A rotating fatigue test device and method for realizing a gradient temperature field of a turbine blade

Abstract

The present invention discloses a rotational fatigue test apparatus and method for achieving a gradient temperature field for turbine blades. The apparatus and method comprise a high-speed rotation test bench, an electromagnetic induction power supply, an induction heating coil, a cooling hood, a cooling water pipe, a circulating cooling water machine, a thermocouple, and a temperature display. The apparatus utilizes the electromagnetic induction heating principle of metals and employs a rationally designed induction device to achieve local heating of the turbine blade crown under high-speed rotation. After the local temperature of the crown rises, the temperature of the key test area at the blade root changes through heat conduction. The current and frequency of the induction heating coil are adjusted to precisely control the blade temperature to meet the test requirements. Simultaneously, circulating water cooling devices are arranged on the upper and lower sides of the turbine disk to ensure that a gradient temperature field is formed between the blades and the turbine disk. This ensures that the material strength of the turbine disk meets the standard under high-speed rotation and does not cause low-cycle fatigue failure before the blades. The apparatus can be used for rotational fatigue testing of gradient temperature fields in aircraft engine gas turbine blades.

Description

Technical Field

[0001] The present invention relates to a rotation fatigue test device and method for realizing a gradient temperature field of an aero-engine turbine blade, and is used in the field of high-temperature rotation fatigue testing of aero-engine turbine blades. Background Art

[0002] An aircraft engine's gas turbine rotor consists of a turbine disc, a turbine shaft, and turbine blades. The turbine blades are key components for converting high-temperature combustion gases into mechanical energy. During operation, they are not only surrounded by constantly changing high-temperature combustion gases, generating thermal stress, but also endure the enormous centrifugal stress, aerodynamic forces, and vibration loads caused by high-speed rotation. This harsh operating environment makes gas turbine blades a key component in determining the lifespan of aircraft engines. Blade failure can have extremely serious consequences, making the structural strength of turbine blades extremely important.

[0003] Aircraft engines experience numerous start-stop cycles during their service life, which can lead to so-called low-cycle fatigue. Given the high-temperature operating conditions of turbine blades, low-cycle fatigue testing under these conditions is necessary. Given the simultaneous presence of high temperatures and high centrifugal stresses in high-temperature, low-cycle fatigue testing of turbine blades, three main testing methods are currently available: dummy testing, test bench testing, and high-speed rotating test bench testing. The main drawbacks of dummy testing are the difficulty in dummy design, which differs from the geometry, process, and stress state of actual turbine rotor blades. Coupon testing on an engine test bench can accurately simulate the stress and temperature fields of blades. However, test bench testing requires blades to be evenly distributed around the turbine disk. Fatigue failure of a single blade can lead to collisions with other blades in the casing, causing numerous blade failures and damaging the casing. This results in a complex and costly testing process. Furthermore, the multitude of factors influencing blade failure during testing makes it difficult to specifically analyze the mechanisms of high-temperature, low-cycle fatigue. In the laboratory, high-speed rotating test benches can be used to conduct high-temperature, low-cycle rotating fatigue testing of blades. A small number of symmetrical blades can be placed on the turbine disk and counterweights can be added. This reduces testing costs and facilitates post-test analysis of blade failure modes. At this time, in order to simulate the high-temperature operating state of the blades, the gas turbine rotor needs to be placed in a high-temperature furnace as a whole, and the turbine disk and blades need to be heated to the same temperature. However, when the turbine blade rotor is actually working, there is a gradient temperature field where the blade temperature is higher and the turbine disk temperature is lower. Due to the distribution characteristics of this gradient temperature field, the material used in the actual turbine disk is different from the blade material, and its applicable temperature range is lower than the actual temperature of the blade. If the turbine disk and blades that are the same as those in the actual situation are used in the test, the turbine disk may fail due to low-cycle fatigue before the blade, thus failing to achieve the purpose of assessing the low-cycle fatigue life of the blades and causing the test to fail. If the same material as the blade is used to make the test turbine disk, it will not only be inconsistent with the actual structure of the engine, but will also significantly increase the test cost and extend the test period.

[0004] It can be seen that the gradient temperature field of the turbine blade rotor cannot be achieved in the current high-temperature and low-cycle rotation fatigue test of aircraft engine turbine rotor blades, which leads to huge test costs and low test efficiency, and may even cause the turbine disk to fail prematurely before the blades. Summary of the Invention

[0005] In response to the shortcomings of existing testing technologies, the present invention creatively proposes to achieve a gradient temperature distribution feature from the top of the blade to the root of the blade to the turbine disk by performing local induction heating at the blade crown, thereby providing a rotation fatigue test device and method that can be used for the gradient temperature field of aero-engine gas turbine blades. The basic principle of the present invention is to utilize the electromagnetic induction heating principle of metals and to achieve local heating of the turbine blade crown under high-speed rotation by designing a rationally designed induction device. After the local temperature of the blade crown rises, the temperature of the key test area at the root of the blade changes through heat conduction. The current and frequency of the induction heating coil are adjusted to achieve precise control of the blade temperature to meet the test requirements. At the same time, circulating water cooling devices are arranged on the upper and lower sides of the turbine disk to ensure that the blades and the turbine disk form a gradient temperature field, ensuring that the material strength of the turbine disk meets the standard under high-speed rotation and does not cause low-cycle fatigue failure before the blades.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A rotating fatigue test device for realizing a gradient temperature field of a turbine blade comprises a high-speed rotating test bench, an electromagnetic induction power supply, an induction heating coil, a cooling cover, a cooling water pipe, a circulating cooling water machine, a thermocouple and a temperature display;

[0008] The high-speed rotation test bench includes a test chamber surrounded by a cover plate and a base, a motor, a speed-increasing head, a core shaft, a turbine disc, and turbine blades. One end of the speed-increasing head is connected to the motor, and the other end extends through the opening in the center of the cover plate into the test chamber and is connected to the core shaft via a connector. The turbine disc is mounted on the core shaft and is fixed to the turbine blades by mortise and tenon joints.

[0009] The outer ring of the turbine blade is provided with an annular induction heating coil with an opening; the annular induction heating coil with an opening is fixed by a bracket on the base and connected to a variable frequency induction power supply outside the test chamber;

[0010] A cooling shroud is provided around the turbine disc and fixed to the test chamber via a support base. A cooling water pipe is wound around the outer wall of the cooling shroud and connected to a circulating water chiller outside the test chamber.

[0011] Thermocouples are installed on the side wall of the turbine blade, the turbine disk and the surface of the cooling cover near the turbine blade, and the thermocouple leads are connected to the temperature display outside the test cavity.

[0012] Preferably, the distance from the annular induction heating coil with an opening to the top of the turbine blade is 1.8 to 5.8 mm, preferably 1.8 to 3.8 mm.

[0013] Preferably, the cover plate of the high-speed rotation test bench is provided with a through hole for the cooling water pipe to pass through, and the through hole is filled with insulating glue.

[0014] Preferably, the annular induction heating coil with an opening includes an upper and lower double-layer induction copper tube wound into a 4 / 5 to 5 / 6 circular shape, and the double-layer induction copper tube is formed by winding an induction copper tube back and forth; a U-shaped magnetic beam device is arranged around the induction copper tube, and the opening of the U-shaped magnetic beam device is inward; an insulating upper fixing plate and a lower fixing plate are respectively provided above and below the induction copper tube, and the upper and lower fixing plates are fastened by bolts.

[0015] Preferably, a mounting hole is provided on the cover plate of the high-speed rotation test bench, an insulating flange is installed at the mounting hole, a joint for connecting the induction copper tube in the induction heating coil is provided on the insulating flange, and the variable frequency induction power supply is connected to the joint of the induction copper tube.

[0016] Preferably, the cooling cover includes an upper cooling cover and a lower cooling cover, the upper cooling cover is sleeved on the outer periphery of the outer wall of the turbine disk located above the turbine blades, and the lower cooling cover is sleeved on the outer periphery of the outer wall of the turbine disk located below the turbine blades; the upper cooling cover and the lower cooling cover are respectively fixed in the test cavity through support seats.

[0017] Preferably, the inner walls of the upper cooling cover and the lower cooling cover are parallel to the outer wall of the turbine disk, and the gap between the inner walls of the upper and lower cooling covers and the outer wall of the turbine disk is 2 to 8 mm, preferably 2 to 4 mm.

[0018] Preferably, the cooling cover and the cooling water pipe are made of copper.

[0019] The present invention has the following beneficial effects:

[0020] 1) The present invention uses an induction heating coil to heat a local position of the blade crown, causing the local temperature to rise rapidly; under the action of heat conduction, the heat expands toward the blade root and the turbine disk, fundamentally realizing the temperature gradient field distribution characteristics of the entire rotor. The insulating flange on the cover plate ensures that the induced magnetic field of the induction heating coil will not produce a significant induction heating effect on the cover plate when passing through the cover plate. The variable frequency induction power supply has its own current and power display, which can monitor the current and power changes of the induction coil; during the test, the induction frequency or current can be adjusted to change the temperature field at the local position of the blade, thereby achieving precise control of the temperature of the blade test part.

[0021] 2) This invention incorporates a cooling shroud mounted on the outer wall of the turbine disk. This shroud is fixed within the test chamber and does not rotate with the turbine disk. Copper pipes are wrapped around the shroud, through which cold water flows to remove heat radiated from the turbine disk, thereby reducing the turbine disk temperature. A circulating water chiller, by varying the pressure differential within the water pipes, ensures a sufficient flow rate of cold water within the pipes to remove sufficient heat, further ensuring the characteristic gradient temperature distribution of the turbine rotor.

[0022] 3) The present invention arranges multiple thermocouples for detecting the temperature at typical positions of the turbine disk and turbine blades as rotor gradient temperature field detection parameters; since the thermocouples on the turbine disk and turbine blades cannot rotate with the turbine disk, the present invention also arranges thermocouples at reference positions on the cooling cover. Through the relationship between the temperature values ​​at different positions on the turbine disk, turbine blades and cooling cover, the temperature on the turbine disk and turbine blades can also be regulated by the reference temperature value on the cooling cover during the test, thereby ensuring the stability of the temperature field during the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of the turbine blade gradient temperature field rotation fatigue test device;

[0024] Figure 2 (a) is a schematic diagram of the induction heating coil structure;

[0025] Figure 2 (b) is the schematic diagram of the induction heating coil;

[0026] Figure 3 It is a structural diagram of the cooling cover and cooling water pipe;

[0027] Figure 4 Schematic diagram of thermocouple arrangement position;

[0028] Figure 5 This is a curve diagram of temperature and speed changes during the blade rotation fatigue test;

[0029] Figure 6 This is the temperature field distribution diagram after local heating of the blade crown;

[0030] In the figure, 1. vacuum chamber cover, 2. small support base, 3. large support base, 4. small mounting ring, 5. turbine blade, 6. large mounting ring, 7. thermocouple lead, 8. thermocouple, 9. fixing bracket, 10. speed increasing head, 11. flexible shaft, 12. turbine disk, 13. cooling water pipe, 14. cooling cover, 15. induction heating coil, 16. induction coil lead, 17. temperature display, 18. variable frequency induction power supply, 19. circulating chiller, 20. fixing nut, 21. insulating flange, 22. induction copper tube, 23. insulating fixing plate, 24. magnetic beam device, 25. upper cooling cover, 26. lower cooling cover, 27. tester base, 28. adapter core shaft. DETAILED DESCRIPTION

[0031] Based on the principles of induction heating and water cooling, the present invention designs a device for performing a rotational fatigue test on a turbine blade rotor using a gradient temperature field. The heating and cooling system comprises an induction heating coil, a variable-frequency induction power supply, a circulating water chiller, a cooling hood, and a cooling water pipe, while the temperature monitoring system comprises a thermocouple and a temperature display. A through-hole for connecting the induction heating coil and the cooling water pipe is reserved on the vacuum chamber cover of the high-speed rotation test bench. The induction heating coil is designed with an open annular loop to heat the blade crown of the turbine blade and is connected to the variable-frequency induction power supply outside the chamber via an insulating flange on the cover. The cooling water pipe is connected to the chiller outside the chamber via a through-hole filled with insulating glue to prevent air leakage. Depending on the test requirements, the thermocouple is arranged at different locations and led out of the test chamber via thermocouple leads and connected to a temperature display. The present invention is further described below with reference to the accompanying drawings and examples.

[0032] like Figure 1 As shown, a rotating fatigue test device for realizing a gradient temperature field of an aircraft engine gas turbine blade mainly includes an induction heating coil 15, a cooling cover 14, a thermocouple 8 and its lead, a variable frequency induction power supply 18, a cooling water machine 19, a temperature display 17, a turbine disk 12 and a turbine blade 5.

[0033] The cover plate 1 and the tester base 27 form a test chamber, which is evacuated during the test to form a vacuum chamber. The tester base is cylindrical with a circular cross-section. The large mounting ring 6 is removably screwed to the bottom surface of the large support base 3. The top surface of the large support base 3 is screwed to the vacuum chamber cover plate 1. A rubber ring is installed between the vacuum chamber cover plate and the tester base to ensure a good seal. The speed increasing head 10 extends into the test chamber through the opening in the center of the vacuum chamber cover plate and is connected to the adapter core shaft 28 via a flexible shaft 11. The turbine disk is mounted on the core shaft and fixed to the turbine blades by mortise and tenon joints.

[0034] An induction heating coil 15 is installed around the turbine blade's periphery. A mounting bracket 9 is attached to the large mounting ring. The induction heating coil 15 is mounted on this bracket at the same height as the turbine blade. The wires of the induction heating coil 15 pass through the vacuum chamber cover and connect to an external variable-frequency induction power supply 18. Powered by a 220V voltage, it can generate up to 48kW of heating power, rapidly raising the temperature of a localized area on the blade's top from room temperature to over 800°C.

[0035] A cooling shroud is fitted around the outer periphery of the turbine disc, secured within the test chamber via a support base. A cooling water pipe is wrapped around the outer wall of the cooling shroud. The cooling shroud 14 and cooling water pipe 13 are both made of copper and welded together. They are secured to the test chamber of the rotary test bench via screws to a small support base 2, a small mounting ring 4, and a large mounting ring 6. A hole is drilled in the vacuum chamber cover to allow the cooling water pipe to be routed out, connecting it to an external circulating chiller 19, thus forming a cooling water loop. Thermocouples 8 are welded to the sidewalls of the turbine blade root and the cooling shroud to monitor temperature changes at various locations during induction heating. Thermocouple leads 7 pass through the vacuum chamber cover and connect to a temperature display outside the test chamber.

[0036] The high-speed rotation test bench is equipped with a variable-frequency induction power supply (18), a circulating water chiller (19), and a temperature display (17). The temperature display (17) displays the real-time temperature measured by multiple thermocouples at different locations and outputs a 4-20mV voltage signal. The variable-frequency induction power supply (18) adjusts the heating effect by varying the power level. Connecting to the voltage signal output by the temperature display (17), it also monitors temperature changes in real time, enabling automatic power control. The circulating water chiller (19) adjusts the cooling capacity of the cooling hood by controlling the circulating water flow rate.

[0037] As a preferred embodiment of the present invention, a through hole for the cooling water pipe to pass through is provided on the vacuum chamber cover, and the through hole is filled with insulating glue to prevent air leakage.

[0038] As a preferred embodiment of the present invention, Figure 2 As shown in (a), the annular induction heating coil with an opening includes a double-layer induction copper tube wound into a 4 / 5 to 5 / 6 ring shape, wherein the opening facilitates the placement and observation of thermocouples on the blades. An opening that is too small will make it difficult to install and test the thermocouples, while an opening that is too large will reduce the overall heating efficiency of the coil. The double-layer copper tube is formed by winding a copper tube back and forth, and a U-shaped magnetic beam device with an inward opening is arranged around the copper tube; the double-layer copper tube and the U-shaped magnetic beam device can ensure that the generated magnetic field is concentrated in a local position of the copper tube, and can only heat the top of the blade but not the entire turbine disk. The local magnetic field distribution is as shown in FIG. Figure 2 As shown in (b), there is no magnetic field at the center of the coil. The induction copper tube is secured with an upper insulating plate and a lower insulating plate above and below it, respectively, secured together by bolts. The insulating flange connected to the induction copper tube is mounted on the mounting hole in the vacuum chamber cover. The insulating flange is equipped with a connector for connecting to the induction copper tube in the induction heating coil and is connected to the variable frequency induction power supply outside the test chamber via a fixing nut.

[0039] As a preferred embodiment of the present invention, Figure 3As shown, the cooling cover includes an upper cooling cover 25 and a lower cooling cover 26. The upper cooling cover is sleeved on the periphery of the outer wall of the turbine disk located above the turbine blades, and the lower cooling cover is sleeved on the periphery of the outer wall of the turbine disk located below the turbine blades. The upper cooling cover and the lower cooling cover are respectively fixed in the test cavity by a small mounting ring 4 and a large mounting ring 6. The small mounting ring is connected to the vacuum chamber cover plate through a small support base 2. The inner walls of the upper cooling cover and the lower cooling cover are parallel to the outer wall of the turbine disk, and are made of copper. The gap between them and the outer wall of the turbine disk is 2-8 mm. Cooling water pipes 13 are evenly arranged on the outer walls of the upper cooling cover and the lower cooling cover, and the cooling water pipes are made of copper.

[0040] The gradient temperature field rotation fatigue test method based on the principles of induction heating and circulating water cooling implemented by the above-mentioned device includes the following steps:

[0041] 1) The structure and size of the induction heating coil and cooling cover are determined according to the size of the turbine disk with blades. The distance between the induction coil and the top of the blade is 2 mm, and the distance between the cooling cover surface and the turbine disk surface is 4 mm. The induction coil is designed as a 4 / 5 ring and a magnetic field device 24 is wrapped around the induction copper tube. Figure 2 As shown, to ensure that the magnetic induction line can only heat the local position of the blade tip; design the insulating flange 21 to prevent the induction coil from heating the vacuum chamber cover; design the insulating fixing plate 23 to ensure the roundness of the induction coil.

[0042] 2) Weld multiple thermocouples to different parts of the blades and turbine disks, such as Figure 4 As shown in the figure, a thermocouple is placed at the top, middle, and root of the blade, and a thermocouple is placed at the tongue and web of the turbine disk. A thermocouple is welded to the cooling shroud as a reference thermocouple.

[0043] 3) Install the bladed turbine disk onto the test bench core shaft, fix the induction coil and cooling cover inside the test cavity, and adjust the gap so that the relative positions of the three are reasonable. The installation height of the induction heating coil is consistent with the installation height of the turbine blade.

[0044] 4) Lead the thermocouple lead 7, cooling water pipe 13 and induction heating coil 15 through the vacuum chamber cover to the external temperature display 17, circulating water chiller 19 and variable frequency induction power supply 18, and perform vacuum sealing at the corresponding positions of the vacuum chamber cover.

[0045] 5) Turn on the variable frequency induction power supply and circulating water chiller, and observe the thermocouple temperature readings on the temperature display. If the turbine blade temperature is too low, increase the induction current. If the turbine disk temperature is too high, increase the cooling water flow. When the test area temperature reaches the target temperature, record the blade, turbine disk, and reference location temperatures.

[0046] 6) Stop heating, remove the thermocouples on the turbine blades and turbine disk, retain the reference position thermocouple on the cooling cover, turn on the high-speed rotation test bench, and adjust the variable frequency induction power supply current / power and cooling water flow rate under the high-speed rotation state of the turbine blades to make the reference position temperature meet the standard.

[0047] 7) Ensure that the temperature remains constant and officially start the rotation fatigue test. When the target number of cycles is reached or the sample is damaged, the fatigue test ends and the variable frequency induction power supply and circulating chiller are turned off. The temperature and speed change curves during the test are as follows: Figure 5 As shown, the dotted line represents the temperature value of the reference position on the cooling cover, and the solid line represents the rotational speed of the turbine disk. When the temperature value of the reference position reaches the target temperature and is in a stable state, the fatigue test begins. The speed increaser is controlled to accelerate first, then stabilize, and then decelerate. When the fatigue test is over, the turbine disk stops rotating, and the variable frequency induction power supply is turned off, causing the reference position to start cooling down until it reaches normal temperature.

[0048] In the present invention, the test blade material is DZ125 high temperature alloy, the operating temperature of which can reach above 1000°C, while the turbine disk material is GH4169, the normal operating temperature of which is below 650°C. Figure 6 It shows the temperature field distribution from the top of the blade to the blade tenon after the blade top is induction heated and the turbine disk is cooled by circulating water. Figure 6 It can be seen that under the heating and cooling device of the present invention, an obvious gradient temperature field is formed on the blade along the blade body height. The temperature below the edge plate, especially the tenon area, is significantly reduced to below 600°C, thereby ensuring that the temperature at the connection between the turbine disc tenon groove and the tenon, as well as the sub-plate and the core shaft meet the use requirements of material GH4169.

Claims

1. A rotating fatigue test device for realizing a gradient temperature field of a turbine blade, characterized in that: It includes high-speed rotating test bench, variable frequency induction power supply, induction heating coil, cooling cover, cooling water pipe, circulating chiller, thermocouple and temperature display; The high-speed rotation test bench includes a test chamber surrounded by a cover plate and a base, a motor, a speed-increasing head, a core shaft, a turbine disc, and turbine blades. One end of the speed-increasing head is connected to the motor, and the other end extends through the opening in the center of the cover plate into the test chamber and is connected to the core shaft via a connector. The turbine disc is mounted on the core shaft and is fixed to the turbine blades by mortise and tenon joints. The outer ring of the turbine blade is provided with an annular induction heating coil with an opening; the annular induction heating coil with an opening is fixed by a bracket on the base and connected to a variable frequency induction power supply outside the test chamber; the annular induction heating coil with an opening includes an upper and lower double-layer induction copper tube wound into a 4 / 5 to 5 / 6 circular shape, and the double-layer induction copper tube is formed by winding a single induction copper tube back and forth; a U-shaped magnetic beam device is arranged around the induction copper tube, with the opening of the U-shaped magnetic beam device facing inward; an insulating upper fixing plate and a lower fixing plate are respectively provided above and below the induction copper tube, and the upper and lower fixing plates are fastened together by bolts; A cooling shroud is provided around the turbine disc and fixed to the test chamber via a support base. A cooling water pipe is wound around the outer wall of the cooling shroud and connected to a circulating water chiller outside the test chamber. Thermocouples are installed on the side wall of the turbine blade, the turbine disk and the surface of the cooling cover near the turbine blade, and the thermocouple leads are connected to the temperature display outside the test cavity.

2. A rotating fatigue testing device for realizing a gradient temperature field of a turbine blade according to claim 1, characterized in that: The distance between the annular induction heating coil with the opening and the top of the turbine blade is 1.8 to 5.8 mm.

3. The rotating fatigue testing device for realizing a gradient temperature field of a turbine blade according to claim 1, characterized in that: The cover plate of the high-speed rotation test bench is provided with a through hole for the cooling water pipe to pass through, and the through hole is filled with insulating glue.

4. The rotating fatigue testing device for realizing a gradient temperature field of a turbine blade according to claim 1, characterized in that: The cover plate of the high-speed rotation test bench is provided with a mounting hole, an insulating flange is installed at the mounting hole, a joint for connecting the induction copper tube in the induction heating coil is provided on the insulating flange, and the variable frequency induction power supply is connected to the joint of the induction copper tube.

5. The rotating fatigue testing device for realizing a gradient temperature field of a turbine blade according to claim 1, characterized in that: The cooling cover includes an upper cooling cover and a lower cooling cover. The upper cooling cover is sleeved on the outer periphery of the outer wall of the turbine disk located above the turbine blades, and the lower cooling cover is sleeved on the outer periphery of the outer wall of the turbine disk located below the turbine blades. The upper cooling cover and the lower cooling cover are respectively fixed in the test cavity through support seats.

6. The rotating fatigue testing device for realizing a gradient temperature field of a turbine blade according to claim 5, characterized in that: The inner walls of the upper cooling cover and the lower cooling cover are parallel to the outer wall of the turbine disk, and the gap between the inner walls of the upper cooling cover and the lower cooling cover and the outer wall of the turbine disk is 2 to 8 mm.

7. The rotating fatigue testing device for realizing a gradient temperature field of a turbine blade according to claim 1, characterized in that: The cooling cover and the cooling water pipe are made of copper.

8. A method for performing a rotation fatigue test on a turbine blade using the rotation fatigue test apparatus of claim 1, characterized in that The following steps are involved: 1) Design the induction heating coil, determine the distance from the induction heating coil to the top of the turbine blade to be 1.8 to 5.8 mm, and arrange the magnetic field device in the induction heating coil; 2) Design the cooling shroud according to the turbine disk structure, ensuring that the surface of the cooling shroud is parallel to the surface of the turbine disk, and that the gap between the inner wall of the cooling shroud and the outer wall of the turbine disk is 2 to 8 mm; evenly wind the cooling water pipe around the cooling shroud; 3) Secure the bladed turbine disk, cooling cover, and induction heating coil within the test chamber of the high-speed rotation test bench, with the induction heating coil and turbine blade installed at the same height. Drill a hole in the cover of the high-speed rotation test bench and install an insulating flange. Lead out the induction copper tube of the induction heating coil and install a connector for the induction copper tube on the insulating flange. Connect the connector to the variable frequency induction power supply. Drill a hole in the cover to connect the cooling water pipe to the circulating chiller. 4) Arrange thermocouples on the sidewalls of the turbine blades, on the turbine disc, and on the surface of the cooling shroud near the turbine blades. The temperature values ​​of the thermocouples on the turbine blades and turbine disc serve as the measured values, and the temperature value of the thermocouple on the cooling shroud serves as the reference value. With the turbine disc stationary, adjust the heating and cooling efficiencies by varying the parameters of the variable frequency induction power supply and the flow rate of the circulating chiller so that the temperature values ​​of the thermocouples on the turbine blades and turbine disc meet the test requirements. Measure the relationship between the temperature values ​​of the thermocouples, and record the operating parameters of the variable frequency induction power supply and the circulating chiller. 5) Keep the parameters of the variable frequency induction power supply and circulating chiller unchanged, remove the thermocouples arranged on the turbine disc and turbine blades, evacuate the test chamber, and start the high-speed rotation test bench to rotate the rotor at high speed; During the stable rotation of the rotor, record the temperature value of the thermocouple on the cooling cover and compare it with the temperature value of the same reference position in the static state. If there is a difference, fine-tune the operating parameters of the variable frequency induction power supply and the circulating chiller to make them the same; 6) Record the corresponding test parameters and formally carry out the rotation fatigue test of the turbine blade under the gradient temperature field. After reaching a specific number of cycles or blade failure, turn off the variable frequency induction power supply and circulating chiller.

9. The method for realizing a rotation fatigue test of a turbine blade gradient temperature field according to claim 8, characterized in that: The cooling cover includes an upper cooling cover and a lower cooling cover. The upper cooling cover is sleeved on the outer wall of the turbine disk above the turbine blades, and the lower cooling cover is sleeved on the outer wall of the turbine disk below the turbine blades. The upper cooling cover and the lower cooling cover are respectively fixed in the test cavity through support seats.

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