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

Abstract

The application aims to provide a normal-temperature overspeed pre-rotation test method for improving the service life of a gas turbine disc, belonging to the field of gas turbines, and comprising the following steps: sequentially performing rotor assembly and dynamic balancing, rotor installation, normal-temperature trial rotation, and normal-temperature pre-rotation test, finally performing test result effectiveness analysis, stopping if the test meets the test qualification standard requirement, and repeating the above steps and selecting a test rotation speed again for normal-temperature pre-rotation test if the test does not meet the test qualification standard requirement, during which dynamic balancing standard judgment, installation standard judgment, and vibration amplitude standard judgment are performed respectively. The application can effectively improve the service life of the disc and reduce the production cost of the disc.

Description

TECHNICAL FIELD

[0001] The present application relates to a gas turbine test method, in particular, a wheel disc test method. BACKGROUND

[0002] The ship and industrial gas turbine develop towards higher power and larger size. In order to make the gas turbine have enough strength, the rotating part of the wheel disc is often designed to be thick and heavy, which greatly increases the production cost, and the size also greatly occupies the limited space of the ship and the factory building. The wheel disc generally works in a high temperature, high pressure and high speed working environment, and bears the combined action of centrifugal force, thermal stress and other loads of itself and the blade, and the damage energy is huge, which will have disastrous consequences on the ship, the factory building and personal safety. Therefore, how to design a method to effectively improve the service life of the wheel disc is particularly important.

[0003] Generally, the wheel disc is heated and then subjected to overspeed pre-rotation test, which is more likely to obtain plasticity in the wheel disc core, but the test process is relatively complicated, and the technical level of the test personnel and the test equipment are relatively high. If the material of the wheel disc does not have a brittle phenomenon in the working temperature range, the wheel disc can be directly subjected to overspeed at normal temperature, which also has the effect of improving the stress distribution of the wheel disc as the thermal state overspeed pre-rotation test. SUMMARY

[0004] The purpose of the present application is to provide a normal temperature overspeed pre-rotation test method for improving the service life of a gas turbine wheel disc, which can effectively improve the service life of the wheel disc and reduce the production cost of the wheel disc.

[0005] The purpose of the present application is achieved in the following way:

[0006] The normal temperature overspeed pre-rotation test method for improving the service life of a gas turbine wheel disc, characterized by comprising the following steps:

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

[0008] (2) performing dynamic balancing standard judgment, if the unbalance requirement is met, step (3) is performed, otherwise, step (1) is repeated to perform re-dynamic balancing;

[0009] (3) performing rotor installation;

[0010] (4) performing installation standard judgment, if the round run-out requirement is met, step (5) is performed, otherwise, step (3) is performed;

[0011] (5) performing normal temperature test rotation;

[0012] (6) performing vibration amplitude standard judgment, if the vibration standard is met, step (7) is performed, otherwise, step (1) is repeated to perform re-dynamic balancing;

[0013] (7) Perform normal temperature pre-rotation test;

[0014] (8) Perform test result validity analysis, if the test qualified standard requirements are met, stop, if not, repeat step (7), select test speed again to perform normal temperature pre-rotation test.

[0015] The application can also include:

[0016] 1. After the rotor assembly in step (1) is completed, the diameter of the disc core hole is measured: along the axial direction, at least 3 different positions in the disc core hole are measured, twice diameter measurement is performed at each position at 90° perpendicular to each other, and the positions are marked on the wheel disc, the measured size is averaged and recorded as Dpp, and the temperature when the size is measured is recorded as Ts.

[0017] 2. The dynamic balance standard in step (2) is that the residual unbalance after dynamic balance is less than 100g·mm.

[0018] 3. The installation standard in step (4) is that the circular runout of any circular surface of the test piece after installation is less than 0.1mm.

[0019] 4. The vibration amplitude standard in step (6) is that when the test piece reaches the maximum steady state speed, the vibration amplitude is less than 70μm.

[0020] 5. The calculation method of the normal temperature pre-rotation test speed in step (7) is:

[0021]

[0022] And The calculation is as follows:

[0023]

[0024] Wherein K1 and K2 are coefficients related to the structure and material performance of the wheel disc.

[0025] 6. The normal temperature pre-rotation test in step (7) requires that the wheel disc reaches the specified temperature and is kept for at least 1h before testing, and the wheel disc rotates at N R Speed for at least 1 minute;

[0026] After the test is completed, the wheel disc is cooled down, and when the wheel disc is thermally stable, the temperature is measured, the disc core hole diameter of the wheel disc is measured at the same position and in the same way as in step (1), and the average value is recorded as Duse, and the temperature when the size is measured is recorded as Te.

[0027] 7. The test qualification criterion for step (8) is that the difference in aperture growth measured at the center position of the disc before and after the rotation test, Duse-Dpp, is between 0.02 and 0.12 mm.

[0028] 8. 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.

[0029] Each diameter measurement should be added to the value Z:

[0030] Z=αD(T s -T e )

[0031] The difference in aperture growth after correction is denoted as:

[0032] Dxz = Duse - Dpp + Z.

[0033] 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

[0034] Figure 1 This is a flowchart of the present invention;

[0035] Figure 2 This is a schematic diagram of a gas turbine disk. Detailed Implementation

[0036] The invention will now be described in more detail with reference to the accompanying drawings:

[0037] Combination Figures 1-2 The present invention discloses a method for improving the service life of a gas turbine disk through a room-temperature overspeed pre-rotation test, the specific steps of which are as follows:

[0038] 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.

[0039] 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.

[0040] 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.

[0041] The dynamic balance standard is that the residual unbalance after dynamic balancing should be less than 100 g·mm.

[0042] Step 3: Perform rotor installation, connect the rotor test piece with the rotating tester through the intermediate connecting tool.

[0043] Step 4: Perform installation standard judgment, if the circular runout requirement is met, proceed to step 5, otherwise proceed to step 3.

[0044] 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.

[0045] Step 5: Perform normal temperature trial rotation.

[0046] Step 6: Perform vibration amplitude standard judgment, if the vibration standard is met, proceed to step 7, otherwise repeat step 1 to re-balance.

[0047] The vibration amplitude standard is that when the test piece reaches the maximum steady-state speed, the vibration amplitude is less than 70 μm.

[0048] Step 7: Perform normal temperature pre-rotation test, the key parameters of the test include normal temperature pre-rotation test speed, holding time before normal temperature pre-rotation test, holding time of normal temperature pre-rotation test speed, and normal temperature pre-rotation test temperature. Before the temperature reaches the required test temperature, low-speed rotation at a speed of 100-200 r / min is performed to ensure uniform cooling of the wheel disc.

[0049] The calculation method of the normal temperature pre-rotation test speed is: test speed N R is the minimum speed between and

[0050]

[0051] and are calculated as follows:

[0052]

[0053] where K1 and K2 are coefficients related to the structure and material properties of the wheel disc.

[0054] In the formula:

[0055] - yield limit of 0.2% at 20 degrees Celsius, unit: MPa.

[0056] - tensile limit at 20 degrees Celsius, unit: MPa.

[0057] ​Mechanical properties at 20°C temperature using a sample taken from the area close to the hole in the disc center.

[0058] The pre-rotation test at ambient temperature is preceded by a holding time of at least 1 h, and the holding time at the rotation speed of the pre-rotation test at ambient temperature is at least 1 min.

[0059] After the end of the test, the disc is cooled down and, when it is thermally stable, the temperature is measured and the diameter of the hole in the disc center is measured in the same way as in step 1, the average value being noted as Duse, and the temperature at which the dimension is measured is noted as Te.

[0060] Step 8: Analysis of the validity of the test results is performed, and if the test meets the requirements of the test acceptance criteria, the process is stopped, otherwise step 7 is repeated, and a new test rotation speed is selected for the pre-rotation test at ambient temperature.

[0061] The test acceptance criteria are that the difference in the increase in the diameter of the hole measured at the disc center before and after the rotation test (Duse-Dpp) must be between 0.02 and 0.12 mm.

[0062] If the temperature Te at which the dimension is measured after the test differs from the temperature Ts at which the dimension is measured before the rotation test by more than ± 5°C, it is necessary to take into account the thermal expansion of the disc material to correct the readings of the diameter measurements.

[0063] In this case, each diameter measurement value should be added to the value "Z":

[0064] Z = aD(Te-Ts) (4) s -T e ) (4)

[0065] where:

[0066] a is the linear expansion coefficient of the material, in °C -1 .

[0067] D is the nominal size of the diameter of the hole in the disc center, in mm.

[0068] Ts is the temperature at which the dimension is measured before the test, in °C.

[0069] Te is the temperature at which the dimension is measured after the test, in °C.

[0070] The corrected difference in the increase in the diameter of the hole is then:

[0071] Dxz = Duse-Dpp + Z (5).

Claims

1. A method for room temperature overspeed pre-rotation test to improve the service life of gas turbine disks, 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) Conduct a room temperature pre-rotation test; The calculation method for the rotation speed in the room temperature pre-rotation test is as follows: and The calculation is as follows: K1 and K2 are coefficients that are related to the disk structure and material properties. - Yield strength of 0.2% at 20 degrees Celsius, in MPa; - Tensile limit 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 room temperature pre-rotation test, the heat preservation time before the room temperature pre-rotation test shall be at least 1 hour, and the load holding time of the rotation speed in the room temperature pre-rotation test shall be at least 1 minute. (8) Analyze the validity of the test results. If the test results meet the qualification standards, stop the test. If they do not meet the standards, repeat step (7) and reselect the test speed to conduct a room temperature pre-rotation test.

2. The method for improving the service life of a gas turbine disk through room temperature overspeed pre-rotation test 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 method for improving the service life of a gas turbine disk using a room-temperature overspeed pre-rotation test 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 method for improving the service life of a gas turbine disk using a room-temperature overspeed pre-rotation test 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 method for improving the service life of a gas turbine disk through room temperature overspeed pre-rotation test 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 method for improving the service life of a gas turbine disk through room temperature overspeed pre-rotation test according to claim 1, characterized in that: Step (7) Room temperature 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. R Rotate at a speed of 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.

7. The method for improving the service life of a gas turbine disk through room temperature overspeed pre-rotation test according to claim 1, characterized in that: The test qualification criterion for step (8) is that the difference in aperture growth measured at the center of the wheel before and after the rotation test, Duse-Dpp, is between 0.02 and 0.12 mm.

8. The method for improving the service life of a gas turbine disk using a room-temperature overspeed pre-rotation test according to claim 7, 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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