Overspeed pre-rotation test method for gas turbine wheel disc with consideration of structural integrity examination and service life prolonging

Abstract

The invention aims to provide a gas turbine wheel disc overspeed pre-rotation test method considering structural integrity examination and service life prolonging, and belongs to the field of gas turbines, and the method comprises the following steps: sequentially carrying out rotor assembly and dynamic balance, rotor installation, normal temperature test rotation, temperature field calibration, cold state pre-rotation test and hot state pre-rotation test; and then carrying out experimental result validity analysis, stopping if a standard is met, repeating until the standard is not met, and respectively carrying out dynamic balance standard judgment, installation standard judgment, vibration amplitude standard judgment, temperature field standard judgment and the like in the period. The service life of the wheel disc can be effectively prolonged, the production cost of the wheel disc is reduced, and meanwhile, the structural integrity of the wheel disc is checked.

Description

Technical Field

[0001] The present invention relates to a gas turbine testing method, in particular to a wheel disc testing method. Background Art

[0002] Marine and industrial gas turbines continue to develop in the direction of high power, long life, and high reliability. In order to ensure that the core components of gas turbines have sufficient strength reserves, the rotating disc is usually designed to be thicker. The thick disc structure made of high-performance materials will first significantly increase the production and manufacturing costs; on the other hand, the micro defects inside the disc cannot be found through ordinary non-destructive testing. When the unit is started under extremely cold conditions, the low-temperature brittleness of the disc material will cause the internal defects to expand, leading to disc rupture, and then causing catastrophic consequences.

[0003] The disc overspeed pre-rotation test is an effective test method to improve the disc fatigue resistance and verify the structural integrity. It has been widely used in the fields of aviation and industrial gas turbines. Usually, the rotation test can be carried out at three ambient temperatures: hot, cold and room temperature. The pre-rotation test is carried out at the specified speed.

[0004] The purposes of the hot / normal temperature pre-spin test and the cold pre-spin test are different:

[0005] 1) The goal of the hot / normal temperature overspeed pre-rotation test technology of the wheel is to improve the stress distribution inside the wheel. The specific principle is to rotate the wheel at a higher speed than the speed during service before it is put into service, so that the stress in the key parts of the wheel (such as the center hole of the wheel) exceeds the yield stress of the material, and the material undergoes plastic deformation. When the high-speed centrifugal force and temperature are unloaded, the plastically deformed part hinders the recovery of the elastic deformation of other parts, and residual compressive stress (negative value) is generated in this part. After the wheel is put into service, the stress in its key parts is the stress level of the working stress of the unpre-rotated wheel (positive value) superimposed on the residual compressive stress (negative value), thereby reducing the stress level of the wheel after service and improving the strength reserve and life of the wheel.

[0006] 2) The goal of the wheel cold overspeed prestressing test technology is to expand the crack defects in advance during the overspeed process to cause the wheel with large defects to rupture; if the defects do not cause damage, the resulting opening can be detected by subsequent non-destructive testing, thereby avoiding possible damage during use.

[0007] For large-sized and heavy gas turbine impellers, in order to improve the fatigue life of the impeller and quickly detect the structural integrity of the impeller, how to match the cold spinning test and hot spinning test processes and develop a suitable environmental load spectrum are key links in the pre-rotation test. Summary of the invention

[0008] The object of the present invention is to provide an overspeed pre-rotation test method for a gas turbine wheel that can simultaneously and effectively reduce the material cost of the wheel and increase the service life of the wheel, taking into account both structural integrity assessment and life improvement.

[0009] The object of the present invention is achieved in that:

[0010] The present invention provides an overspeed pre-rotation test method for a gas turbine wheel disc that takes into account both structural integrity assessment and life extension, comprising the following steps:

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

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

[0013] (3) Install the rotor;

[0014] (4) Determine the installation standard. If the circular runout requirement is met, proceed to step (5); if not, proceed to step (3);

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

[0016] (6) Determine the vibration amplitude standard. If the vibration standard is met, proceed to step (7). If not, repeat step (1) to re-dynamically balance.

[0017] (7) Perform temperature field calibration;

[0018] (8) Perform temperature field standard judgment. If the temperature field meets the required range, proceed to step (9); if not, repeat step (7);

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

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

[0021] (11) Analyze the validity of the test results. If the test results meet the requirements of the test qualification standards, stop the test. If not, repeat step (9).

[0022] The present invention may also include:

[0023] 1. After the rotor of step (1) is assembled, the diameter of the center hole of the disk is measured: no less than 3 different positions of the center hole are measured along the axial direction, and the diameter of each position is measured twice at 90° perpendicular to each other. These positions are marked on the wheel disc, and the average value of the measured dimensions is recorded as Dpp; and the temperature when the dimensions are measured is recorded as Ts.

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

[0025] 3. The installation standard of 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 of step (6) is: when the test piece reaches the maximum steady-state speed, its vibration amplitude is less than 70 μm.

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

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

[0029]

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

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

[0032] 8. Step (10) hot pre-rotation test speed n 3 The calculation method is:

[0033]

[0034] and The calculation is as follows:

[0035]

[0036] Among them, A, B, and C are coefficients, which are related to the wheel structure and material properties.

[0037] 9. The holding time t3 before the hot pre-rotation test shall be at least 1h, and the hot pre-rotation test speed t4 shall be at least 1min.

[0038] 10. If the material used for the wheel does not show brittleness within the operating temperature range, select the normal temperature pre-rotation test instead of the hot pre-rotation test or select the hot pre-rotation test.

[0039] 11. Pre-rotation test at room temperature, the speed n 3 The calculation method is:

[0040]

[0041] and The calculation is as follows:

[0042]

[0043]

[0044] Among them, K1 and K2 are coefficients, which are related to the wheel structure and material properties.

[0045] 12. After the pre-rotation test, the wheel is cooled down. When the wheel is thermally stable, the temperature is measured. The diameter of the center hole of the wheel is measured by the same method at the same position as 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, one is size detection and the other is crack detection.

[0047] 14. The size test is that the difference in the aperture growth Duse-Dpp measured at the center of the wheel before and after the rotation test must be between 0.02-0.12mm.

[0048] 15. After the pre-rotation test, non-destructive testing is performed on all surfaces of the wheel disc. If no cracks are found, the wheel disc meets the structural integrity inspection. If cracks are found, the wheel disc will be scrapped.

[0049] 16. The difference in hole diameter growth takes into account the following factors: If the temperature Te when the size is measured after the test differs from the temperature Ts when the size is measured before the rotation test by more than ±5°C, the thermal expansion of the wheel material is taken into account to correct the diameter measurement reading. In this case, the value Z is added to each diameter measurement:

[0050] Z = αD(T s -T e )

[0051] The difference in the corrected aperture growth is recorded as:

[0052] Dxz=Duse-Dpp+Z.

[0053] The present invention provides an overspeed pre-rotation test method for a gas turbine wheel disc that takes into account both structural integrity assessment and life extension, and is characterized by comprising the following steps:

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

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

[0056] (3) Install the rotor;

[0057] (4) Determine the installation standard. If the circular runout requirement is met, proceed to step (5); if not, proceed to step (3);

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

[0059] (6) Determine the vibration amplitude standard. If the vibration standard is met, proceed to step (7). If not, repeat step (1) to re-dynamically balance.

[0060] (7) Perform temperature field calibration;

[0061] (8) Perform temperature field standard judgment. If the temperature field meets the required range, proceed to step (9); if not, repeat step (7);

[0062] (9) Conducting 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 requirements of the test qualification standards, stop the test. If not, repeat step (9).

[0065] The advantages of the present invention are that the present invention can effectively increase the service life of the wheel disc, reduce the production cost of the wheel disc, and simultaneously complete the assessment of the structural integrity of the wheel disc. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 is a flow chart of the present invention;

[0067] Figure 2 It is the gas turbine wheel overspeed pre-rotation test map;

[0068] Figure 3 Schematic diagram of a gas turbine disc.

[0069] In the figure: n1 is the low-speed running speed 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 DESCRIPTION

[0070] The present invention is described in more detail below with reference to the accompanying drawings:

[0071] Combination Figure 1-3 The present invention provides an overspeed pre-rotation test method for a gas turbine wheel disc that takes into account both structural integrity assessment and life extension, comprising the following steps:

[0072] Step 1: Assemble and dynamically balance the rotor, including assembling and dynamically balancing the test piece with the adapter plate, simulated blades and other accompanying test pieces.

[0073] After the rotor is assembled, Figure 3 The diameter of the center hole of the wheel is measured by measuring at least 3 different positions along the axial direction of the center hole. Each position needs to be measured twice at 90° perpendicular to each other, and these positions must be marked on the wheel. The average value of the measured multiple dimensions is recorded as Dpp; and the temperature when the dimension is measured is recorded as Ts.

[0074] Step 2: Determine the dynamic balance standard. If the unbalance requirement is met, proceed to step 3. If not, repeat step 1 to re-balance.

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

[0076] Step 3: Install the rotor and connect the rotor test piece to the rotation tester through the intermediate connecting fixture.

[0077] Step 4: Determine the installation standard. If the circular runout requirement is met, proceed to step 5. If not, proceed to step 3.

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

[0079] Step 5: Perform a test run at room temperature.

[0080] Step 6: Determine the vibration amplitude standard. If it meets the vibration standard, proceed to step 7. If it does not meet the standard, repeat step 1 to re-balance.

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

[0082] Step 7: Perform temperature field calibration.

[0083] Step 8: Make a temperature field standard judgment. If the temperature field meets the required range, proceed to step 9. If not, repeat step 7.

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

[0085] Step 9: Carry out a cold pre-rotation test, the key parameters of which include n2, t1, t2 and T1. Before the temperature reaches the test temperature, it must be run at a low speed of n1 to ensure that the wheel is cooled evenly.

[0086] Cold pre-rotation test speed n 2 The calculation method is:

[0087]

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

[0089] Where:

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

[0091] The mechanical properties of the samples collected from the area near the center hole of the disk at a temperature of 20°C were used.

[0092] Cold pre-rotation test: the holding time t1 before the cold pre-rotation test is at least 3h, and the cold pre-rotation test speed t2 is at least 1min.

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

[0094] Step 10: Conduct a hot pre-rotation test, the key parameters of which include n3, t3, t4 and T2. Before the temperature reaches the test temperature, it must be run at a low speed of n1 to ensure that the wheel is heated evenly.

[0095] The calculation method of hot pre-rotation test speed n3 is: test speed n 3 For between and The minimum speed between.

[0096]

[0097] and The calculation is as follows:

[0098]

[0099] Among them, A, B, and C are coefficients, which are related to the wheel structure and material properties.

[0100] Where:

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

[0102] - 0.2% yield strength at T2 degrees Celsius, in MPa.

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

[0104] The mechanical properties of the specimens collected from the area near the center hole of the disk at a temperature of T2°C were used.

[0105] If the material used for the wheel does not become brittle within the operating temperature range, a normal temperature pre-rotation test can be used instead of a hot pre-rotation test. The calculation method for the normal temperature pre-rotation test speed is: test speed n 3 For between and The minimum speed between.

[0106]

[0107] and The calculation is as follows:

[0108]

[0109] Among them, K1 and K2 are coefficients, which are related to the wheel structure and material properties.

[0110] Where:

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

[0112] -The tensile strength at 20 degrees Celsius, in MPa.

[0113] The mechanical properties of the samples collected from the area near the center hole of the disk at a temperature of 20°C were used.

[0114] Hot pre-rotation test: the holding time t1 before the hot pre-rotation test shall be at least 1h, and the hot pre-rotation test speed t2 shall be at least 1min.

[0115] After the test, the wheel is cooled down. When the wheel is thermally stable, the temperature is measured. The diameter of the center hole of the wheel is measured by the same method at the same position as step 1. The average value is recorded as Duse, and the temperature when the size is measured is recorded as Te.

[0116] Step 11: Perform validity analysis on the test results (including two parts, one for size detection and the other for crack detection). If the test meets the requirements of the qualified standards, stop. If not, double-check the correct application of material data and formulas, re-select the test speed and repeat step 9 to conduct the test.

[0117] The size test is that the difference in the hole diameter growth (Duse-Dpp) measured at the center of the wheel disc before and after the rotation test must be between 0.02-0.12mm.

[0118] If the temperature Te at which the dimensions are measured after the test differs by more than ±5°C from the temperature Ts at which the dimensions are measured before the rotation test, it is necessary to correct the diameter measurement reading to take into account the thermal expansion of the disc material.

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

[0120] Z = αD(T s -T e ) (8)

[0121] Where:

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

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

[0124] Ts is the temperature when the dimensions are measured before the test, in °C.

[0125] Te is the temperature when the dimensions are measured after the test, in °C.

[0126] The difference in the corrected aperture growth is recorded as:

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

[0128] Crack detection is a non-destructive test of all surfaces of the wheel disc after the pre-rotation test. If no cracks are found, the wheel disc meets the structural integrity inspection. If cracks are found, the wheel disc will be scrapped.

[0129] The order of pre-rotation tests is not fixed. The same wheel can be subjected to a cold pre-rotation test first and then a hot pre-rotation test, or only one pre-rotation test can be carried out according to actual needs.

Claims

1. An overspeed pre-rotation test method for a gas turbine wheel disc that takes into account both structural integrity assessment and life extension, characterized by: The steps include: (1) Perform rotor assembly and dynamic balancing; (2) Determine the dynamic balance standard. If the unbalance requirement is met, proceed to step (3). If not, repeat step (1) to perform dynamic balancing again. (3) Install the rotor; (4) Determine the installation standard. If the circular runout requirement is met, proceed to step (5); if not, proceed to step (3); (5) Conduct a test run at room temperature; (6) Determine the vibration amplitude standard. If the vibration standard is met, proceed to step (7). If not, repeat step (1) to re-dynamically balance. (7) Perform temperature field calibration; (8) Perform temperature field standard judgment. If the temperature field meets the required range, proceed to step (9); if not, repeat step (7); (9) Conduct a cold pre-rotation test; (10) Conducting a hot pre-rotation test; (11) Analyze the validity of the test results. If the test results meet the requirements of the test qualification standards, stop the test. If not, repeat step (9).

2. The overspeed pre-rotation test method for a gas turbine disk according to claim 1, which takes into account both structural integrity assessment and life extension, is characterized by: After the rotor is assembled in step (1), the diameter of the center hole of the disk is measured: no less than 3 different positions of the center hole are measured along the axial direction, and the diameter of each position is measured twice at 90° perpendicular to each other. These positions are marked on the wheel disk, and 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 overspeed pre-rotation test method for a gas turbine disk according to claim 1, which takes into account both structural integrity assessment and life extension, is characterized by: The dynamic balancing standard of step (2) is: the residual unbalance after dynamic balancing is less than 100 g·mm.

4. The overspeed pre-rotation test method for a gas turbine disk according to claim 1, which takes into account both structural integrity assessment and life extension, is characterized by: The installation standard of 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 according to claim 1, which takes into account both structural integrity assessment and life extension, is characterized by: The vibration amplitude standard of step (6) is: when the test piece reaches the maximum steady-state rotation speed, its vibration amplitude is less than 70 μm.

6. The overspeed pre-rotation test method for a gas turbine disk according to claim 1, which takes into account both structural integrity assessment and life extension, is characterized by: The temperature standard of step (8) is: the absolute value of the difference between the calibration temperature and the required temperature is less than 10°C.

7. The overspeed pre-rotation test method for a gas turbine disk for both structural integrity assessment and life extension according to claim 1 is characterized by: The calculation method of the cold pre-rotation test speed n2 in step (9) is: Where K is a coefficient, which is related to the wheel structure and material properties.

8. The overspeed pre-rotation test method for a gas turbine disk according to claim 1, which takes into account both structural integrity assessment and life extension, is characterized by: The holding time t1 before the cold pre-rotation test shall be at least 3 hours, and the cold pre-rotation test speed t2 shall be at least 1 minute.

9. The overspeed pre-rotation test method for a gas turbine disk for both structural integrity assessment and life extension according to claim 1 is characterized by: The calculation method of the hot pre-rotation test speed n3 in step (10) is: and The calculation is as follows: Among them, A, B, and C are coefficients, which are related to the wheel structure and material properties.

10. The overspeed pre-rotation test method for a gas turbine disk for both structural integrity assessment and life extension according to claim 1, characterized in that: The holding time t3 before the hot pre-rotation test shall be at least 1 hour, and the hot pre-rotation test speed t4 shall be at least 1 minute.

11. The overspeed pre-rotation test method for a gas turbine disk according to claim 1, which takes into account both structural integrity assessment and life extension, is characterized by: If the material used for the wheel does not show embrittlement within the operating temperature range, select the normal temperature pre-rotation test instead of the hot pre-rotation test or select the hot pre-rotation test.

12. The overspeed pre-rotation test method for a gas turbine disk according to claim 11, which takes into account both structural integrity assessment and life extension, and is characterized by: In the normal temperature pre-rotation test, the speed n3 is calculated as follows: and The calculation is as follows: Among them, K1 and K2 are coefficients, which are related to the wheel structure and material properties.

13. The overspeed pre-rotation test method for a gas turbine disk according to claim 1, which takes into account both structural integrity assessment and life extension, is characterized by: After the pre-rotation test, the wheel is cooled down. When the wheel is thermally stable, the temperature is measured. The diameter of the center hole of the wheel is measured by the same method at the same position as step (1). The average value is recorded as Duse, and the temperature at which the size is measured is recorded as Te.

14. The overspeed pre-rotation test method for a gas turbine disk according to claim 1, which takes into account both structural integrity assessment and life extension, is characterized by: The validity analysis of the test results in step (12) includes two parts, one is size detection and the other is crack detection.

15. The overspeed pre-rotation test method for a gas turbine disk according to claim 14, which takes into account both structural integrity assessment and life extension, is characterized by: The size test is that the difference in hole diameter growth Duse-Dpp measured at the center of the wheel before and after the rotation test must be between 0.02-0.12mm.

16. The overspeed pre-rotation test method for a gas turbine disk according to claim 14, which takes into account both structural integrity assessment and life extension, is characterized by: Crack detection is a non-destructive test of all surfaces of the wheel disc after the pre-rotation test. If no cracks are found, the wheel disc meets the structural integrity inspection. If cracks are found, the wheel disc will be scrapped.

17. The overspeed pre-rotation test method for a gas turbine disk according to claim 15, which takes into account both structural integrity assessment and life extension, is characterized by: The difference in hole diameter growth is taken into account as follows: If the temperature Te at which the dimensions are measured after the test differs from the temperature Ts at which the dimensions are measured before the rotation test by more than ±5°C, the diameter reading is corrected to take into account the thermal expansion of the disc material. In this case, the value Z is added to each diameter measurement: Z=αD(T s -T e ) The difference in the corrected aperture growth is recorded as: Dxz=Duse-Dpp+Z.

18. An overspeed pre-rotation test method for a gas turbine wheel disc that takes into account both structural integrity assessment and life extension, characterized by: The steps include: (1) Perform rotor assembly and dynamic balancing; (2) Determine the dynamic balance standard. If the unbalance requirement is met, proceed to step (3). If not, repeat step (1) to perform dynamic balancing again. (3) Install the rotor; (4) Determine the installation standard. If the circular runout requirement is met, proceed to step (5); if not, proceed to step (3); (5) Conduct a test run at room temperature; (6) Determine the vibration amplitude standard. If the vibration standard is met, proceed to step (7). If not, repeat step (1) to re-dynamically balance. (7) Perform temperature field calibration; (8) Perform temperature field standard judgment. If the temperature field meets the required range, proceed to step (9); if not, repeat step (7); (9) Conducting a hot pre-rotation test; (10) Conducting a cold pre-rotation test; (11) Analyze the validity of the test results. If the test results meet the requirements of the test qualification standards, stop the test. If not, repeat step (9).

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