A thermal fatigue testing system and method for an aero-engine casing

Abstract

A thermal fatigue testing system for an aero-engine casing includes an intake section, a test section, and an exhaust section. The test section includes a parallel gas storage path and a pressurization path. The casing specimen is placed on the pressurization path. During the test load holding phase, the compressed gas input is stored in a storage tank in the gas storage path and used to cool the high-temperature gas discharged from the casing. The pressurization path includes a heating path, and the temperature load on the input casing specimen is adjusted by controlling the flow rate and velocity of the heating path. A thermal fatigue testing method for an aero-engine casing allows the air compressor unit to operate continuously without shutdown during the test, saving equipment time and lifespan, enhancing the reliability of the test system, and fully utilizing the compressed gas in the pipeline, thus saving energy.

Description

Technical Field

[0001] This invention relates to the field of aero-engines, and more specifically to an aero-engine casing hot-compression fatigue testing system and a testing method. Background Technology

[0002] The pressure casing of an engine is a critical life-limited component in civil aircraft engines. During engine airworthiness certification, rigorous testing and verification are required according to airworthiness regulations, necessitating strict life-limited component management. Therefore, for pressure casings, improving fatigue testing equipment and techniques under high-temperature and high-pressure environments is a crucial issue in the development of civil aircraft engines.

[0003] Currently, the common technique for hot-compression fatigue testing of pressure chambers involves filling the chamber with compressed hot air to simultaneously apply temperature and pressure loads. During the test, the temperature and pressure of the input air are adjusted to achieve cyclic loading. Hot-compression fatigue testing of pressure chambers has a long test cycle, exceeding 18,000 cycles, with continuous equipment operation approaching one year, placing high demands on the efficiency and reliability of the testing equipment. Existing technologies mainly suffer from the following problems: slow temperature load application, resulting in low test efficiency; interruption of load input by shutting down the air compressor during the pressure holding phase of the chamber, causing repeated start-ups and shutdowns of the unit, severely damaging the lifespan of the air compressor and posing a threat to the reliability of the test system; frequent venting of compressed air upstream of the chamber specimen, resulting in energy waste; and the use of heaters and temperature sensors to control the temperature load input, but in high-cycle testing, insufficient stability of the heaters and temperature sensors leads to inaccurate temperature control, thus affecting the reliability of the hot-compression fatigue test results. Summary of the Invention

[0004] This invention provides a pressure-bearing casing hot-pressure fatigue testing device and method, aiming to improve the reliability of the device during the test, save the device life, reduce the test energy consumption, and improve the temperature load control method.

[0005] According to one aspect of the present invention, a thermal fatigue testing system for an aero-engine casing is provided, comprising an intake section, a test section, and an exhaust section connected in sequence, wherein:

[0006] The test section includes a pressurized air path and a storage air path connected in parallel. The pressurized air path is used to deliver pressure loads to the casing test piece, which is placed on the pressurized air path. The storage air path includes a storage valve group and a storage tank. The storage valve group includes a storage control valve group, which controls the opening and closing of the inlet and outlet ends of the storage air path. The exhaust section includes a mixer, and the pressurized air path and the storage air path are connected to the mixer to allow the high-temperature gas from the pressurized air path to mix and cool with the gas from the storage air path within the mixer. During the load holding phase, the pressurized air path is closed, and the air compressor of the test system remains operational, storing the input air in the storage tank for cooling the exhaust and protecting the valve groups of subsequent equipment. This avoids repeated switching of the air compressor unit, which reduces its service life, and fully utilizes the compressed air in the pipeline, achieving the effects of improving system reliability and energy saving and environmental protection.

[0007] According to one embodiment of the present invention, the pressurized gas path further includes a heating electric valve and an electric heater. The heating electric valve and the electric heater form a heating gas path, which is connected in series on the air inlet side of the casing test piece, for outputting heated and pressurized gas to the casing to apply temperature and pressure loads.

[0008] Preferably, the electric heater outputs a preset fixed power, and the electric heating valve and the electric heater form a heating gas path. Multiple sets of parallel heating gas paths are connected in series on the air inlet side of the casing specimen.

[0009] Preferably, the heating electric valve is configured as a temperature control device for the pressurized gas path, adjusting the opening and closing of the heating electric valve to regulate the inlet flow rate and velocity of the heating gas path, thereby regulating the temperature of the gas input to the casing specimen.

[0010] When all the heating gas circuits' electric valves and electric heaters are opened, the test system outputs the highest gas temperature; closing some of the heating gas circuits increases the gas flow rate and velocity in the remaining heating gas circuits, resulting in a decrease in the output gas temperature. This process eliminates the need to adjust the electric heater's output power, simplifying setup, maintaining a large intake volume during loading, and improving temperature loading efficiency.

[0011] Preferably, the gas storage circuit of the test system also includes a pressure relief valve, which is used to discharge excess gas when the pressure of the gas storage tank reaches the upper limit, thereby further improving the safety of the system.

[0012] Preferably, the test system is equipped with multiple one-way valve groups. The one-way valve groups restrict the airflow in the system to flow in the direction of the inlet section, test section and exhaust section. At the same time, the airflow in each section of the system is also restricted to flow in one direction to avoid backflow of gas causing equipment damage or affecting the test accuracy.

[0013] According to another aspect of the present invention, a method for hot-compression fatigue testing of an aero-engine casing is provided. The method includes a preheating stage and a cyclic loading test stage. Each cycle of the cyclic loading test stage includes a peak loading stage, a peak load holding stage, a trough loading stage, and a trough load holding stage. The test system used in the method includes a working fluid storage device for storing the working fluid input to the system during the peak load holding stage and the trough load holding stage. The test method includes a preheating stage, a peak loading stage, a peak load holding stage, a trough loading stage, and a trough load holding stage.

[0014] The preheating phase involves preheating the casing specimen. During the peak loading phase, after the casing specimen has been preheated to a predetermined temperature, it is heated to a preset peak temperature, and a pressure working fluid is input to complete the peak pressure loading. Simultaneously, the pressure working fluid stored in the working fluid storage device from the previous cycle is mixed with the high-temperature working fluid discharged from the casing specimen for cooling. During the peak load maintenance phase, the supply of pressure working fluid to the casing specimen is stopped, maintaining the peak temperature and pressure load. Simultaneously, the pressure working fluid input by the test system is stored in the working fluid storage device. During the trough loading phase, after the casing specimen completes the peak load maintenance, the high-temperature pressure working fluid is discharged, and the temperature and pressure load of the casing specimen are adjusted to a preset trough value. Simultaneously, the pressure working fluid stored in the working fluid storage device during the peak load maintenance phase is mixed with the high-temperature working fluid discharged from the casing specimen for cooling. During the valley load maintenance phase, the supply of pressure working fluid to the casing specimen is stopped, and the casing specimen is maintained at the valley load of temperature and pressure. At the same time, the pressure working fluid input by the test system is stored in the working fluid storage device.

[0015] After the casing specimen completes the valley load holding phase, the next cycle begins from the peak load phase. From the preheating phase to the end of the test, the pressure working fluid input device of the test system operates continuously without interruption, in order to save equipment time and lifespan and improve the reliability of the test system.

[0016] According to one embodiment, in the test method, the working medium is air, and the heating method is to input hot air into the casing test piece.

[0017] According to another embodiment, the test system used in the test method includes a heating device, and different heating temperatures are achieved by adjusting the air flow rate through the heating device.

[0018] Preferably, the test system has a constant flow rate of air intake and includes multiple sets of parallel heating air paths. The heating device is respectively installed in each heating air path. The method of adjusting the air flow rate and velocity through the heating device is to control the number of heating air paths connected, so as to make the temperature loading mode more flexible, maintain a large flow rate of air intake in the system, and improve the test efficiency. Attached Figure Description

[0019] Figure 1 A schematic diagram of the thermal fatigue testing system for an aero-engine casing.

[0020] Figure 2 A schematic diagram of another embodiment of the aircraft engine casing hot-compression fatigue testing system;

[0021] Figure 3 Flowchart of the hot-compression fatigue test method for aero-engine casing;

[0022] Figure 4 A schematic diagram of the preheating stage of an aero-engine casing hot-press fatigue test system;

[0023] Figure 5 A schematic diagram of the peak loading stage of an aero-engine casing hot-compression fatigue test system;

[0024] Figure 6 A schematic diagram of the peak load holding stage of an aero-engine casing hot-compression fatigue test system;

[0025] Figure 7 A schematic diagram of the loading trough stage of the thermal fatigue test system for aero-engine casing;

[0026] Figure 8 A schematic diagram of the valley load holding phase of the thermal fatigue test system for aero-engine casing.

[0027] Meaning of reference numerals in the attached diagram:

[0028] 1-Air compressor unit; 2-Dryer; 3-Filter; 4-Pressure stabilizing tank; 5-Inlet section valve; 6-Heating electric valve; 7-Electric heater; 8-Inlet switch valve; 9-Inlet regulating valve; 10-Casing test piece; 11-Mixer; 12-Exhaust regulating valve; 13-Exhaust check valve; 14-Exhaust silencer; 15-Storage inlet valve; 16-Storage tank; 17-Flow meter; 18-Storage exhaust valve; 19-Storage check valve; 20-Electric heater; 21-Inlet section; 22-Pressurized air circuit; 23-Storage air circuit; 24-Exhaust section.

[0029] The above figures are only used to describe the technical information of the present invention and do not constitute a limitation on the embodiments of the present invention. Detailed Implementation

[0030] The following description, in conjunction with the accompanying drawings and embodiments, further illustrates the thermal fatigue testing system and method for aero-engine casings.

[0031] According to one aspect of the embodiments of the present invention, such as Figure 1 As shown, the aero-engine casing hot-pressure fatigue test system includes an intake section 21, a test section, and an exhaust section 24, wherein the test section includes a pressurized air passage 22 and a storage air passage 23.

[0032] The intake section 21 includes an air compressor unit 1, a dryer 2, a filter 3, a pressure stabilizing tank 4, and an intake section valve 5. The air compressor unit 1 is used to provide a high-pressure airflow to the test system, and the pressure stabilizing tank 4 and the intake section valve are used to ensure the stability of the flow rate and pressure of the input gas.

[0033] The pressurized air path 22 and the storage air path 23 in the test section are connected in parallel. The pressurized air path 22 includes three sets of heating air paths a, b, and c connected in parallel, and an intake switch valve 8, an intake regulating valve 9, and a casing specimen 10 connected in series with them. Each heating air path includes its own electric heating valve 6 and electric heater 7. According to different test operation procedures, the compressed air input from the intake section 21 enters the pressurized air path 22, is heated by one or more heating air paths, and is delivered to the casing specimen 10 through the intake switch valve 8 and the intake regulating valve 9 to apply temperature and pressure loads. The air storage passage 23 includes an air storage inlet valve 15, an air storage tank 16, a flow meter 17, an air storage exhaust valve 18, and an air storage check valve 19. It is used to store the compressed air input from the air inlet section during the test load holding phase to achieve continuous operation of the air compressor unit 1. At the same time, it is used to store the compressed air output from the air compressor unit 1 to prevent the system from being damaged by sudden stop when the pressurization passage 22 fails and needs to stop air supply. The pressurization passage 22 and the air storage passage 23 are connected in parallel after the air inlet section 21 to form the test section of the test system for carrying out hot pressure fatigue tests.

[0034] The exhaust section 24 is connected after the test section and includes a mixer 11, an exhaust regulating valve 12, an exhaust check valve 13, and an exhaust silencer 14 connected in sequence. The mixer 11 is connected to the test pressurization gas line 22 and the storage gas line 23, allowing the gas discharged from the casing 10 and the gas stored in the storage tank 16 to enter, so as to mix and cool the high-temperature gas discharged from the casing with the gas in the storage gas line, reduce the temperature of the gas discharged from the test system, and protect the subsequent test pipelines and valve groups.

[0035] The gas storage check valve 19 and the exhaust check valve 13 in the test system are used to ensure unidirectional gas flow in the pipeline. The gas storage check valve 19 is used to prevent gas in the mixer 11 from flowing back into the gas storage passage 23, avoiding damage to the pipeline and valve assembly by high-temperature gas; the exhaust check valve 13 is used to prevent gas outside the system from flowing back into the gas through the exhaust section 24, avoiding interference with the test results and damage to the valve assembly.

[0036] According to another embodiment, the gas storage path 23 also includes a pressure limiting valve. The capacity of the gas storage tank 16 is designed to be the total amount of gas input into the intake section during one load-carrying phase in a single cycle. The pressure limiting valve is used to prevent the gas stored in the gas storage tank 16 from exceeding its capacity limit and causing safety hazards due to the accumulation of system errors after multiple cycles. When the gas storage tank 16 is full, the excess gas is discharged through the pressure limiting valve.

[0037] According to yet another embodiment, such as Figure 2 As shown, the test system omits the heating gas path in the pressurized gas path 22, and instead provides multiple evenly distributed electric heaters 20 on the wall of the casing test piece 10. The electric heaters 20 are used to directly heat the casing test piece 10 to achieve the preset test temperature.

[0038] According to another aspect of the embodiments of the present invention, such as Figure 3 As shown, the test method for the thermal fatigue test of an aero-engine casing includes a preheating stage and a cyclic loading test stage. Each round of the cyclic loading test stage includes a peak loading stage, a peak load holding stage, a load trough stage, and a trough load holding stage. At the start of the test, the intake valve 5 is opened, the air compressor unit 1 starts operating, and supplies air to the test section at a constant air flow rate m. The air storage tank 16 has already stored a certain amount of compressed air. In this embodiment, the temperature difference between the peak temperature load and the input compressed air is T1, and the temperature difference between the trough temperature load and the input compressed air is T2. The test is set to T1:T2 = 3:2. The specific heat capacity of air is C, so the power selected for each of the three electric heaters 7 is W = 1 / 3 mCT1. The test is carried out according to the following steps:

[0039] During the preheating stage, the airflow path is as follows: Figure 4 As indicated by the arrows in the diagram. Of the three sets of heating gas paths, set a is open, while sets b and c are closed; the gas storage inlet valve 15 is closed, and the gas storage exhaust valve 18 is closed; the exhaust regulating valve 12 is open. All gas flow passes through one heating gas path, with a high flow rate and low temperature, completing the preheating of the casing specimen 10 and the test system piping.

[0040] During the peak loading phase, the airflow path is as follows: Figure 5 As indicated by the arrows in the diagram, all three sets of heating gas paths, consisting of the electric heating valve 6 and the electric heater 7, are open; the gas storage inlet valve 15 is closed, the gas storage exhaust valve 18 is open, and the exhaust regulating valve 12 is open. The airflow passes through the three heating gas paths at a low velocity and high temperature. The electric heater heats the air to T1 according to a preset power, raising it to the temperature defined by the peak load, thus completing the peak temperature loading on the casing specimen 10. The high-temperature air discharged from the casing specimen 10 is mixed with the low-temperature air from the gas storage path in the mixer 11 to cool it down, and finally discharged from the test system through the exhaust section. Subsequently, the exhaust regulating valve 12 is adjusted to a suitable opening to reduce exhaust, causing the pressure inside the casing specimen 10 to increase, completing the peak pressure loading.

[0041] During the peak load maintenance phase, the airflow path is as follows: Figure 6 As indicated by the arrows in the diagram. Heating electric valve 6 and electric heater 7 are both closed; gas inlet valve 15 is open, gas outlet valve 18 is closed; exhaust regulating valve 12 is closed. The casing test piece 10 is subjected to load maintenance at peak temperature and peak pressure, while all compressed air from the inlet section is stored in the gas tank 16.

[0042] During the loading trough phase, the airflow path is as follows: Figure 7 As indicated by the arrows in the diagram. Of the three sets of heating gas paths consisting of the electric heating valve 6 and the electric heater 7, sets a and b are open, and set c is closed; the gas storage inlet valve 15 is closed, and the gas storage exhaust valve 18 is open; the exhaust regulating valve 12 is open. The high-temperature gas in the casing specimen 10 is discharged, and the pressure decreases to the lowest possible value. The high-temperature gas is then mixed with the low-temperature air from the gas storage path in the mixer 11 for further cooling, and finally discharged through the exhaust section. At this time, the air in the inlet section passes through two heating gas paths, resulting in a higher flow rate and lower temperature, gradually reducing the casing specimen 10 to the lowest possible temperature T2.

[0043] During the valley load maintenance phase, the airflow path is as follows: Figure 8 As indicated by the arrows in the diagram. Heating electric valve 6 and electric heater 7 are both closed, air inlet valve 15 is open, air outlet valve 18 is closed; exhaust regulating valve 12 is closed. The casing test piece 10 is kept under load at valley temperature and valley pressure, while all compressed air from the intake section is stored in the air tank 16.

[0044] After the valley load is maintained, the next cycle of loading begins from the peak load stage until the test ends. Throughout the entire test, air compressor unit 1 remains running without interruption, avoiding the wear and tear on the equipment's lifespan caused by frequent start-ups and shutdowns, reducing the risk of test system failure, and improving the reliability of the test system.

[0045] According to another embodiment, the pressure working fluid used in the test method is simulated exhaust gas with reference to the gas composition produced by the combustion of an aero-engine.

[0046] According to another embodiment, the power of the electric heaters 7 installed in heating gas paths a, b, and c are calculated as W1, W2, and W3, respectively, based on the heating temperatures required for different stages of the experimental design. During the preheating stage, the electric heating valve 6 and electric heater 7 of heating gas path c are turned on to preheat the system with power W3. During the peak loading stage, the electric heating valves 6 and electric heaters 7 of heating gas paths a, b, and c are turned on to load the peak temperature. During the valley loading stage, the electric heating valves 6 and electric heaters 7 of heating gas paths a and c are turned off, and the electric heating valve 6 and electric heater 7 of heating gas path b are turned on to load the valley temperature with power W2.

[0047] According to another embodiment, the total intake air volume of the test system is constant at m, the preheating temperature is T0 compared to the temperature difference between the input compressed air and the preheating temperature, the peak temperature load is T1 compared to the temperature difference between the input compressed air and the temperature difference between the valley temperature load and the temperature difference between the input compressed air and the temperature difference between the valley temperature load and the temperature difference between the input compressed air and the temperature difference between the peak temperature load and the temperature difference between the peak temperature load and the temperature difference between the peak temperature load and the temperature difference between the peak temperature load and the temperature difference load. The electric heaters 7 of the heating air paths a, b, and c correspond to power values ​​W1, W2, and W3, respectively. By setting appropriate power values ​​for W1, W2, and W3, the preset test process can be achieved. The calculation method for W1, W2, and W3 is as follows:

[0048] W1=mCT0, W2=mC(T1-T0-T2), W3=mCT2.

[0049] It should be understood that the above embodiments are used to describe the present invention in more detail so that those skilled in the art can understand it, and do not constitute a limitation on the implementation and protection scope of the present invention. Within the protection scope of the present invention, the structure of the experimental system involved in the present invention can be modified or replaced with equivalent parts, and the steps of the designed experimental method can also be modified using equivalent methods, all of which fall within the protection scope of the present invention.

Claims

1. A thermal fatigue testing system for an aircraft engine casing, comprising an intake section, a test section, and an exhaust section connected in sequence, characterized in that: The test section includes a pressurized gas path and a gas storage gas path, wherein the pressurized gas path and the gas storage gas path are connected in parallel. The pressurized air path is used to deliver a pressure load to the casing test piece, and the casing test piece is disposed on the pressurized air path; The gas storage circuit includes a gas storage valve group and a gas storage tank. The gas storage valve group includes a gas storage control valve group, which controls the opening and closing of the gas inlet and outlet of the gas storage circuit respectively. The exhaust section includes a mixer, and the pressurized gas path and the gas storage path are connected to the mixer to allow the high-temperature gas from the pressurized gas path to be mixed and cooled with the gas from the gas storage path within the mixer.

2. The aero-engine casing hot-compression fatigue testing system according to claim 1, characterized in that, The pressurized gas path also includes a heating gas path consisting of a heating electric valve and an electric heater. The heating gas path is connected in series on the air inlet side of the casing test piece and is used to apply a temperature load to the casing test piece.

3. The aero-engine casing hot-compression fatigue testing system according to claim 2, characterized in that, The electric heater outputs a preset fixed power, and the pressurized gas path includes multiple parallel heating gas paths.

4. The aero-engine casing hot-compression fatigue testing system according to claim 3, characterized in that, The heating electric valve is configured as a temperature control device for the pressurized gas path. By adjusting the opening and closing of the heating electric valve, the inlet flow rate and velocity of the heating gas path are adjusted, thereby controlling the temperature of the gas input to the casing specimen.

5. The aero-engine casing hot-compression fatigue testing system according to claim 1, characterized in that, The gas storage circuit also includes a pressure relief valve, which discharges excess gas when the gas storage tank reaches its pressure limit.

6. The aero-engine casing hot-compression fatigue testing system according to claim 1, characterized in that, It also includes multiple one-way valve assemblies, which restrict the airflow within the system to flow in the directions of the intake section, test section, and exhaust section, and the airflow within each section of the system is also unidirectional.

7. A method for hot-compression fatigue testing of an aero-engine casing, comprising a preheating stage and a cyclic loading test stage, wherein each cycle of the cyclic loading test stage includes a peak loading stage, a peak load holding stage, a load trough stage, and a trough load holding stage, characterized in that: The test method includes: A testing system is provided, which includes a pressure working fluid input device and a working fluid storage device; During the preheating stage, the casing test piece is preheated; During the peak loading stage, after preheating, the casing specimen is heated to a preset peak temperature, and a pressure working medium is input into the casing specimen using a pressure working medium input device to complete the peak pressure loading. During the peak pressure loading process, the working medium stored in the working medium storage device is mixed with the high-temperature working medium discharged from the casing specimen for cooling. During the peak load maintenance phase, the supply of pressure working fluid to the casing specimen is stopped, and the peak load of temperature and pressure of the casing specimen is maintained. At the same time, the pressure working fluid output by the pressure working fluid input device is stored in the working fluid storage device. During the loading trough phase, after the peak load is maintained, the high-temperature and high-pressure working fluid is discharged from the casing specimen. The temperature and pressure load of the casing specimen are adjusted to the preset trough value. At the same time, the pressure working fluid in the working fluid storage device is mixed with the high-temperature working fluid discharged from the casing specimen for cooling. During the valley load maintenance phase, the supply of pressure working fluid to the casing specimen is stopped, and the temperature and pressure of the casing specimen are maintained at the preset valley value. At the same time, the pressure working fluid output by the pressure working fluid input device is stored in the working fluid storage device. After completing the valley load maintenance phase, the next cycle begins from the peak load phase; From the start of the preheating phase to the end of the test, the pressure working fluid input device operates continuously without interruption.

8. The method for hot-compression fatigue testing of an aero-engine casing according to claim 7, characterized in that, The working medium is air. In each cycle, the temperature and pressure of the casing test piece are applied by inputting hot air into the casing test piece.

9. The method for hot-compression fatigue testing of an aero-engine casing according to claim 8, characterized in that, The test system includes a heating device, and the method for adjusting the temperature loading of the casing specimen includes adjusting the airflow and velocity through the heating device to achieve different temperatures on the casing specimen.

10. The method for hot-compression fatigue testing of an aero-engine casing according to claim 9, characterized in that, The test system has a constant air intake and includes multiple sets of parallel heating air paths. Each heating air path is equipped with a heating device. The method for adjusting the air flow rate and velocity through the heating device is to control the number of heating air paths that are connected.

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