Cold-state overspeed pre-rotation test method for checking structural integrity of wheel disc of gas turbine

Abstract

The invention aims to provide a cold-state overspeed pre-rotation test method for checking the structural integrity of a wheel disc of a gas turbine, which belongs to the field of gas turbines and comprises the following steps of: sequentially carrying out rotor assembly and dynamic balance, rotor installation, normal-temperature test rotation, temperature field calibration and cold-state pre-rotation test, and finally carrying out test result validity analysis. Whether the wheel disc meets the structural integrity or not is determined, and during the period, dynamic balance standard judgment, installation standard judgment, vibration amplitude standard judgment and temperature field standard judgment are conducted respectively. The internal defects can be detected under the condition that the wheel disc is not damaged, and the reliability of the wheel disc is effectively improved.

Description

Technical Field

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

[0002] Ships and industrial gas turbines are developing towards higher power and larger size. In order to make the gas turbine have sufficient strength, the rotating parts of the impeller are often designed to be thick. The thick impeller will have internal defects (such as segregation and brittle areas containing hydrogen and sulfur, etc.), which cannot be detected by ordinary ultrasonic flaw detection. When the impeller works in extremely cold temperatures, the material will become brittle. At the operating speed, the crack defect may expand to a critical value and cause the impeller to break. The destructive energy of the impeller is huge when it rotates at high speed, which will have catastrophic consequences for ships, factories and personal safety. Therefore, it is particularly important to design a method to assess the structural integrity of the impeller.

[0003] The cold overspeed prestressing test technology for the wheel disc can expand the crack defects in advance during the overspeed process and cause the wheel disc with large defects to rupture; if the defects do not cause damage, the generated opening can be detected by subsequent non-destructive testing, thereby avoiding possible damage during use. Summary of the invention

[0004] The purpose of the present invention is to provide a cold overspeed pre-rotation test method for assessing the structural integrity of a gas turbine wheel, which can detect internal defects without damaging the wheel and effectively improve the reliability of the wheel.

[0005] The object of the present invention is achieved in that:

[0006] The present invention provides a cold overspeed pre-rotation test method for evaluating the structural integrity of a gas turbine wheel disc, which is characterized by comprising the following steps:

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

[0008] (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.

[0009] (3) Install the rotor;

[0010] (4) Determine the installation standard. If the circular runout requirement is met, proceed to step (5); if not, proceed to step (3);

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

[0012] (6) Determine the vibration amplitude standard. If the vibration standard is met, proceed to step (7). If not, repeat step (1) to perform dynamic rebalancing.

[0013] (7) Perform temperature field calibration;

[0014] (8) Perform temperature field standard judgment. If the temperature meets the required range, proceed to step (9); if not, repeat step (7);

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

[0016] (10) Conduct validity analysis of the test results to determine whether the wheel meets the structural integrity requirements.

[0017] The present invention may also include:

[0018] 1. Step (1) After the rotor is assembled, measure the diameter of the center hole of the disk: measure at least 3 different positions along the axial direction of the center hole of the disk. 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 multiple measured dimensions is recorded as Dpp, and the temperature when the dimensions are measured is recorded as Ts.

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

[0020] 3. The installation standard of 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 vibration amplitude standard of step (6) is that the vibration amplitude of the test piece is less than 70 μm when it reaches the maximum steady-state speed.

[0022] 5. The temperature standard of step (8) is that the absolute value of the difference between the calibration temperature and the required temperature is less than 10°C.

[0023] 6. Step (9) Cold pre-rotation test speed N C The calculation method is:

[0024]

[0025] Where K is a coefficient, which is related to the wheel structure and material properties.

[0026] 7. Step (9) The cold pre-rotation test requires the following requirements: the wheel reaches the specified temperature and is kept warm for at least 3 hours before the test. C Spin at high speed for at least 1 minute;

[0027] 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 at which the size is measured is recorded as Te.

[0028] 8. Step (10) The validity analysis of the test results is to perform nondestructive testing on all surfaces of the wheel disc after the rotation test. If no cracks are found, the wheel disc meets the structural integrity inspection. If cracks are found, the wheel disc is scrapped.

[0029] The advantage of the present invention is that the present invention can detect internal defects without damaging the wheel disc, thereby effectively improving the reliability of the wheel disc. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a flow chart of the present invention;

[0031] Figure 2 Schematic diagram of a gas turbine disc. DETAILED DESCRIPTION

[0032] The present invention is described in more detail below with reference to the accompanying drawings:

[0033] Combination Figure 1-2 The cold overspeed pre-rotation test method for evaluating the structural integrity of a gas turbine wheel disc of the present invention comprises the following specific steps:

[0034] 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.

[0035] After the rotor is assembled, Figure 2 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.

[0036] 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.

[0037] The dynamic balancing standard is that the residual unbalance after dynamic balancing should be less than 100g·mm.

[0038] Step 3: Install the rotor and connect the rotor test piece to the rotation tester through the intermediate connecting fixture.

[0039] Step 4: Determine the installation standard. If the circular runout requirement is met, proceed to step 5. If not, proceed to step 3.

[0040] The installation standard is that the circular runout of any circumferential surface of the test piece after installation must be less than 0.1mm.

[0041] Step 5: Perform a test run at room temperature.

[0042] 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.

[0043] The vibration amplitude standard is that the vibration amplitude is less than 70μm when the test piece reaches the maximum steady-state speed.

[0044] Step 7: Perform temperature field calibration.

[0045] Step 8: Make a temperature field standard judgment. If the temperature meets the required range, proceed to step 9. If not, repeat step 7.

[0046] The temperature standard is that the absolute value of the difference between the calibration temperature and the required temperature is less than 10°C.

[0047] Step 9: Conduct a cold pre-rotation test. The key parameters of the test include the cold pre-rotation test speed, the holding time before the cold pre-rotation test, the holding time of the cold pre-rotation test speed, and the cold pre-rotation test temperature. Before the temperature reaches the test requirement, the wheel should be operated at a low speed of 100 to 200 r / min to ensure that the wheel is cooled evenly.

[0048] The cold pre-rotation test speed N C The calculation method is:

[0049]

[0050] Where K is a coefficient, which is related to the wheel structure and material properties.

[0051] Where:

[0052] - 0.2% yield strength at 20 degrees Celsius, in MPa.

[0053] 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.

[0054] The cold pre-rotation test has the following requirements: the insulation time before the cold pre-rotation test must be at least 3 hours before the test can be carried out, and the holding time of the cold pre-rotation test speed must be at least 1 minute.

[0055] 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.

[0056] Step 10: Analyze the validity of the test results. Perform nondestructive testing 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 is scrapped.

Claims

1. A cold overspeed pre-rotation test method for evaluating the structural integrity of a gas turbine disk, 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 perform dynamic rebalancing. (7) Perform temperature field calibration; (8) Perform temperature field standard judgment. If the temperature meets the required range, proceed to step (9); if not, repeat step (7); (9) Conduct a cold pre-rotation test; (10) Conduct validity analysis of the test results to determine whether the wheel meets the structural integrity requirements.

2. A cold overspeed pre-rotation test method for evaluating the structural integrity of a gas turbine disk according to claim 1, characterized in that: Step (1) After the rotor is assembled, measure the diameter of the center hole of the disk: measure at least 3 different positions along the axial direction of the center hole of the disk, and 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 multiple measured dimensions is recorded as Dpp, and the temperature when the dimensions are measured is recorded and recorded as Ts.

3. The cold overspeed pre-rotation test method for gas turbine disk structural integrity assessment according to claim 1 is characterized by: The dynamic balancing standard of step (2) is that the residual unbalance after dynamic balancing should be less than 100 g·mm.

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

6. A cold overspeed pre-rotation test method for evaluating the structural integrity of a gas turbine disk according to claim 1, characterized in that: The temperature standard of step (8) is that the absolute value of the difference between the calibration temperature and the required temperature is less than 10°C.

7. The cold overspeed pre-rotation test method for gas turbine disk structural integrity assessment according to claim 1 is characterized by: Step (9) Cold pre-rotation test speed N C The calculation method is: Where K is a coefficient, which is related to the wheel structure and material properties.

8. The cold overspeed pre-rotation test method for evaluating the structural integrity of a gas turbine disk according to claim 1, characterized in that: Step (9) The cold pre-rotation test requires the following requirements: the wheel reaches the specified temperature and is kept warm for at least 3 hours before the test. C Spin at high speed for at least 1 minute; 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 at which the size is measured is recorded as Te.

9. The cold overspeed pre-rotation test method for evaluating the structural integrity of a gas turbine disk according to claim 1, characterized in that: Step (10) The validity analysis of the test results is to perform non-destructive testing on all surfaces of the wheel disc after the rotation test. If no cracks are found, the wheel disc meets the structural integrity inspection. If cracks are found, the wheel disc is scrapped.

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