A turbine blade thermal-mechanical combined fatigue test device under rotating environment

Abstract

The present application belongs to the technical field of aero-engine high-temperature component test, and particularly relates to a kind of turbine blade rotating environment under thermo-mechanical complex fatigue test equipment, including high-temperature gas system, stator system, rotor system, support system, test system, auxiliary system, turbine rotor blade test piece, the high-temperature gas system is used to provide gas environment for turbine rotor blade test piece, and the high-low temperature cycle state of gas is controlled, its front end is equipped with combustion chamber, combustion chamber is equipped with double oil path nozzle, rear end is equipped with gas flow system, gas flow system is designed cascade structure according to turbine rotor blade geometry, and is equipped with spray cooling section in test section rear part.The present application is composed of six core systems of high-temperature gas system, stator system, rotor system, support system, test system and auxiliary system, each system works cooperatively, realizes the integration simulation of "high-temperature gas environment + rotating centrifugal load + heat-power synchronous cycle".

Description

Technical Field

[0001] This invention belongs to the field of high-temperature component testing technology for aero-engines, specifically relating to a thermomechanical composite fatigue testing device for turbine blades under rotating conditions. Background Technology

[0002] In the technological path to improve the performance of aero-engines, increasing the turbine inlet temperature is one of the core directions. The turbine inlet temperature of current advanced aero-engines has exceeded 1800K, approaching or even exceeding the limit temperature resistance of turbine rotor blade materials; at the same time, in pursuit of a higher thrust-to-weight ratio, turbine speed continues to increase, resulting in rotor blades bearing centrifugal loads of up to hundreds of MPa, becoming one of the main causes of blade failure.

[0003] Throughout the engine's lifecycle, turbine rotor blades undergo complex operating conditions including takeoff, cruise, landing, and maneuvering flight. The thermal and centrifugal loads they experience alternate periodically: during takeoff, the exhaust temperature rapidly rises to its peak, while the sudden increase in rotational speed causes a rapid increase in centrifugal force; during cruise, the load remains at a stable level; and during landing, the load rapidly decreases to its lowest point. This periodic thermo-mechanical coupling is the root cause of low-cycle fatigue damage in rotor blades, ultimately leading to fracture failure. According to aviation industry failure statistics, approximately 35% of in-flight engine shutdowns are directly related to turbine rotor blade fatigue failure. Therefore, conducting precise thermo-mechanical composite fatigue testing during the blade development stage is crucial.

[0004] Currently, the industry's testing methods for the fatigue performance of turbine rotor blades are mainly divided into three categories, but all of them have significant shortcomings:

[0005] Gas environment thermal shock test: This method generates high-temperature gas in the combustion chamber and introduces cooling air into the blade cavity to simulate wall temperature distribution. Thermal stress cycling is achieved by periodically adjusting the gas and air temperatures. However, it can only assess the effect of thermal load on stator components (such as guide vanes), completely ignoring the coupling effect of centrifugal force on the rotor blade temperature field distribution (such as changes in cooling channel flow caused by blade deformation due to centrifugal force) and stress state (superposition of centrifugal stress and thermal stress). Related studies show that the centrifugal stress amplitude of rotor blades can reach 3-5 times that of thermal stress; therefore, this method cannot accurately assess the fatigue life of rotor blades. Local high-temperature static thermomechanical test: High-frequency induction heating is used to simulate the temperature field of the blade's critical section, and uniaxial centrifugal force is simulated by hydraulic tension or weight loading. This method has three major drawbacks: First, it replaces the global gas scouring with local heating, ignoring the oxidation, corrosion and aerodynamic loads on the blade surface caused by the high-temperature gas; second, static loading requires additional stress-bearing fixtures to be machined at the blade tip, which changes the original blade structure and stress distribution; and third, uniaxial loading cannot simulate the gradient distribution of real centrifugal force (the stress at the blade root is 8-10 times that at the blade tip) and the bending-torsional coupling effect, resulting in a large deviation from actual working conditions.

[0006] Static thermomechanical test in gas environment: Although it can reproduce the gas scouring environment, it still uses static loading to simulate centrifugal force. It does not solve core issues such as the centrifugal force gradient effect under rotation and the influence of blade dynamic deformation on the thermal field. The correlation between the test data and the actual service condition is still weak.

[0007] In summary, existing testing equipment cannot simultaneously reproduce the real-world operating conditions of "high-temperature gas erosion + rotating centrifugal load + periodic load coupling," thus limiting the guiding value of test data for blade design. Therefore, developing a thermomechanical composite fatigue tester capable of accurately simulating the real service environment of turbine rotor blades has become an urgent need in the field of aero-engine development. Summary of the Invention

[0008] The purpose of this invention is to provide a thermo-mechanical composite fatigue testing device for turbine blades under rotating conditions. It consists of six core systems: a high-temperature gas system, a stator system, a rotor system, a support system, a testing system, and an auxiliary system. These systems work together to achieve integrated simulation of "high-temperature gas environment + rotating centrifugal load + thermo-mechanical synchronous cycle".

[0009] The specific technical solution adopted by this invention is as follows:

[0010] A thermomechanical composite fatigue testing device for turbine blades under rotating conditions includes a high-temperature gas system, a stator system, a rotor system, a support system, a testing system, an auxiliary system, and a turbine rotor blade test piece. The high-temperature gas system is used to provide a gas environment for the turbine rotor blade test piece and control the high and low temperature circulation state of the gas. It has a combustion chamber at the front end, which is equipped with a dual oil circuit nozzle, and a gas flow system at the rear end. The gas flow system is designed with a blade cascade structure according to the geometry of the turbine rotor blade, and a spray cooling section is provided at the rear of the test section.

[0011] The stator system is designed in conjunction with the rotor system, and is divided into multiple chambers, including a gas sealing chamber, an axial force adjustment chamber, and a fulcrum sealing chamber. The gas sealing chamber is vented with room temperature high-pressure air to seal off gas leakage into the chamber. The axial force adjustment chamber is vented with room temperature high-pressure air to adjust the aerodynamic force acting on the rotating disk. The fulcrum sealing chamber is used to suppress lubricating oil leakage from the fulcrum bearing. At the same time, the stator system works in conjunction with the determined turbine rotor blade test piece to control the blade tip clearance.

[0012] The rotor system includes a shaft system and a rotating disk. The rotating disk is connected to the shaft system through a clamping structure. The end of the shaft system is connected to a high-speed variable frequency motor. The high-speed variable frequency motor is used to control the rotational speed of the shaft system, thereby realizing the control of the centrifugal force on the turbine rotor blade test piece.

[0013] The support system is used to support the entire test apparatus and takes into account the expansion and deformation caused by the temperature of the rotating and stationary systems. The test system includes rotating system test equipment and stationary system test equipment. The rotating system test equipment includes a slip ring actuator and a dynamic pressure sensor. The stationary system test equipment includes a thermocouple, a pressure transmitter, and a flow meter, which are used to test relevant parameters during the test. The auxiliary system includes a control system, a circulating water system, a fuel system, and an exhaust muffler tower, which are used to cooperate with the above systems.

[0014] In a preferred embodiment, the combustion chamber is designed in a series, with design temperatures including 1000K, 1600K, and 1800K, and the corresponding combustion chamber is selected according to the specific requirements of the test.

[0015] In a preferred embodiment, the auxiliary oil nozzle supply circuit of the dual-oil-circuit nozzle uses an auxiliary oil pump whose speed is controlled by a variable frequency motor to provide continuous adjustment capability, and is controlled by a solenoid valve to increase the oil pressure to a level greater than the mainstream pressure before providing ignition fuel for ignition; the main oil nozzle supply circuit uses a regulating valve instead of a solenoid valve, and the high-temperature maintenance temperature level of the gas is determined by the oil pump speed and the stroke opening of the regulating valve. The regulating valve can control the stroke cycle of the regulating valve, so that the transition period time from low temperature to high temperature and from high temperature to low temperature is independently controllable.

[0016] In a preferred embodiment, the gas flow system consists of 3-5 blades in the cascade, the turbine rotor blade test piece is located in the middle of the cascade, and the gas flow system matches the blade tip clearance, inlet angle and exhaust angle parameters according to the flow field design requirements of the test blade. The inlet section of the test section is provided with temperature and pressure test parameter interfaces, and the exhaust section is provided with exhaust test parameter interfaces.

[0017] In a preferred embodiment, the design of the rotating disk includes two options: Option 1 uses a metal material, taking into account both edge cooling and strength reserves under centrifugal loads; Option 2 uses a composite material, specifically CMC material, which utilizes its temperature resistance to optimize the structural design. The diameter of the rotating disk meets the requirements of the rotor test blades, and the strength of the rotating disk meets the requirements for high temperature and high speed, while also possessing a certain strength reserve.

[0018] In a preferred embodiment, the shaft system is designed with a fulcrum at a suitable position, and the shaft system is designed with serrations and bosses to meet the sealing and positioning design requirements. The specific structure of the shaft system is determined according to the size of the rotating disk and the rotation speed requirements.

[0019] In a preferred embodiment, the high-speed variable frequency motor achieves adjustable and controllable centrifugal mechanical load by controlling the frequency conversion time between high and low speeds.

[0020] In a preferred embodiment, the testing system may also employ testing instruments such as infrared thermal imagers and wall temperature couplers, depending on the test conditions and the specific circumstances of the test specimen.

[0021] In a preferred embodiment, the high-temperature gas system cooperates with the rotor system to achieve synchronous loading of centrifugal force and thermal load, with the centrifugal force controlled by the rotation speed and the thermal load controlled by the gas temperature.

[0022] In a preferred embodiment, the composite load spectrum is divided into four stages: “heating loading (t1) – high temperature load maintenance (t2) – cooling unloading (t3) – low temperature load maintenance (t4)”, and the load size, rate and time are adjusted according to the task requirements.

[0023] The technical effects achieved by this invention are as follows:

[0024] High accuracy in reproducing operating conditions: For the first time, it realizes full-condition simulation of "high-temperature gas scouring + rotating centrifugal load + thermo-mechanical synchronous cycle", with centrifugal force gradient distribution error ≤5% and gas temperature control error ±10K, completely reproducing the real service environment of rotor blades, and the reliability of test data is improved by more than 60% compared with traditional equipment.

[0025] High load adjustment flexibility: Through the coordinated control of dual oil circuit nozzles and high-speed variable frequency motor, the heating rate (5-20K / min), cooling rate (3-15K / min), and heating / deceleration time (10-60s) can be independently adjusted, supporting 10-1000 cycle settings, adapting to the test requirements of turbine blades of different models and under different working conditions, and improving the equipment's versatility by 40%.

[0026] High operational safety: It adopts a three-stage sealing system (gas sealing chamber + axial force adjustment chamber + fulcrum sealing chamber) and spray cooling technology, with a gas leakage rate of <0.1% and a bearing operating temperature of ≤80℃. It is also equipped with multiple alarm mechanisms such as over-temperature, over-pressure, and low oil level, and there is no risk of safety accidents during the test process.

[0027] Comprehensive Test Data: Integrating multi-dimensional testing equipment such as slip ring actuators, infrared thermal imagers, and dynamic pressure sensors, it can simultaneously collect 18 types of parameters including temperature field, stress field, flow field, and rotational speed, with a data sampling rate of up to 10,000 Hz, providing complete data support for blade fatigue life assessment and design optimization. Significant Engineering Application Value: Before engine testing, this equipment can expose blade design defects in advance, reducing testing risks and costs; the test data can be used to verify rotating heat transfer models, constitutive models, and life prediction methods, promoting advancements in the design technology of high-temperature components for aero-engines and shortening the development cycle by more than 30%. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the composite load spectrum of a turbine blade thermomechanical composite fatigue testing device under rotating environment according to the present invention;

[0029] Figure 2 This is a schematic diagram of the overall design of a test apparatus for a turbine blade thermomechanical fatigue test under rotating conditions, according to the present invention.

[0030] Figure 3 This is a schematic diagram of the combustion chamber of a test apparatus for thermomechanical combined fatigue testing of turbine blades under rotating conditions, according to the present invention.

[0031] Figure 4 This is a schematic diagram of the dual oil circuit adjustment principle of the tester of the thermomechanical composite fatigue test equipment for turbine blade rotation environment according to the present invention;

[0032] Figure 5 This is a schematic diagram of the test blade cascade of a turbine blade thermomechanical fatigue testing device under rotating environment according to the present invention;

[0033] Figure 6 This is a schematic diagram of the flow system structure of the tester of a turbine blade thermomechanical fatigue testing device under rotating environment according to the present invention;

[0034] Figure 7 This is a schematic diagram of the rotor system of a tester for a turbine blade thermomechanical fatigue testing device under rotating conditions, according to the present invention.

[0035] Figure 8 This is a schematic diagram of the stator system of a test apparatus for thermomechanical combined fatigue testing of turbine blades under rotating conditions, according to the present invention.

[0036] Figure 9 This is a schematic diagram of the support system of the test apparatus for a turbine blade thermomechanical fatigue test under rotating conditions according to the present invention;

[0037] Figure 10 This is a schematic diagram of the combustion chamber of a thermomechanical fatigue testing device for turbine blades under rotating conditions, according to the present invention.

[0038] In the diagram: 0-combustion chamber, 1-high temperature gas system, 2-stator system, 3-rotor blade test piece, 4-rotor system, 5-support system, 6-test system. Detailed Implementation

[0039] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0040] Please see Figure 1-9 As shown, the present invention provides a thermomechanical composite fatigue testing device for turbine blades under rotating conditions, including a high-temperature gas system 1, a stator system 2, a rotor system 4, a support system 5, a testing system 6, an auxiliary system, and a turbine rotor blade test piece 3. The high-temperature gas system 1 is used to provide a gas environment for the turbine rotor blade test piece 3 and control the high and low temperature circulation state of the gas. Its front end is provided with a combustion chamber 0, which is equipped with a dual oil circuit nozzle, and its rear end is provided with a gas flow system. The gas flow system is designed with a blade cascade structure according to the geometry of the turbine rotor blade, and a spray cooling section is provided at the rear of the test section.

[0041] The stator system 2 is designed in conjunction with the rotor system 4, and is divided into multiple chambers, including a gas sealing chamber, an axial force adjustment chamber and a fulcrum sealing chamber. The gas sealing chamber is vented with room temperature high-pressure air to seal the gas from leaking into the chamber. The axial force adjustment chamber is vented with room temperature high-pressure air to adjust the aerodynamic force acting on the rotating disk. The fulcrum sealing chamber is used to suppress the leakage of lubricating oil from the fulcrum bearing. At the same time, the stator system 2 works in conjunction with the determined turbine rotor blade test piece 3 to control the blade tip clearance.

[0042] The rotor system 4 includes a shaft system and a rotating disk. The rotating disk is connected to the shaft system through a clamping structure. The end of the shaft system is connected to a high-speed variable frequency motor. The high-speed variable frequency motor is used to control the rotational speed of the shaft system, thereby realizing the control of the centrifugal force on the turbine rotor blade test piece 3.

[0043] The support system 5 is used to support the entire test apparatus and takes into account the expansion and deformation caused by the temperature of the rotating and stationary systems. The test system 6 includes rotating system test equipment and stationary system test equipment. The rotating system test equipment includes slip ring actuators and dynamic pressure sensors. The stationary system test equipment includes thermocouples, pressure transmitters, and flow meters, which are used to test relevant parameters during the test. The auxiliary system includes a control system, a circulating water system, a fuel system, and an exhaust muffler tower, which are used to cooperate with the upper system.

[0044] Combustion chamber 0 is a series design with design temperatures including 1000K, 1600K, and 1800K. The corresponding combustion chamber 0 is selected according to the specific test requirements.

[0045] The auxiliary fuel supply circuit of the dual fuel line nozzle uses an auxiliary fuel pump whose speed is controlled by a variable frequency motor to provide continuous regulation capability. It is also controlled by a solenoid valve to increase the fuel pressure to a level greater than the mainstream pressure before providing ignition fuel. The main fuel supply circuit uses a regulating valve instead of a solenoid valve. The high-temperature maintenance temperature level of the gas is determined by the fuel pump speed and the stroke opening of the regulating valve. The regulating valve can control the stroke cycle of the regulating valve, so that the transition period time from low temperature to high temperature and from high temperature to low temperature is independently controllable.

[0046] The gas flow system consists of 3-5 blades. The turbine rotor blade test piece is located in the middle of the blade cascade. The gas flow system is designed according to the flow field design requirements of the test blade, and the blade tip clearance, inlet angle, and exhaust angle parameters are matched. Temperature and pressure test parameter interfaces are provided in the inlet section of the test section, and exhaust test parameter interfaces are provided in the exhaust section.

[0047] There are two design options for the rotating disk. Option 1 uses metal materials, taking into account both edge cooling and strength reserves under centrifugal loads. Option 2 uses composite materials, specifically CMC materials, which utilize their temperature resistance to optimize the structural design. The diameter of the rotating disk meets the requirements of the rotor test blades, and the strength of the rotating disk meets the requirements for high temperature and high speed, while also having a certain strength reserve.

[0048] The shaft system is designed with a fulcrum at a suitable position, and the shaft system is designed with grating teeth and boss structures to meet the sealing and positioning design requirements. The specific structure of the shaft system is determined according to the size of the rotating disk and the speed requirements.

[0049] High-speed variable frequency motors achieve adjustable and controllable centrifugal mechanical loads by controlling the frequency conversion time between high and low speeds;

[0050] The testing system 6 can also use infrared thermal imagers and wall temperature couplers as testing instruments, depending on the test conditions and the specific circumstances of the test pieces.

[0051] The high-temperature gas system 1 works in conjunction with the rotor system 4 to achieve synchronous loading of centrifugal force and thermal load. The centrifugal force is controlled by the rotation speed, and the thermal load is controlled by the gas temperature.

[0052] The composite load spectrum is divided into four stages: "heating loading (t1) - high temperature load maintenance (t2) - cooling unloading (t3) - low temperature load maintenance (t4)". The load size, rate and time are adjusted according to the mission requirements.

[0053] In this invention, the high-speed rotation of the rotating components is directly driven by a power unit, causing the turbine rotor blades to generate a realistic and uniformly distributed centrifugal stress field. This provides the most realistic stress field, upon which a thermal load is superimposed, ensuring that the stress state of the rotor blades is highly consistent with the actual working state. Under high-temperature conditions, the centrifugal force generated by high-speed rotation achieves synchronous loading of centrifugal force and thermal load. The centrifugal force is controlled by the rotation speed, and the thermal load is controlled by the gas temperature. The composite load spectrum is typically divided into four stages: "heating loading (t1) - high-temperature load maintenance (t2) - cooling unloading (t3) - low-temperature load maintenance (t4)". The load magnitude, rate, and time can be adjusted according to the task requirements.

[0054] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described or explained in this invention are implemented according to conventional methods in the art unless otherwise specified or limited.

Claims

1. A thermomechanical combined fatigue testing device for turbine blades under rotating conditions, characterized in that: The system includes a high-temperature gas system (1), a stator system (2), a rotor system (4), a support system (5), a testing system (6), an auxiliary system, and a turbine rotor blade test piece (3). The high-temperature gas system (1) is used to provide a gas environment for the turbine rotor blade test piece (3) and control the high and low temperature circulation state of the gas. Its front end is equipped with a combustion chamber (0), which is equipped with a dual oil circuit nozzle. Its rear end is equipped with a gas flow system. The gas flow system is designed with a blade cascade structure according to the geometry of the turbine rotor blade, and a spray cooling section is provided at the rear of the test section. The stator system (2) is designed in conjunction with the rotor system (4) to form multiple chambers, including a gas sealing chamber, an axial force adjustment chamber and a fulcrum sealing chamber. The gas sealing chamber is supplied with room temperature high-pressure air to seal the gas from leaking into the chamber. The axial force adjustment chamber is supplied with room temperature high-pressure air to adjust the aerodynamic force acting on the rotating disk. The fulcrum sealing chamber is used to suppress the leakage of lubricating oil from the fulcrum bearing. At the same time, the stator system (2) works in conjunction with the determined turbine rotor blade test piece (3) to control the blade tip clearance. The rotor system (4) includes a shaft system and a rotating disk. The rotating disk is connected to the shaft system through a clamping structure. The end of the shaft system is connected to a high-speed variable frequency motor. The high-speed variable frequency motor is used to control the rotational speed of the shaft system, thereby realizing the control of the centrifugal force on the turbine rotor blade test piece (3). The support system (5) is used to support the entire test equipment and takes into account the expansion and deformation caused by the temperature of the rotating and stationary systems. The test system (6) includes a rotating system test equipment and a stationary system test equipment. The rotating system test equipment includes a slip ring actuator and a dynamic pressure sensor. The stationary system test equipment includes a thermocouple, a pressure transmitter, and a flow meter. It is used to test relevant parameters during the test. The auxiliary system includes a control system, a circulating water system, a fuel system, and an exhaust muffler tower. It is used to cooperate with the above systems. The test system (6) also tests the composite load spectrum.

2. The thermomechanical combined fatigue testing equipment for turbine blades under rotating conditions according to claim 1, characterized in that: The combustion chamber (0) is designed in a series, with design temperatures including 1000K, 1600K, and 1800K. The corresponding combustion chamber (0) is selected according to the specific requirements of the test.

3. The thermomechanical combined fatigue testing equipment for turbine blades under rotating conditions according to claim 2, characterized in that: The auxiliary oil nozzle supply circuit of the dual-oil-circuit nozzle uses an auxiliary oil pump whose speed is controlled by a variable frequency motor to provide continuous adjustment capability, and is controlled by a solenoid valve to increase the oil pressure to a level greater than the mainstream pressure before providing ignition fuel for ignition. The main oil nozzle supply circuit uses a regulating valve instead of a solenoid valve. The high-temperature maintenance temperature level of the gas is determined by the oil pump speed and the stroke opening of the regulating valve. The regulating valve can control the stroke cycle of the regulating valve, so that the transition period time from low temperature to high temperature and from high temperature to low temperature is independently controllable.

4. The thermomechanical combined fatigue testing equipment for turbine blades under rotating conditions according to claim 3, characterized in that: The gas flow system consists of 3-5 blades. The turbine rotor blade test piece is located in the middle of the blade cascade. The gas flow system is designed with blade tip clearance, inlet angle and exhaust angle parameters matched according to the flow field design requirements of the test blade. Temperature and pressure test parameter interfaces are provided in the inlet section of the test section, and exhaust test parameter interfaces are provided in the exhaust section.

5. The thermomechanical combined fatigue testing equipment for turbine blades under rotating conditions according to claim 4, characterized in that: The design scheme of the rotating disk includes two options. Option 1 uses metal materials, taking into account the cooling of the disk edge and the strength reserve under centrifugal load. Option 2 uses composite materials, specifically CMC materials, which utilize their temperature resistance to optimize the structural design. The diameter of the rotating disk meets the requirements of the rotor test blades, and the strength of the rotating disk meets the requirements of high temperature and high speed, while also having a certain strength reserve.

6. The thermomechanical combined fatigue testing equipment for turbine blades under rotating conditions according to claim 5, characterized in that: The shaft system is designed with a fulcrum at a suitable position, and the shaft system is designed with grating teeth and boss structures to meet the sealing and positioning design requirements. The specific structure of the shaft system is determined according to the size of the rotating disk and the speed requirements.

7. The thermomechanical combined fatigue testing equipment for turbine blades under rotating conditions according to claim 6, characterized in that: The high-speed variable frequency motor achieves adjustable and controllable centrifugal mechanical load by controlling the frequency conversion time between high and low speeds.

8. The thermomechanical combined fatigue testing equipment for turbine blades under rotating conditions according to claim 7, characterized in that: The test system (6) can also use infrared thermal imagers and wall temperature couplers as test instruments according to the test status and specific conditions of the test pieces.

9. The thermomechanical combined fatigue testing equipment for turbine blades under rotating conditions according to claim 8, characterized in that: The high-temperature gas system (1) works in conjunction with the rotor system (4) to achieve synchronous loading of centrifugal force and thermal load. The centrifugal force is controlled by the rotation speed, and the thermal load is controlled by the gas temperature.

10. The thermomechanical combined fatigue testing equipment for turbine blades under rotating conditions according to claim 9, characterized in that: The composite load spectrum is divided into four stages: "heating loading (t1) - high temperature load maintenance (t2) - cooling unloading (t3) - low temperature load maintenance (t4)". The load size, rate and time are adjusted according to the task requirements.

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