A hot overspeed pre-rotation test method for improving the life of a gas turbine wheel disc

Abstract

The purpose of this invention is to provide a hot-state overspeed pre-rotation test method for improving the service life of gas turbine disks. 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 rotation, temperature field calibration, and hot-state pre-rotation test. Finally, the validity of the test results is analyzed. If the dimensional requirements are met, the test is stopped; otherwise, the above steps are repeated, and a new test speed is selected. During this process, dynamic balancing standards, installation standards, vibration amplitude standards, and temperature field standards are judged respectively. This invention can effectively improve the service life of the disk and reduce its production cost.

Description

Technical Field

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

[0002] Marine and industrial gas turbines are developing towards higher power and larger size. In order to make the gas turbine have sufficient strength, its rotating disk components are often designed to be thick and heavy, which greatly increases its manufacturing cost. At the same time, its size also occupies a lot of limited space in ships and factories. The disk generally works in a high temperature, high pressure, and high speed environment, and is subjected to the combined effects of centrifugal force, thermal stress and other loads added by itself and the blades. Its destructive energy is huge and can have catastrophic consequences for ships, factories and personal safety. Therefore, it is particularly important to design a method to effectively improve the life of the disk.

[0003] The hot-state overspeed prestressing test technology for wheel disks can improve the stress distribution within the disk. The specific principle is that before service, the disk is rotated at a higher speed than it would be during operation, causing the stress in critical parts of the disk (such as the center hole) to exceed the material's yield stress. This induces plastic deformation in the material. When the high-speed centrifugal force and temperature are released, the plastically deformed parts hinder the recovery of elastic deformation in other parts, thus generating residual compressive stress (negative value) in those areas. After the disk enters service, the stress in its critical parts is the sum of the working stress before pre-rotation (positive value) and the residual compressive stress (negative value), thereby reducing the stress level of the disk after service and increasing its strength reserve and lifespan. Summary of the Invention

[0004] The purpose of this invention is to provide a hot overspeed pre-rotation test method for improving the service life of a gas turbine disk and reducing its production cost.

[0005] The objective of this invention is achieved as follows:

[0006] This invention provides a hot overspeed pre-rotation test method for improving the service life of a gas turbine disk, characterized by comprising the following steps:

[0007] (1) Perform rotor assembly and dynamic balancing;

[0008] (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.

[0009] (3) Install the rotor;

[0010] (4) Perform installation standard judgment. If the circular runout requirement is met, proceed to step (5); otherwise, proceed to step (3).

[0011] (5) Conduct a trial run at room temperature;

[0012] (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.

[0013] (7) Perform temperature field calibration;

[0014] (8) Perform a standard judgment on the temperature field. If the temperature requirement range is met, proceed to step (9); otherwise, repeat step (7).

[0015] (9) Conduct a hot pre-rotation test;

[0016] (10) Analyze the validity of the test results. If the size requirements are met, stop. If not, repeat step (9) and select a new test speed.

[0017] The present invention may also include:

[0018] 1. Step (1) After the rotor is assembled, the diameter of the disc core hole is measured: at least 3 different positions along the axial direction of the disc core hole are measured. At each position, the diameter is measured twice at 90° to each other. These positions are marked on the disc. The average value of the measured dimensions is recorded as Dpp. The temperature when the dimensions are measured is recorded as Ts.

[0019] 2. Step (2) The dynamic balancing standard is that the residual imbalance after dynamic balancing is less than 100 g·mm.

[0020] 3. The installation standard for step (4) is that the circular runout of any circumferential surface of the test piece after installation is less than 0.1 mm.

[0021] 4. The standard for vibration amplitude in step (6) is that the vibration amplitude is less than 70 μm when the test piece reaches the maximum steady-state speed.

[0022] 5. Step (8) The temperature standard is that the absolute value of the difference between the calibrated temperature and the required temperature is less than 10℃.

[0023] 6. Step (9) Hot pre-rotation test speed N H The calculation method is as follows:

[0024]

[0025] and The calculation is as follows:

[0026]

[0027] A, B, and C are coefficients that are related to the disk structure and material properties.

[0028] 7. Step (9) Hot Pre-Rotation Test Requirements: After the wheel reaches the specified temperature, it should be kept at that temperature for at least 1 hour before the test. The wheel should be heated to N. H Rotate at high speed for at least 1 minute;

[0029] After the test, the wheel was cooled down. When the wheel was thermally stable, the temperature was measured. The diameter of the wheel's center hole was measured at the same position and using the same method as in step (1). The average value was recorded as Duse, and the temperature at which the size was measured was recorded as Te.

[0030] 8. The validity analysis of the test results in step (10) is that the difference in aperture growth measured at the center of the disc before and after the rotation test, Duse-Dpp, is between 0.02 and 0.12 mm.

[0031] 9. 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.

[0032] Each diameter measurement should be added to the value Z:

[0033] Z=αD(T s -T e )

[0034] The difference in aperture growth after correction is denoted as:

[0035] Dxz = Duse - Dpp + Z.

[0036] The advantages of this invention are: it can effectively improve the service life of the wheel and reduce the production cost of the wheel. Attached Figure Description

[0037] Figure 1 This is a flowchart of the present invention;

[0038] Figure 2 This is a schematic diagram of a gas turbine disk. Detailed Implementation

[0039] The invention will now be described in more detail with reference to the accompanying drawings:

[0040] Combination Figure 1-2 The present invention provides a hot overspeed pre-rotation test method for improving the service life of a gas turbine disk, the specific steps of which are as follows:

[0041] 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.

[0042] After the rotor is assembled, it needs to be... Figure 2 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.

[0043] 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.

[0044] The standard for dynamic balancing is that the residual imbalance after dynamic balancing should be less than 100 g·mm.

[0045] Step 3: Install the rotor by connecting the rotor test piece to the rotating tester via an intermediate connecting fixture.

[0046] Step 4: Perform an installation standard check. If the circular runout requirement is met, proceed to Step 5; otherwise, proceed to Step 3.

[0047] 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.

[0048] Step 5: Conduct a trial run at room temperature.

[0049] Step 6: Perform vibration amplitude standard judgment. If the vibration standard is met, proceed to step 7. If not, repeat step 1 to rebalance.

[0050] 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.

[0051] Step 7: Perform temperature field calibration.

[0052] Step 8: Perform a standard temperature field judgment. If the temperature meets the requirements, proceed to step 9; otherwise, repeat step 7.

[0053] The temperature standard is that the absolute value of the difference between the calibrated temperature and the required temperature is less than 10℃.

[0054] Step 9: Conduct a hot pre-rotation test. Key parameters for this test include the hot pre-rotation test speed, the holding time before the hot pre-rotation test, the holding time at the hot pre-rotation test speed, and the hot pre-rotation test temperature. Before the temperature reaches the required test temperature, the wheel should be run at a low speed of 100-200 r / min to ensure uniform heating.

[0055] The calculation method for the hot pre-rotation test speed is as follows: Test speed n H For the middle and The minimum speed between.

[0056]

[0057] and The calculation is as follows:

[0058]

[0059] A, B, and C are coefficients that are related to the structure and material properties of the wheel.

[0060] In the formula:

[0061] - Yield limit at t degrees Celsius, 0.02%, in MPa.

[0062] - Yield limit at 0.2% of t degrees Celsius, in MPa.

[0063] - The tensile limit at t degrees Celsius, in MPa.

[0064] Mechanical properties of samples obtained from the region near the center hole of the disc at a temperature of t℃.

[0065] For the hot pre-rotation test, the heat preservation time before the hot pre-rotation test must be at least 1 hour before the test can be carried out, and the load holding time of the hot pre-rotation test speed must be at least 1 minute.

[0066] 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.

[0067] Step 10: Analyze the validity of the test results. If the test results meet the qualification standards, stop the test. If not, repeat step 9 and reselect the test speed for the hot pre-rotation test.

[0068] The test pass criterion is that the difference in aperture growth (Duse-Dpp) measured at the center of the disc before and after the rotation test must be between 0.02 and 0.12 mm.

[0069] 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.

[0070] In this case, the value "Z" should be added to each diameter measurement:

[0071] Z=αD(T s -Te (4)

[0072] In the formula:

[0073] α is the coefficient of linear expansion of the material, measured in °C. -1 .

[0074] D is the nominal diameter of the disc's center hole, in mm.

[0075] Ts is the temperature at which dimensions were measured before the test, in °C.

[0076] Te represents the temperature at which dimensions were measured after the test, in °C.

[0077] The difference in aperture growth after correction is denoted as:

[0078] Dxz=Duse-Dpp+Z (5)

Claims

1. A hot-state overspeed pre-rotation test method for improving the service life of a gas turbine disk, 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 requirement range is met, proceed to step (9); otherwise, repeat step (7). (9) Conduct a hot pre-rotation test; Step (9) Hot pre-rotation test speed N H 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. - Yield strength at 0.02% of t degrees Celsius, in MPa; - Yield strength at 0.2% of t degrees Celsius, in MPa; - Tensile limit at t degrees Celsius, in MPa; Mechanical properties of samples obtained from the region near the center hole of the disc at a temperature of t℃; For the hot pre-rotation test, the heat preservation time before the hot pre-rotation test must be at least 1 hour before the test can be carried out, and the load holding time of the hot pre-rotation test speed must be at least 1 minute. (10) Analyze the validity of the test results. If the size requirements are met, stop. If not, repeat step (9) and select a new test speed.

2. The hot overspeed pre-rotation test method for improving the service life of a gas turbine disk according to claim 1, characterized in that: Step (1) After the rotor is assembled, the diameter of the disc core hole is measured: at least 3 different positions along the axial direction are measured at 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. The average value of the measured dimensions is recorded as Dpp, and the temperature when the dimensions are measured is recorded as Ts.

3. The hot overspeed pre-rotation test method for improving the service life of a gas turbine disk according to claim 1, characterized in that: Step (2) The dynamic balancing standard is that the residual imbalance after dynamic balancing is less than 100 g·mm.

4. The hot overspeed pre-rotation test method for improving the service life of a gas turbine disk according to claim 1, characterized in that: The installation standard for step (4) is that the circular runout of any circumferential surface of the test piece after installation is less than 0.1 mm.

5. The hot overspeed pre-rotation test method for improving the service life of a gas turbine disk according to claim 1, characterized in that: The standard for vibration amplitude in step (6) is that the vibration amplitude is less than 70 μm when the test piece reaches the maximum steady-state speed.

6. The hot overspeed pre-rotation test method for improving the service life of a gas turbine disk according to claim 1, characterized in that: Step (8) The temperature standard is that the absolute value of the difference between the calibrated temperature and the required temperature is less than 10℃.

7. The hot overspeed pre-rotation test method for improving the service life of a gas turbine disk according to claim 1, characterized in that: Step (9) Hot Pre-Rotation Test Requirements: After the wheel reaches the specified temperature, it must be kept at that temperature for at least 1 hour before the test. The wheel should be heated to N. H Rotate at high speed for at least 1 minute; After the test, the wheel was cooled down. When the wheel was thermally stable, the temperature was measured. The diameter of the wheel's center hole was measured at the same position and using the same method as in step (1). The average value was recorded as Duse, and the temperature at which the size was measured was recorded as Te.

8. The hot overspeed pre-rotation test method for improving the service life of a gas turbine disk according to claim 1, characterized in that: The validity analysis of the test results in step (10) shows that the difference in aperture growth measured at the center of the disc before and after the rotation test, Duse-Dpp, is between 0.02 and 0.12 mm.

9. The hot overspeed pre-rotation test method for improving the service life of a gas turbine disk according to claim 1, characterized in that: The difference in aperture growth is considered in the following ways: 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. Each diameter measurement should be added to the value Z: Z=αD(T s -T e ) The difference in aperture growth after correction is denoted as: Dxz = Duse - Dpp + Z.

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