A method for overspeed pre-rotation test of gas turbine disk that combines structural integrity assessment and lifespan improvement

Abstract

The purpose of this invention is to provide a high-speed pre-rotation test method for gas turbine disks that simultaneously assesses structural integrity and improves service life. Belonging to the field of gas turbines, the method includes the following steps: sequentially performing rotor assembly and dynamic balancing, rotor installation, room temperature trial run, temperature field calibration, cold pre-rotation test, and hot pre-rotation test. Then, the validity of the experimental results is analyzed; if the standards are met, the test is stopped; if not, it is repeated until the standards are met. During this process, dynamic balancing standard judgment, installation standard judgment, vibration amplitude standard judgment, and temperature field standard judgment are performed respectively. This invention can effectively improve the service life of the disk, reduce the production cost of the disk, and simultaneously assess the structural integrity of the disk.

Description

Technical Field

[0001] The present invention relates to a gas turbine testing method, specifically a disk testing method. Background Technology

[0002] Gas turbines for marine and industrial applications continue to evolve towards higher power, longer lifespan, and higher reliability. To ensure sufficient strength reserves for core components, the turbine disk is typically designed to be quite thick and heavy. However, this thick disk structure, utilizing high-performance materials, significantly increases manufacturing costs. Furthermore, micro-defects within the disk cannot be detected through conventional non-destructive testing. When the unit starts up under extremely cold conditions, the low-temperature brittleness of the disk material can trigger the propagation of internal defects, leading to disk fracture and potentially catastrophic consequences.

[0003] The overspeed pre-rotation test of a gas turbine disk is an effective test method for improving the fatigue resistance of the disk and verifying its structural integrity, and it has been widely used in the fields of aerospace and industrial gas turbines. Typically, the rotation test can be carried out at three ambient temperatures: hot, cold, and normal, with the pre-rotation test conducted at a specified speed.

[0004] The purposes of hot / room temperature pre-rotation test and cold pre-rotation test are different:

[0005] 1) The goal of the hot / room temperature overspeed pre-rotation test technology for the wheel is to improve the stress distribution within the wheel. Specifically, before service, the wheel is rotated at a higher speed than it would be during operation, causing the stress in critical areas (such as the center hole) to exceed the material's yield stress. This induces plastic deformation. When the high-speed centrifugal force and temperature are released, the plastically deformed areas hinder the recovery of elastic deformation in other areas, resulting in residual compressive stress (negative values) at those locations. After the wheel enters service, the stress in its critical areas is the sum of the working stress before pre-rotation (positive values) and the residual compressive stress (negative values), thus reducing the post-service stress level of the wheel and increasing its strength reserve and lifespan.

[0006] 2) The goal of the cold overspeed prestress test technology for wheel disks is to expand cracks and defects in advance during the overspeed process, so that the wheel disk with large defects will break. If the defects do not lead to failure, the resulting openings can be detected by subsequent non-destructive testing, thereby avoiding possible damage during use.

[0007] For large, heavy gas turbine disks, in order to improve the disk's fatigue life while quickly detecting the disk's structural integrity, the key aspects of pre-rotation testing are how to combine cold and hot rotation testing processes and develop a suitable environmental load spectrum. Summary of the Invention

[0008] The purpose of this invention is to provide a method for overspeed pre-rotation testing of gas turbine disks that can simultaneously and effectively reduce the material cost of the disk and improve its service life, taking into account both structural integrity assessment and life improvement.

[0009] The objective of this invention is achieved as follows:

[0010] This invention provides a method for overspeed pre-rotation testing of a gas turbine disk that simultaneously assesses structural integrity and improves service life, comprising the following steps:

[0011] (1) Perform rotor assembly and dynamic balancing;

[0012] (2) Perform dynamic balance standard judgment. If the unbalance requirement is met, proceed to step (3). If not, repeat step (1) to perform dynamic balance again.

[0013] (3) Install the rotor;

[0014] (4) Perform installation standard judgment. If the circular runout requirement is met, proceed to step (5); otherwise, proceed to step (3).

[0015] (5) Conduct a trial run at room temperature;

[0016] (6) Perform vibration amplitude standard judgment. If the vibration standard is met, proceed to step (7). If not, repeat step (1) to rebalance.

[0017] (7) Perform temperature field calibration;

[0018] (8) Perform a standard judgment on the temperature field. If the temperature field meets the requirements, proceed to step (9); otherwise, repeat step (7).

[0019] (9) Conduct a cold pre-rotation test;

[0020] (10) Conduct a hot pre-rotation test;

[0021] (11) Analyze the validity of the test results. If the test results meet the qualification standards, stop; otherwise, repeat step (9).

[0022] The present invention may also include:

[0023] 1. After the rotor is assembled in step (1), the diameter of the disc core hole is measured: at least 3 different positions are measured along the axial direction of the disc core hole, and the diameter is measured twice at 90° perpendicular to each other at each position. These positions are marked on the disc, and the average value of the measured size is recorded as Dpp; and the temperature when the size is measured is recorded as Ts.

[0024] 2. The dynamic balancing standard for step (2) is: the residual imbalance after dynamic balancing is less than 100 g·mm.

[0025] 3. The installation standard for step (4) is: the circular runout of any circumferential surface of the test piece after installation is less than 0.1 mm.

[0026] 4. The vibration amplitude standard in step (6) is: when the test piece reaches the maximum steady-state speed, its vibration amplitude is less than 70μm.

[0027] 5. The temperature standard for step (8) is: the absolute value of the difference between the calibrated temperature and the required temperature is less than 10℃.

[0028] 6. The calculation method for the cold pre-rotation test speed n2 in step (9) is as follows:

[0029]

[0030] Where K is a coefficient, which is related to the disk structure and material properties.

[0031] 7. The heat preservation time t1 before the cold pre-rotation test shall be at least 3 hours, and the rotation speed t2 of the cold pre-rotation test shall be at least 1 minute.

[0032] 8. The calculation method for the hot pre-rotation test speed n3 in step (10) is as follows:

[0033]

[0034] and The calculation is as follows:

[0035]

[0036] A, B, and C are coefficients that are related to the disk structure and material properties.

[0037] 9. The heat preservation time t3 before the hot pre-rotation test shall be at least 1 hour, and the rotation speed t4 of the hot pre-rotation test shall be at least 1 minute.

[0038] 10. If the material used for the wheel does not exhibit embrittlement within the operating temperature range, choose a room temperature pre-rotation test instead of a hot pre-rotation test, or choose a hot pre-rotation test.

[0039] 11. The calculation method for the rotational speed n3 in the room temperature pre-rotation test is as follows:

[0040]

[0041] and The calculation is as follows:

[0042]

[0043]

[0044] K1 and K2 are coefficients that are related to the disk structure and material properties.

[0045] 12. After the pre-rotation test, the wheel is cooled down. After the wheel is thermally stable, the temperature is measured. The diameter of the wheel's center hole is measured at the same position and using the same method as in step (1). The average value is recorded as Duse, and the temperature at which the size is measured is recorded as Te.

[0046] 13. The validity analysis of the test results in step (12) includes two parts: size detection and crack detection.

[0047] 14. Dimensional inspection refers to the difference in aperture growth (Duse-Dpp) measured at the center of the disc before and after the rotation test. This difference must be between 0.02 and 0.12 mm.

[0048] 15. Crack detection involves performing non-destructive testing on all surfaces of the wheel after the pre-rotation test. If no cracks are found, the wheel meets the structural integrity requirements; if cracks are found, the wheel is scrapped.

[0049] 16. The difference in aperture growth should consider the following factors: If the temperature Te when measuring the size after the test differs from the temperature Ts when measuring the size before the rotation test by more than ±5℃, the thermal expansion of the wheel material should be considered to correct the diameter measurement reading. In this case, the value Z should be added to each diameter measurement:

[0050] Z=αD(T s -T e )

[0051] The difference in aperture growth after correction is denoted as:

[0052] Dxz = Duse - Dpp + Z.

[0053] This invention provides a method for overspeed pre-rotation testing of a gas turbine disk that simultaneously assesses structural integrity and improves service life, characterized by the following steps:

[0054] (1) Perform rotor assembly and dynamic balancing;

[0055] (2) Perform dynamic balance standard judgment. If the unbalance requirement is met, proceed to step (3). If not, repeat step (1) to perform dynamic balance again.

[0056] (3) Install the rotor;

[0057] (4) Perform installation standard judgment. If the circular runout requirement is met, proceed to step (5); otherwise, proceed to step (3).

[0058] (5) Conduct a trial run at room temperature;

[0059] (6) Perform vibration amplitude standard judgment. If the vibration standard is met, proceed to step (7). If not, repeat step (1) to rebalance.

[0060] (7) Perform temperature field calibration;

[0061] (8) Perform a standard judgment on the temperature field. If the temperature field meets the requirements, proceed to step (9); otherwise, repeat step (7).

[0062] (9) Conduct a hot pre-rotation test;

[0063] (10) Conduct a cold pre-rotation test;

[0064] (11) Analyze the validity of the test results. If the test results meet the qualification standards, stop; otherwise, repeat step (9).

[0065] The advantages of this invention are: it can effectively improve the service life of the wheel, reduce the production cost of the wheel, and at the same time complete the assessment of the structural integrity of the wheel. Attached Figure Description

[0066] Figure 1 This is a flowchart of the present invention;

[0067] Figure 2 Diagram of gas turbine disk overspeed pre-rotation test;

[0068] Figure 3 This is a schematic diagram of a gas turbine disk.

[0069] In the figure: n1 is the low-speed operation during the heating and cooling process, n2 is the cold pre-rotation test speed, n3 is the hot pre-rotation test speed, T1 is the cold pre-rotation test temperature, T2 is the hot pre-rotation test temperature, t1 is the holding time before the cold pre-rotation test, t2 is the holding time of the cold pre-rotation test speed n2, t3 is the holding time before the hot pre-rotation test, and t4 is the holding time of the hot pre-rotation test speed n3. Detailed Implementation

[0070] The invention will now be described in more detail with reference to the accompanying drawings:

[0071] Combination Figure 1-3 The present invention provides a method for overspeed pre-rotation testing of a gas turbine disk that combines structural integrity assessment with improved service life, comprising the following steps:

[0072] Step 1: Perform rotor assembly and dynamic balancing, including assembling and dynamically balancing the test piece with the transfer plate, simulated blades and other test components.

[0073] After the rotor is assembled, it needs to be... Figure 3 The diameter of the disc center hole is measured by measuring at least three different locations along the axial direction. At each location, two diameter measurements must be taken at mutually perpendicular 90° angles, and these locations must be marked on the disc. The average of the measured dimensions is recorded as Dpp; the temperature during the measurement is also recorded as Ts.

[0074] Step 2: Perform dynamic balance standard judgment. If the unbalance requirement is met, proceed to Step 3. If not, repeat Step 1 to perform dynamic balance again.

[0075] The standard for dynamic balancing is that the residual imbalance after dynamic balancing should be less than 100 g·mm.

[0076] Step 3: Install the rotor by connecting the rotor test piece to the rotating tester via an intermediate connecting fixture.

[0077] Step 4: Perform an installation standard check. If the circular runout requirement is met, proceed to Step 5; otherwise, proceed to Step 3.

[0078] The installation standard is that the circular runout of any circumferential surface of the test piece after installation should be less than 0.1 mm.

[0079] Step 5: Conduct a trial run at room temperature.

[0080] Step 6: Perform vibration amplitude standard judgment. If the vibration standard is met, proceed to step 7. If not, repeat step 1 to rebalance.

[0081] The standard for vibration amplitude is that the vibration amplitude is less than 70 μm when the test piece reaches its maximum steady-state speed.

[0082] Step 7: Perform temperature field calibration.

[0083] Step 8: Perform a standard temperature field judgment. If the temperature field meets the requirements, proceed to step 9; otherwise, repeat step 7.

[0084] The temperature field standard is that the absolute value of the difference between the calibrated temperature and the required temperature is less than 10℃.

[0085] Step 9: Conduct a cold pre-rotation test. The key parameters for this test include n2, t1, t2, and T1. Before the temperature reaches the required test temperature, the wheel should be rotated at a low speed of n1 to ensure uniform cooling.

[0086] The calculation method for the cold pre-rotation test speed n2 is as follows:

[0087]

[0088] Where K is a coefficient, which is related to the disk structure and material properties.

[0089] In the formula:

[0090] - Yield strength of 0.2% at 20 degrees Celsius, in MPa.

[0091] Mechanical properties of samples taken from the region near the center hole of the disc at 20°C.

[0092] For the cold pre-rotation test, the heat preservation time t1 before the cold pre-rotation test is at least 3 hours, and the rotation speed t2 of the cold pre-rotation test is at least 1 minute.

[0093] During the heating and cooling process, the low-speed operating speed n1 is generally taken as 100 to 200 rpm.

[0094] Step 10: Conduct a hot pre-rotation test. The key parameters for this test include n3, t3, t4, and T2. Before the required test temperature is reached, the wheel should be rotated at a low speed of n1 to ensure uniform heating.

[0095] The calculation method for the hot pre-rotation test speed n3 is as follows: the test speed n3 is between... and The minimum speed between.

[0096]

[0097] and The calculation is as follows:

[0098]

[0099] A, B, and C are coefficients that are related to the structure and material properties of the wheel.

[0100] In the formula:

[0101] - Yield strength at 0.02% of T2 degrees Celsius, in MPa.

[0102] - Yield limit of 0.2% at T2 degrees Celsius, in MPa.

[0103] - The tensile limit at T2 degrees Celsius, in MPa.

[0104] Mechanical properties of samples obtained from the region near the center hole of the disc at a temperature of T2℃.

[0105] If the material used for the wheel does not exhibit embrittlement within its operating temperature range, a room-temperature pre-rotation test can be used instead of a hot-state pre-rotation test. The calculation method for the room-temperature pre-rotation test speed is as follows: the test speed n3 is between... and The minimum speed between.

[0106]

[0107] and The calculation is as follows:

[0108]

[0109] K1 and K2 are coefficients that are related to the structure and material properties of the wheel.

[0110] In the formula:

[0111] - Yield strength of 0.2% at 20 degrees Celsius, in MPa.

[0112] - Tensile limit at 20 degrees Celsius, in MPa.

[0113] Mechanical properties of samples taken from the region near the center hole of the disc at 20°C.

[0114] For the hot pre-rotation test, the heat preservation time t1 before the hot pre-rotation test is at least 1 hour, and the rotation speed t2 of the hot pre-rotation test is at least 1 minute.

[0115] After the experiment, the wheel was cooled down. Once the wheel was thermally stable, the temperature was measured. The diameter of the wheel's center hole was measured at the same location and using the same method as in step 1. The average value was recorded as Duse, and the temperature at which the dimension was measured was recorded as Te.

[0116] Step 11: Conduct a validity analysis of the test results (including two parts: dimensional inspection and crack inspection). If the test meets the qualification criteria, stop the test. If not, double-check the correct application of material data and formulas, select a new test speed, and repeat step 9 to conduct the test.

[0117] The dimensional inspection is performed before and after the rotation test. The difference in aperture growth (Duse-Dpp) measured at the center of the disc must be between 0.02 and 0.12 mm.

[0118] If the temperature Te when measuring the dimensions after the test differs from the temperature Ts when measuring the dimensions before the rotation test by more than ±5℃, it is necessary to consider the thermal expansion of the wheel material to correct the diameter measurement reading.

[0119] In this case, the value "Z" should be added to each diameter measurement:

[0120] Z=αD(T s -T e (8)

[0121] In the formula:

[0122] α is the coefficient of linear expansion of the material, measured in °C. -1 .

[0123] D is the nominal diameter of the disc's center hole, in mm.

[0124] Ts is the temperature at which dimensions were measured before the test, in °C.

[0125] Te represents the temperature at which dimensions were measured after the test, in °C.

[0126] The difference in aperture growth after correction is denoted as:

[0127] Dxz=Duse-Dpp+Z (9)

[0128] Crack detection involves performing non-destructive testing on all surfaces of the wheel after a pre-rotation test. If no cracks are found, the wheel meets the structural integrity requirements; otherwise, the wheel is scrapped.

[0129] The order of pre-rotation tests is not fixed. The same wheel can be subjected to cold pre-rotation test first and then hot pre-rotation test. Alternatively, only one type of pre-rotation test can be performed as needed.

Claims

1. A method of super-speed pre-rotation test for a gas turbine disk, which is a test method for both structural integrity examination and life improvement, characterized in that: Includes the following steps: ​ (1) Perform rotor assembly and dynamic balancing; (2) Perform dynamic balance standard judgment. If the unbalance requirement is met, proceed to step (3). If not, repeat step (1) to perform dynamic balance again. (3) Install the rotor; (4) Perform installation standard judgment. If the circular runout requirement is met, proceed to step (5); otherwise, proceed to step (3). (5) Conduct a trial run at room temperature; (6) Perform vibration amplitude standard judgment. If the vibration standard is met, proceed to step (7). If not, repeat step (1) to perform dynamic balancing again. (7) Perform temperature field calibration; (8) Perform a standard judgment on the temperature field. If the temperature field meets the requirements, proceed to step (9); otherwise, repeat step (7). (9) Conduct a cold pre-rotation test; The calculation method for the cold pre-rotation test speed n2 is as follows: Where K is a coefficient, which is related to the disk structure and material properties; - Yield strength of 0.2% at 20 degrees Celsius, in MPa; Mechanical properties of samples obtained from the region near the center hole of the disc at 20°C; For the cold pre-rotation test, the heat preservation time t1 before the cold pre-rotation test is at least 3 hours, and the rotation speed t2 of the cold pre-rotation test is at least 1 minute. (10) Conduct a hot pre-rotation test; (11) Analyze the validity of the test results. If the test results meet the qualification standards, stop; otherwise, repeat step (9).

2. The overspeed pre-rotation test method for a gas turbine disk that combines structural integrity assessment and lifespan improvement according to claim 1, characterized in that: After the rotor is assembled in step (1), the diameter of the disc core hole is measured: at least three different positions are measured along the axial direction of the disc core hole, and the diameter is measured twice at 90° perpendicular to each other at each position. These positions are marked on the disc, and the average value of the measured dimensions is recorded as Dpp. The temperature at the time of measurement is recorded as Ts.

3. The overspeed pre-rotation test method for a gas turbine disk that combines structural integrity assessment and lifespan improvement according to claim 1, characterized in that: The dynamic balancing standard for step (2) is: the residual imbalance after dynamic balancing is less than 100 g•mm.

4. The overspeed pre-rotation test method for a gas turbine disk that combines structural integrity assessment and lifespan improvement according to claim 1, characterized in that: The installation standard for step (4) is: the circular runout of any circumferential surface of the test piece after installation is less than 0.1 mm.

5. The overspeed pre-rotation test method for a gas turbine disk that combines structural integrity assessment and lifespan improvement according to claim 1, characterized in that: The vibration amplitude standard for step (6) is: when the test piece reaches the maximum steady-state speed, its vibration amplitude is less than 70 μm.

6. The overspeed pre-rotation test method for a gas turbine disk that combines structural integrity assessment and lifespan improvement according to claim 1, characterized in that: The temperature standard for step (8) is: the absolute value of the difference between the calibrated temperature and the required temperature is less than 10℃.

7. The overspeed pre-rotation test method for a gas turbine disk that combines structural integrity assessment and lifespan improvement according to claim 1, characterized in that: The heat preservation time t1 before the cold pre-rotation test is at least 3 hours, and the rotation speed t2 of the cold pre-rotation test is at least 1 minute.

8. The overspeed pre-rotation test method for a gas turbine disk that combines structural integrity assessment and lifespan improvement according to claim 1, characterized in that: The hot pre-rotation test speed in step (10) The calculation method is as follows: and The calculation is as follows: A, B, and C are coefficients that are related to the disk structure and material properties.

9. The overspeed pre-rotation test method for a gas turbine disk that combines structural integrity assessment and lifespan improvement according to claim 1, characterized in that: The heat preservation time t3 before the hot pre-rotation test is at least 1 hour, and the rotation speed t4 of the hot pre-rotation test is at least 1 minute.

10. The overspeed pre-rotation test method for a gas turbine disk that combines structural integrity assessment and lifespan improvement according to claim 1, characterized in that: If the material used for the wheel does not exhibit embrittlement within the operating temperature range, choose a room temperature pre-rotation test instead of a hot pre-rotation test, or choose a hot pre-rotation test.

11. The overspeed pre-rotation test method for a gas turbine disk that combines structural integrity assessment and lifespan improvement according to claim 10, characterized in that: Room temperature pre-rotation test, its rotation speed The calculation method is as follows: and The calculation is as follows: K1 and K2 are coefficients that are related to the disk structure and material properties.

12. The overspeed pre-rotation test method for a gas turbine disk that combines structural integrity assessment and lifespan improvement according to claim 1, characterized in that: After the pre-rotation test, the wheel is cooled down. After the wheel is thermally stable, the temperature is measured. The diameter of the wheel's center hole is measured at the same position and using the same method as in step (1). The average value is recorded as Duse, and the temperature at which the size is measured is recorded as Te.

13. The overspeed pre-rotation test method for a gas turbine disk that combines structural integrity assessment and lifespan improvement according to claim 1, characterized in that: The validity analysis of the test results in step (12) consists of two parts: size detection and crack detection.

14. The overspeed pre-rotation test method for a gas turbine disk that combines structural integrity assessment and lifespan improvement according to claim 13, characterized in that: The dimensional inspection is performed before and after the rotation test at the center of the disc, and the difference in aperture growth (Duse-Dpp) must be between 0.02 and 0.12 mm.

15. The overspeed pre-rotation test method for a gas turbine disk that combines structural integrity assessment and lifespan improvement according to claim 13, characterized in that: Crack detection involves performing non-destructive testing on all surfaces of the wheel after a pre-rotation test. If no cracks are found, the wheel meets the structural integrity requirements; otherwise, the wheel is scrapped.

16. The overspeed pre-rotation test method for a gas turbine disk that combines structural integrity assessment and lifespan improvement according to claim 14, characterized in that: The difference in aperture growth is considered in the following way: If the temperature Te at the time of measurement after the test differs from the temperature Ts at the time of measurement before the rotation test by more than ±5℃, the thermal expansion of the wheel material is considered to correct the diameter measurement reading. In this case, the value Z is added to each diameter measurement. The difference in aperture growth after correction is denoted as: Dxz = Duse - Dpp + Z.

17. A method for overspeed pre-rotation testing of a gas turbine disk that simultaneously assesses structural integrity and improves service life, characterized by: Includes the following steps: (1) Perform rotor assembly and dynamic balancing; (2) Perform dynamic balance standard judgment. If the unbalance requirement is met, proceed to step (3). If not, repeat step (1) to perform dynamic balance again. (3) Install the rotor; (4) Perform installation standard judgment. If the circular runout requirement is met, proceed to step (5); otherwise, proceed to step (3). (5) Conduct a trial run at room temperature; (6) Perform vibration amplitude standard judgment. If the vibration standard is met, proceed to step (7). If not, repeat step (1) to perform dynamic balancing again. (7) Perform temperature field calibration; (8) Perform a standard judgment on the temperature field. If the temperature field meets the requirements, proceed to step (9); otherwise, repeat step (7). (9) Conduct a hot pre-rotation test; (10) Conduct a cold pre-rotation test; The calculation method for the cold pre-rotation test speed n2 is as follows: Where K is a coefficient, which is related to the disk structure and material properties; - Yield strength of 0.2% at 20 degrees Celsius, in MPa; Mechanical properties of samples obtained from the region near the center hole of the disc at 20°C; For the cold pre-rotation test, the heat preservation time t1 before the cold pre-rotation test is at least 3 hours, and the rotation speed t2 of the cold pre-rotation test is at least 1 minute. (11) Analyze the validity of the test results. If the test results meet the qualification standards, stop; otherwise, repeat step (9).

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