on the simulation part body after variable cross-section optimization, clamping sections are set at both ends of the simulation part body to form a blade body creep simulation part. The middle part of the simulation part body is the test section, and the clamping sections at both ends of the simulation part body are used for uniaxial tensile loading.

[0012] Optionally, step S5 also includes the following steps: adjusting the eccentricity of the clamping section according to the stress characteristics of the turbine blade obtained in step S2, so that the stress distribution of the test section of the simulation part is consistent with the stress distribution of the dangerous section of the turbine blade.

[0013] Optionally, in step S5: the clamping section is a threaded connection; after obtaining the blade and airfoil creep simulation part, a finite element static analysis model of the blade and airfoil creep simulation part is established; a finite element static analysis is performed on the model, and a strength check is performed under the assessment load and environment to ensure that the strength of the clamping section meets the standard.

[0014] Optionally, making the clamping section strength meet the standard means that the maximum stress of the clamping section of the blade airfoil creep simulation component is less than half of the stress of the test section.

[0015] Optionally, the blade profile parameters in step S2 include: cross-section outer boundary node coordinates, cross-section position, cross-section centroid and centroid coordinates, and cross-section area.

[0016] Optionally, the force characteristics in step S2 include a force perpendicular to the dangerous section and a bending moment in a non-vertical direction.

[0017] Optionally, in step S4, variable cross-section optimization refers to adopting a variable cross-section design to form a smooth and continuous variable cross-section body of the simulation body, and to ensure that the test cross-section of the simulation body is a dangerous cross-section during the test.

[0018] Optionally, step S4 also includes: establishing a transition platform of the simulation part with the centroid of the section as the center on the upper and lower sections of the simulation part body that has been optimized for variable section, as a transition section between the simulation part test section and the clamping section.

[0019] Optionally, in step S2, a simulation part assessment section consistent with the dangerous section blade is established, the boundary node coordinates of the dangerous section of the blade are imported into the three-dimensional modeling software UG, and the boundary scattered points of the dangerous section of the blade are fitted into a closed curve using the curve fitting command to form the assessment section.

[0020] Optionally, the specific steps of variable section optimization include: establishing a reference plane on the upper and lower sections of the simulation body, projecting the middle section onto the reference plane, using the scaling curve command to enlarge the section to 1.6 times with the center of mass of the section as the scaling center, and then using the curve group command to generate a smooth continuous variable section body through the three sections established above.

[0021] In summary, this application includes at least one of the following beneficial technical effects:

[0022] This patent uses the actual blade profile section as the test section. Through the variable section design, the fracture site of the test is located in the test area and stress concentration in the transition section and the clamping section is avoided, thereby ensuring the effectiveness and feasibility of the test. It also innovatively proposes that the upper and lower clamping sections of the simulation part adopt a deviated section centroid design under the premise of being coaxial, so as to realize the simulation part's response to the stress state of the actual turbine blade body, and ultimately meet the needs of turbine blade body creep test simulation.

[0023] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0025] Figure 1 is a flow chart of the present invention;

[0026] Figure 2 Schematic diagram of the dangerous section, the simulation part body and the blade creep simulation part of the present invention;

[0027] Figure 3 Schematic diagram of the strength verification of the blade body creep simulation component of the present invention. DETAILED DESCRIPTION

[0028] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0029] The following is combined with Figure 1-3 This application is described in further detail.

[0030] Reference Figure 1 and Figure 2 The present application discloses a method for designing a turbine blade airfoil creep simulation component based on consistent cross-sectional stress, comprising the following steps:

[0031] S1, determine the dangerous parts and dangerous sections of the turbine blade, and extract the stress distribution on the dangerous sections of the turbine blade;

[0032] S2, based on the stress distribution on the dangerous section of the turbine blade, obtain the blade profile parameters and stress characteristics of the dangerous section, and establish a simulation part assessment section consistent with the blade profile of the dangerous section;

[0033] S3, taking the simulated part test section as the middle section, stretching the middle section to form the simulated part body;

[0034] S4, optimizing the variable cross-section of the simulation body to reduce stress concentration in the transition section of the simulation body;

[0035] S5, based on the simulation part body after variable cross-section optimization, clamping sections are set at both ends of the simulation part body to form a blade body creep simulation part. The middle part of the simulation part body is the test section, and the clamping sections at both ends of the simulation part body are used for uniaxial tensile loading.

[0036] In the above scheme, by accurately acquiring and simulating the stress distribution of the turbine blade at the most critical section, this method can truly reflect the stress state of the blade under actual operating conditions, which is crucial for accurately predicting the blade's life and failure mode. The designed simulation component is highly consistent with the critical section of the actual turbine blade in terms of geometry and stress distribution, ensuring high reliability and representativeness of the test results. Through the variable cross-section design, this method reduces stress concentration in the transition section, and the optimized design helps to more realistically simulate the stress response of the blade in actual operation. The clamping section included in the design allows for uniaxial tensile testing, which is an effective way to evaluate the behavior and life of materials when subjected to loads similar to those in actual operation. Compared with existing technologies, this method can more accurately simulate complex stress states, reduce stress concentration in the transition section, and improve the representativeness and reliability of the test through the variable cross-section design.

[0037] Step S1 involves identifying and analyzing the most dangerous parts and sections of the turbine blades where creep or other forms of damage are most likely to occur, and extracting the stress distribution of these sections in detail. This step is the foundation of the entire simulation component design method, ensuring that the subsequent design is as consistent as possible with the actual working conditions. The specific steps include: using finite element analysis (FEA) to simulate the turbine blades; applying loads under actual operating conditions to the finite element model, including but not limited to temperature distribution, centrifugal force, aerodynamic loads, etc.; after the simulation is completed, analyzing the stress distribution of various parts on the turbine blades; based on the stress analysis results, selecting the section with the highest stress as the dangerous section for further analysis.

[0038] The blade profile parameters in step S2 include: cross-section outer boundary node coordinates, cross-section location, cross-section centroid and centroid coordinates, and cross-section area. The load characteristics in step S2 include forces acting perpendicular to the critical section and bending moments in non-perpendicular directions. The geometric and mechanical data collected in this step directly influence the design of the simulation component, ensuring that the simulation accurately reflects the actual operating conditions of the turbine blade during the experiment. The cross-section outer boundary node coordinates provide the precise geometric shape of the cross-section and are essential for replicating the critical section shape of the real blade. These coordinates are used to reconstruct a cross-section in the simulation component that is consistent with the real blade geometry, ensuring geometric similarity. The cross-section location determines the exact location of the cross-section in the simulation component, facilitating the correct placement of the test section in the simulation component design. The cross-section centroid and centroid coordinates provide the cross-section's mass and geometric center, which are crucial for determining the force application point in the simulation component and calculating the cross-section's dynamic behavior. The cross-section area directly affects the cross-section's load characteristics, including stress distribution and strength. Forces acting perpendicular to the critical section are the primary load directly affecting the cross-section's normal stress. Bending moments are extremely important for analyzing and designing the structural strength and stability of the simulation component. In actual operation, turbine blades are not only subjected to axial forces, but also moments that cause bending and torsion. The calculation of these bending moments ensures that the simulation can reproduce the structural response of the blades under actual working conditions in the experiment. By comprehensively utilizing these detailed blade parameters and force characteristics, the designed simulation can more accurately simulate the force environment of the turbine blades under actual operating conditions.

[0039] In step S2, establishing a test section of the simulation part that is consistent with the dangerous section blade profile means importing the boundary node coordinates of the dangerous section of the blade profile into the 3D modeling software UG, and using the curve fitting command to fit the boundary scattered points of the dangerous section of the blade profile into a closed curve to form the test section. Through the specific node coordinates obtained from the finite element analysis, this step ensures that the test section can accurately replicate the real turbine blade dangerous section in geometry. This precise geometric replication is the key to ensuring the validity of the simulation test results, because even small geometric differences may lead to significant changes in stress distribution and stress concentration points, thereby affecting the failure behavior of the simulation part; by using curve fitting technology, a smooth and continuous curve can be generated from the actual blade section scattered point data, which helps to achieve the same or similar stress distribution in the simulation part as the real blade. Such consistency is the basis for understanding and predicting the behavior of the blade under actual working conditions, ensuring that the data of the simulation test can effectively reflect the actual situation.

[0040] In a specific embodiment, the blade profile parameters are as shown in the following table.

[0041]

[0042] Table 1 Blade profile parameters and stress state of dangerous sections of turbine blade body

[0043] Step S3 is a key step in the design of turbine blade creep simulation parts. It involves using the test section obtained through precise modeling as the middle section, and then forming the main structure of the entire simulation part through stretching operations. This step ensures that the middle section geometry of the simulation part is consistent with the dangerous section of the real blade. Using the software stretching tool, the middle section is stretched along its normal direction (usually the length direction of the simulation part). The stretching length is determined according to the actual test requirements and the simulation part design specifications, and must be long enough for installation and testing. During the stretching process, the cross-sectional shape is kept unchanged to ensure that the middle section of the entire simulation part is completely consistent with the designed test section.

[0044] In step S4, variable-section optimization involves employing a variable-section design to create a smooth, continuously variable-section body within the simulator, ensuring that the tested section of the simulator is the critical section during the test. The specific steps for variable-section optimization include: establishing a reference plane on each of the upper and lower sections of the simulator body; projecting the midsection onto the reference plane; using the Scale Curve command to magnify the section by 1.6 times, with the centroid of the section as the scaling center; and finally, using the Through Curve Group command to generate a smooth, continuously variable-section body that passes through the three established sections.

[0045] Step S4 also includes: establishing a transition platform of the simulation part with the centroid of the section as the center on the upper and lower sections of the simulation part body that has been optimized for variable section, as a transition section between the simulation part test section and the clamping section.

[0046] The variable cross-section optimization design in step S4 is a key link in the development of turbine blade creep simulation parts. It optimizes the stress distribution by changing the cross-sectional shape of the simulation body, thereby simulating the blade behavior under more realistic working conditions. In any structural component, stress concentration is usually one of the main causes of fatigue and fracture. In the simulation part of the turbine blade, stress concentration may lead to inaccurate test results and fail to truly reflect the performance of the blade in actual operation. Through variable cross-section design, the geometry of the transition section can be optimized and stress concentration can be reduced, thereby more realistically simulating the actual working state of the blade; variable cross-section optimization ensures that the test section of the simulation part can maintain the same geometry as the original design even when under stress, which is crucial to ensuring the validity and reliability of the test data. By adjusting the cross-sectional size and shape, the deformation and stress path of the simulation part during loading can be more accurately controlled to ensure that the test section is always the dangerous section in the turbine blade design.

[0047] Step S5 also includes the following steps: adjusting the eccentricity of the clamping section according to the stress characteristics of the turbine blade obtained in step S2 so that the stress distribution of the test section of the simulation part is consistent with the stress distribution of the dangerous section of the turbine blade.

[0048] Reference Figure 3In step S5, the clamping section is threaded. After obtaining the blade airfoil creep simulation component, a finite element static analysis model of the blade airfoil creep simulation component is established. The model is subjected to finite element static analysis and strength verification is performed under the test load and environment to ensure that the clamping section strength meets the standard. Meeting the clamping section strength standard means that the maximum stress in the clamping section of the blade airfoil creep simulation component is less than half the stress in the test section.

[0049] In step S5, the clamping sections are respectively set at both ends of the simulation body, including the following steps: establishing a 50mm×50mm square sketch with the centroid of the section as the center on the upper and lower sections of the established variable-section body, rotating the square sketch around the center so that the section can completely cover the section, stretching the section 5mm in the normal direction to form a platform as a transition platform for the simulation, drawing a circular sketch with a diameter of φ16mm with the centroid of the section as the center on the transition platform, stretching it 25mm in the normal direction to generate the clamping section of the simulation; establishing a finite element static analysis model of the turbine blade creep simulation in ANSYS Workbench, and performing strength analysis on the model. According to the force characteristics of the actual blade part obtained in the second step, on the premise of ensuring that the upper and lower clamping sections of the simulation are coaxial, the center of the upper and lower clamping sections is deviated from the centroid of the blade section, and the eccentricity is continuously adjusted (such as Figure 3 As shown in the figure, the stress distribution of the simulated part in the assessment section is basically consistent or similar to the stress distribution of the real blade dangerous section, the maximum value of the normal stress on the section is the same, and the minimum value error is within 3%.

[0050] The design in step S5 focuses on ensuring the performance and safety of the creep simulator during the experiment. By installing clamping sections at both ends of the simulator body, using threaded connections, and performing finite element static analysis to verify strength, this design strategy provides a solid foundation for creep testing. The following is a detailed explanation of the specific role of this design:

[0051] To ensure the reliability and safety of the connection, threaded connections are a common mechanical connection method that provides a reliable and reusable connection, ensuring that the dummy component will not loosen or break at the clamping point under high stress and high temperature environments. Threaded connections facilitate quick installation and removal of the dummy component, making the testing process more efficient and facilitating replacement or adjustment of the dummy component. By building a finite element model, the dummy component's behavior during the experiment can be predicted without physical testing. This not only optimizes the design but also predicts potential failure modes, allowing for proactive design adjustments. According to design requirements, the maximum stress in the clamping section must be less than half the stress in the test section. This requirement ensures that the dummy component will not break unexpectedly in the clamping section during actual testing, focusing the testing on the test section, the simulated critical section. By strength-checking the clamping section, the entire system maintains structural integrity under the harshest test conditions, preventing potential hazards during testing. The key to the design of step S5 lies in ensuring the performance and safety of the dummy component during testing through precise mechanical connections and finite element analysis, thereby providing reliable data to support design optimization and life prediction of turbine blades. This approach significantly improves the accuracy and efficiency of creep testing through scientific design and analysis.

[0052] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A design method for a turbine blade airfoil creep simulation component based on consistent cross-sectional stress, characterized in that: The steps include: S1, determine the dangerous parts and dangerous sections of the turbine blade, and extract the stress distribution on the dangerous sections of the turbine blade; S2, based on the stress distribution on the dangerous section of the turbine blade, obtain the blade profile parameters and stress characteristics of the dangerous section, and establish a simulation part assessment section consistent with the blade profile of the dangerous section; S3, taking the simulated part test section as the middle section, stretching the middle section to form the simulated part body; S4, optimizing the variable cross-section of the simulation body to reduce stress concentration in the transition section of the simulation body; S5, based on the simulated component body after variable cross-section optimization, clamping sections are set at both ends of the simulated component body to form a blade airframe creep simulation component. The middle part of the simulated component body is the test section, and the clamping sections at both ends of the simulated component body are used for uniaxial tensile loading; Step S5 also includes the following steps: According to the stress characteristics of the turbine blade obtained in step S2, the eccentricity of the clamping section is adjusted so that the stress distribution of the test section of the simulation component is consistent with the stress distribution of the dangerous section of the turbine blade; In the step S5: The clamping section is threaded; After obtaining the blade airfoil creep simulation part, a finite element static analysis model of the blade airfoil creep simulation part is established; a finite element static analysis is performed on the model, and a strength check is performed under the assessment load and environment to ensure that the strength of the clamping section meets the standard.

2. The method for designing a turbine blade airfoil creep simulation component based on consistent cross-sectional stress according to claim 1, characterized in that: The said making the clamping section strength meet the standard means that the maximum stress of the clamping section of the blade body creep simulation part is less than half of the stress of the test section.

3. The method for designing a turbine blade airfoil creep simulation component based on consistent cross-sectional stress according to claim 1, characterized in that: The blade profile parameters in step S2 include: cross-section outer boundary node coordinates, cross-section position, cross-section centroid and centroid coordinates, and cross-section area.

4. The method for designing a turbine blade airfoil creep simulation component based on consistent cross-sectional stress according to claim 1, characterized in that: The stress characteristics in step S2 include the force perpendicular to the dangerous section and the bending moment in the non-vertical direction.

5. The method for designing a turbine blade airfoil creep simulation component based on consistent cross-sectional stress according to claim 1, characterized in that: In step S4, variable cross-section optimization refers to adopting a variable cross-section design to form a smooth and continuous variable cross-section body of the simulation body, and to ensure that the test cross-section of the simulation body is a dangerous cross-section during the test.

6. The method for designing a turbine blade airfoil creep simulation component based on consistent cross-sectional stress according to claim 5, characterized in that: Step S4 also includes: establishing a transition platform of the simulation part with the centroid of the section as the center on the upper and lower sections of the simulation part body that has been optimized for variable section, as a transition section between the simulation part test section and the clamping section.

7. The method for designing a turbine blade airfoil creep simulation component based on consistent cross-sectional stress according to claim 1, characterized in that: In step S2, a simulation part test section consistent with the dangerous section blade is established, the boundary node coordinates of the blade dangerous section are imported into the 3D modeling software UG, and the boundary scattered points of the blade dangerous section are fitted into a closed curve using the curve fitting command to form the test section.

8. The method for designing a turbine blade airfoil creep simulation component based on consistent cross-sectional stress according to claim 5, characterized in that: The specific steps of variable section optimization include: establishing a reference plane on the upper and lower sections of the simulation body, projecting the middle section onto the reference plane, using the scale curve command to enlarge the section to 1.6 times with the center of mass of the section as the scaling center, and then using the curve group command to generate a smooth continuous variable section body through the three sections established above.

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