Thermal-state overspeed pre-rotation test method for prolonging service life of wheel disc of gas turbine

Abstract

The invention aims to provide a thermal-state overspeed pre-rotation test method for prolonging the service life of a gas turbine wheel disc, which belongs to the field of gas turbines, and comprises the following steps: sequentially carrying out rotor assembly and dynamic balance, rotor installation, normal-temperature test rotation, temperature field calibration and thermal-state pre-rotation test, and finally carrying out test result validity analysis. And if the size requirement is met, stopping, if the size requirement is not met, repeating the steps, reselecting the test rotating speed, and respectively performing dynamic balance standard judgment, installation standard judgment, vibration amplitude standard judgment and temperature field standard judgment during the period. The service life of the wheel disc can be effectively prolonged, and the production cost of the wheel disc is reduced.

Description

Technical Field

[0001] The present invention relates to a gas turbine test method, in particular to a wheel disc test 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, its impeller rotating parts are often designed to be thick, which greatly increases its production and manufacturing costs. At the same time, its size also greatly occupies the limited space of ships and factories. The impeller generally works in a high temperature, high pressure, and high speed working environment, and is subjected to the combined effects of various loads such as centrifugal force and thermal stress attached to itself and the blades. Its destructive energy is huge, which will have catastrophic consequences on ships, factories and personal safety. Therefore, how to design a method to effectively increase the life of the impeller is particularly important.

[0003] The hot overspeed prestressing test technology of the wheel can improve the stress distribution inside the wheel. The specific principle is that before the wheel is put into service, it rotates at a higher speed than the speed during service operation, so that the stress of 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 part that has undergone plastic deformation 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 of 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. Summary of the invention

[0004] The object of the present invention is to provide a hot overspeed pre-rotation test method for increasing the service life of a gas turbine wheel, which can effectively increase the service life of the wheel and reduce the production cost of the wheel.

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

[0006] The present invention provides a hot overspeed pre-rotation test method for improving the service life 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) Conducting a hot pre-rotation test;

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

[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, and measure the diameter twice at each position at 90° perpendicular to each other, and mark these positions on the disk. The average value of the measured dimensions is recorded as Dpp, and the temperature when the dimensions are measured is recorded as Ts.

[0019] 2. The dynamic balancing standard of step (2) is that the residual unbalance after dynamic balancing is 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) Hot pre-rotation test speed N H The calculation method is:

[0024]

[0025] and The calculation is as follows:

[0026]

[0027] Among them, A, B, and C are coefficients, which are related to the wheel structure and material properties.

[0028] 7. Step (9) Hot pre-rotation test requirements: After the wheel reaches the specified temperature, keep it warm for at least 1 hour before testing. H Spin at high speed for at least 1 minute;

[0029] 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.

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

[0031] 9. The difference in the aperture growth is considered as follows: 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:

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

[0033] Z = αD(T s -T e )

[0034] The difference in the corrected aperture growth is recorded as:

[0035] Dxz=Duse-Dpp+Z.

[0036] The advantages of the present invention are that the present invention can effectively increase the service life of the wheel disc and reduce the production cost of the wheel disc. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a flow chart of the present invention;

[0038] Figure 2 Schematic diagram of a gas turbine disc. DETAILED DESCRIPTION

[0039] The present invention is described in more detail below 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 wheel disc, and the specific steps are as follows:

[0041] 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.

[0042] 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.

[0043] 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.

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

[0045] Step 3: Install the rotor and connect the rotor test piece to the rotation tester through the intermediate connecting fixture.

[0046] Step 4: Determine the installation standard. If the circular runout requirement is met, proceed to step 5. If not, proceed to step 3.

[0047] The installation standard is that the circular runout of any circumferential surface of the test piece after installation must be less than 0.1mm.

[0048] Step 5: Perform a test run at room temperature.

[0049] 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.

[0050] The vibration amplitude standard is that the vibration amplitude is less than 70μm when the test piece reaches the maximum steady-state speed.

[0051] Step 7: Perform temperature field calibration.

[0052] Step 8: Make a temperature field standard judgment. If the temperature meets the required range, proceed to step 9. If not, repeat step 7.

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

[0054] Step 9: Conduct a hot pre-rotation test. The key parameters of the test include the hot pre-rotation test speed, the holding time before the hot pre-rotation test, the holding time of the hot pre-rotation test speed, and the hot pre-rotation test temperature. Before the temperature reaches the test requirement, it should be operated at a low speed of 100-200r / min to ensure that the wheel is heated evenly.

[0055] The calculation method of hot pre-rotation test speed is: test speed n H For between and The minimum speed between.

[0056]

[0057] and The calculation is as follows:

[0058]

[0059] Among them, A, B, and C are coefficients, which are related to the wheel structure and material properties.

[0060] Where:

[0061] - 0.02% yield strength at t degrees Celsius, in MPa.

[0062] - 0.2% yield strength at t degrees Celsius, in MPa.

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

[0064] The mechanical properties of the specimens collected from the area near the center hole of the disk at a temperature of t°C are used.

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

[0066] 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.

[0067] Step 10: Analyze the validity of the test results. If the test results meet the requirements of the test qualification standard, stop. If not, repeat step 9 and re-select the test speed to perform 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 wheel before and after the rotation test must be between 0.02-0.12mm.

[0069] 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.

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

[0071] Z = αD(T s -Te ) (4)

[0072] Where:

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

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

[0075] Ts is the temperature when the dimensions are measured before the test, in °C.

[0076] Te is the temperature when the dimensions are measured after the test, in °C.

[0077] The difference in the corrected aperture growth is recorded as:

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

Claims

1. A hot overspeed pre-rotation test method for improving the service life of a gas turbine wheel disc, 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) Conducting a hot pre-rotation test; (10) Analyze the validity of the test results. If the size requirements are met, stop the test. If not, repeat step (9) and reselect the test speed.

2. A 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, 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 measure the diameter twice at each position at 90° perpendicular to each other, and mark these positions on the wheel. The average value of the measured dimensions is recorded as Dpp, and the temperature when the dimensions are measured is recorded as Ts.

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

4. A 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 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. A hot overspeed pre-rotation test method for improving the service life of a gas turbine disk 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 hot overspeed pre-rotation test method for improving the service life 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. A 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 speed N H The calculation method 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.

8. A 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, keep it warm for at least 1 hour before testing. H 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. A 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) is that the difference Duse-Dpp of the aperture growth measured at the center of the wheel before and after the rotation test is between 0.02-0.12 mm.

10. A 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 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: Each diameter measurement should be added with the value Z: Z=αD(T s -T e ) The difference in the corrected aperture growth is recorded as: Dxz=Duse-Dpp+Z.

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