Thermal fatigue test system and method for testing thermal shock resistance of stealth coating

Abstract

The invention provides a thermal fatigue test system and method for testing thermal shock resistance of a stealth coating, and belongs to the technical field of aero-engine tests.The system comprises a switching section used for introducing main runner gas and measuring the state of the main runner gas; the exhaust section is used for exhausting gas in the main runner and cooling the gas; the test cascade comprises a test piece and a container device wrapping the test piece, the front end of the container device is connected with the switching section, the rear end of the container device is connected with the exhaust section, and the test piece is inserted into the container device; the cooling air system comprises a compressed air control system and an electric heater, the compressed air control system comprises a flowmeter, a three-way valve and an exhaust regulating valve, the flowmeter is arranged at the front end of the electric heater, the rear end of the electric heater is connected with an inlet of the three-way valve, one outlet of the three-way valve is connected to an inlet of the test piece, and the other outlet is connected with the exhaust regulating valve for exhausting; and the test and data acquisition system comprises a temperature measuring instrument, a pressure scanning valve and kingview software.

Description

Technical Field

[0001] This application belongs to the field of aero-engine testing technology, and specifically relates to a thermal fatigue testing system and method for testing the thermal shock resistance of stealth coatings. Background Technology

[0002] A certain type of engine is equipped with a composite support plate with metal edges that acts as a radar absorber. To reduce the scattering effect of the metal edges within the cavity, stealth measures are required for the metal edges, namely, spraying a radar-absorbing coating onto the surface of the metal edges. This engine uses the fifth stage compressed air from the high-pressure compressor for bleed air anti-icing at the engine inlet. During the development of the radar absorber, the anti-icing temperature of various parts of the radar absorber was measured. The measurement results show that the temperature of the air collection box at the inlet end of the radar absorber's metal edge reaches as high as 400℃. After being cooled by the main flow through the internal channel of the metal edge, the temperature of the hot air reaching the cap at the outlet end of the metal edge is 260℃. The change in the internal hot air temperature of the radar absorber's metal edge alters the temperature and thermal stress levels of the surface coating, potentially leading to thermal fatigue. In severe cases, this can cause the coating to break off, resulting in the radar absorber losing its stealth function.

[0003] Therefore, it is essential to conduct thermal fatigue tests on the stealth coating of the metal edge of the composite support plate.

[0004] Similar to turbine blades, composite support plates are hollow structures. Therefore, a thermal fatigue testing system based on turbine blade thermal fatigue testing is considered for their application. However, this system creates a combustion chamber-based hot gas flow environment, with each test cycle consisting of four phases: heating, high-temperature holding, cooling, and low-temperature holding. During the heating cycle, the hot gas flow temperature is increased, enveloping the turbine blade components in heat. During the cooling cycle, the hot gas flow temperature is decreased while cold air or water is introduced into the combustion gas for cooling. The turbine blade surface temperature is affected by the heating and cooling of the combustion gas, resulting in thermal fatigue. In this test, the temperature cycle only changes the external combustion gas temperature of the turbine blade, not the internal cooling air temperature. Therefore, this method is not suitable for the working environment of wave-absorbing and fluid-conducting stealth coatings. Thus, a thermal fatigue testing system and method capable of simulating the real working environment of stealth coatings is needed. Summary of the Invention

[0005] The purpose of this application is to provide a thermal fatigue testing system and method for testing the thermal shock resistance of stealth coatings, in order to solve or mitigate at least one of the problems in the background art.

[0006] The technical solution of this application is: a thermal fatigue testing system for testing the thermal shock resistance of stealth coatings, comprising:

[0007] The transition section is used to introduce the mainstream gas and measure the state of the mainstream gas.

[0008] The exhaust section is used to discharge the main gas flow and cool the gas.

[0009] The test blade includes a test specimen and a container device for enclosing the test specimen. The front end of the container device is connected to the transition section, and the rear end of the container device is connected to the exhaust section. The test specimen is inserted into the container device.

[0010] A cooling air system includes a compressed air control system and an electric heater. The compressed air control system includes a flow meter, a three-way valve, and an exhaust regulating valve. A flow meter is installed at the front end of the electric heater, and the rear end of the electric heater is connected to the inlet of the three-way valve. One outlet of the three-way valve is connected to the inlet of the test piece, and the other outlet of the three-way valve is connected to the exhaust regulating valve for exhaust.

[0011] The testing and data acquisition system includes a temperature measuring instrument, a pressure scanning valve, and KingSCADA software. The temperature measuring instrument is used to measure the surface wall temperature of the stealth coating, the pressure scanning valve is used to measure the internal pressure of the test piece, and the KingSCADA software is used to monitor and acquire the flow rate, temperature, and pressure of the main airflow, the surface wall temperature of the stealth coating, the flow rate, temperature, and pressure of the cooling air flowing inside the test piece, the test time, the number of cycles, and to control the three-way valve and the exhaust regulating valve.

[0012] In at least one embodiment of this application, the transition section includes an air inlet channel and a test mounting base. The air inlet channel is mounted on the test platform via the test mounting base. The front end of the air inlet channel is connected to the main channel for introducing gas in the main channel into the inlet of the test blade cascade. Temperature probes and pressure probes are installed on the air inlet channel or the test mounting base to detect the state of the gas in the main channel.

[0013] In at least one embodiment of this application, the test blade includes an inlet support plate, an exhaust support plate, a test piece fixing base, a top plate, a side plate, and a mounting plate. The inlet support plate, the exhaust support plate, the test piece fixing base, the top plate, and the side plate constitute a container device for accommodating the test piece. The test piece is mounted on the container device via the mounting plate. The test piece fixing base is provided with an air intake channel. Cooling gas entering from the inlet of the test piece flows along the interior of the test piece to the air intake channel and then flows into the main flow channel from the air intake channel.

[0014] In at least one embodiment of this application, the scheduling section includes an exhaust duct and a cooling section, the exhaust duct being connected to the exhaust support plate of the test blade cascade, and the cooling section being disposed on the rear side of the exhaust duct.

[0015] In at least one embodiment of this application, the three-way valve is a pneumatic three-way valve.

[0016] In at least one embodiment of this application, the exhaust regulating valve is an electromagnetic regulating valve.

[0017] On the other hand, the technical solution provided in this application is: a test method using a thermal fatigue test system for testing the thermal shock resistance of stealth coatings as described above, comprising:

[0018] S10, during the high-temperature test debugging phase, the three-way valve is controlled by the KingSCADA software to connect the first flow path to the test piece. Cooling air enters the test piece through the flow meter, electric heater, and three-way valve. When the wall temperature field requirements of the test piece are met, the cooling air flow rate, temperature, pressure parameters, flow meter reading, electric heater outlet temperature, and cooling air inlet pressure data are obtained.

[0019] S20, during the low-temperature testing and commissioning phase, the three-way valve is controlled by the KingSCADA software to connect the second flow path for discharge. Cooling air flows into the exhaust silencer tower through the flow meter, electric heater, three-way valve, and exhaust regulating valve. By adjusting the opening of the exhaust regulating valve, the cooling air flow rate and the pressure before the valve are kept consistent with those in step S10. The cooling air flow rate, temperature, pressure parameters, and the opening of the exhaust regulating valve are obtained at this time.

[0020] S30. During the formal test, according to the cooling air flow rate, temperature, pressure and the opening of the exhaust regulating valve determined in steps S10 and S20, the duration of cooling air entering and not entering the test piece is determined based on the wall temperature field requirements of the test piece. This determines the switching time of the three-way valve, thereby realizing the thermal shock cycle state of the stealth coating and more accurately assessing the stealth coating's resistance to thermal shock.

[0021] The thermal fatigue test system provided in this application for testing the thermal shock resistance of stealth coatings provides cooling air with periodically changing temperature, realizing flow field simulation of the actual working state of the stealth coating of wave-absorbing fluid. It can more accurately assess the thermal shock resistance of the stealth coating, overcome the shortcomings of traditional electric heaters that cannot "cut off the air" and have large thermal inertia, and realize the rapid "low temperature-high temperature" cycle conversion of the cooling air inside the metal edge of the wave-absorbing fluid. Attached Figure Description

[0022] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0023] Figure 1 This is a schematic diagram of the experimental system of this application.

[0024] Figure 2 This is a partial structural diagram of the test system of this application.

[0025] Figure 3 This is a side view of a portion of the experimental system structure of this application.

[0026] Figure 4 This is a schematic diagram of the cooling air system in this application. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0028] Existing test methods for altering the gas cycle temperature and turbine blade-based test systems are unsuitable for the working environment of wave-absorbing fluid stealth coatings and cannot accurately reflect the thermal fatigue characteristics of wave-absorbing fluid stealth coatings against thermal shock. Furthermore, in existing tests, the cooling air for the test specimen is heated by an electric heater to simulate compressor bleed air. The electric heater requires a continuous flow of air to avoid the risk of fire caused by dry burning. Moreover, the electric heater heats the air through resistance wire, which has high thermal inertia. After power is cut off, it takes a long time for the airflow to cool down. Therefore, if the electric heater is de-energized to reduce the cooling air temperature of the test specimen during the test, a long waiting time is required, which greatly prolongs the test cycle and reduces test efficiency.

[0029] Therefore, this application provides a thermal fatigue test system that can simulate the actual working environment of a wave-absorbing fluid stealth coating, realize the flow field simulation of the actual working state of the wave-absorbing fluid stealth coating, and more accurately assess the thermal shock resistance of the stealth coating; at the same time, it provides a test method that, while ensuring the stable operation of the electric heater, realizes the "low temperature - high temperature" cyclic conversion of the cooling air inside the test piece.

[0030] like Figures 1 to 4 As shown, this application provides a thermal fatigue test system for testing the thermal shock resistance of stealth coatings. It can realize thermal fatigue tests under the real working environment of wave-absorbing and fluid-conducting stealth coatings. The test system 10 includes: a transition section 1, a test blade cascade 2, an exhaust section 3, a cooling air system 4, and a test and data acquisition system 5.

[0031] In this application, the transition section 1 includes an air inlet duct 11 and a test mounting base 12. The air inlet duct 11 is mounted on the test platform or test site ground via the test mounting base 12. The front end of the air inlet duct 11 is connected to the main flow channel (not shown) to introduce the main flow channel gas into the inlet of the test blade cascade 2. Temperature probe 13 and pressure probe 14 are installed on the air inlet duct 11 or the test mounting base 12 to detect the state of the main flow channel gas. In the illustrated embodiment of this application, temperature probe 13 and pressure probe 14 are installed on the air inlet duct 11 near the inlet of the test blade cascade 2.

[0032] In this application, the test blade cascade 2 includes a wave-absorbing and fluid-guiding metal edge test piece 21, a test piece fixing base 22, an air inlet support plate 23, an exhaust support plate 24, a top plate 25, a side plate 26, and a support plate 27, etc. The air inlet support plate 23, the exhaust support plate 24, the test piece fixing base 22, the top plate 25, and the side plate 26 constitute a container device for accommodating the test piece 21. The front end of the air inlet support plate 23 is connected to the air inlet cavity 11 of the transition section 1, and the rear end of the exhaust support plate 24 is connected to the exhaust section 3. The support plate 27 is installed on the upper end of the test piece 21 and inserted into the container device. The test piece fixing base 22 is provided with an air duct 221, and the bottom of the test piece 21 is connected to the air duct 221, so that the cooling gas inside the test piece 21 can be discharged into the main channel. The test blade cascade 2 is used to calibrate the test piece 21 according to the actual working parameters of the engine, including the main flow channel temperature, main flow channel pressure, flow rate, Mach number, etc., to ensure the flow field environment of the wave-absorbing and fluid-guided stealth coating test piece 21 when it is in working condition.

[0033] In this application, the exhaust section 3 includes an exhaust duct 31 and a cooling section 32. The exhaust duct 31 is connected to the exhaust support plate 24, and the cooling section 32 is located on the rear side of the exhaust duct 31 to cool the gas flowing through the exhaust duct 31.

[0034] In this application, the cooling air system 4 includes a compressed air control system 41 and an electric heater 42. The compressed air control system 41 mainly consists of a flow meter 45, a three-way valve 43, and an exhaust regulating valve 44. The flow meter 45 is installed at the front end of the electric heater 42, and the rear end of the electric heater 42 is connected to the inlet of the three-way valve 43. One outlet of the three-way valve 43 is connected to the inlet 211 of the test piece 21, and the other outlet of the three-way valve 43 is connected to the exhaust regulating valve 44 for exhaust. In some embodiments of this application, the three-way valve 43 is a pneumatic three-way valve, enabling rapid pneumatic response and high-frequency remote control. For example, the pneumatic three-way valve can be a T-type three-way ball valve to achieve cooling air diversion. In some embodiments of this application, the exhaust regulating valve 44 can be an electromagnetic regulating valve. The cooling air system 4 is used to provide cooling air with specific flow rate, temperature, and pressure to the metal side cavity of the wave-absorbing fluid stealth coating according to the actual working state of the wave-absorbing fluid stealth coating, ensuring that the temperature field of the wave-absorbing fluid stealth coating during the test is the same as the actual working state of the engine.

[0035] In this application, the testing and data acquisition system 5 includes a temperature measuring instrument, a pressure scanning valve, and KingSCADA software. The temperature measuring instrument is used to measure the surface wall temperature of the wave-absorbing fluid stealth coating, and the pressure scanning valve is used to measure the internal pressure of the test piece 21. The KingSCADA software connects to the temperature probe, pressure probe, flow meter, temperature measuring instrument, pressure scanning valve, etc., and can monitor and acquire test data such as the flow rate, temperature, and pressure of the main air channel, the surface wall temperature of the wave-absorbing fluid stealth coating, the flow rate, temperature, and pressure of the cooling air flowing inside the metal edge, test time, number of cycles, etc., and control the relevant valves.

[0036] The working process of the cooling air system 4 in this application is as follows: cooling air flows in through flow meter 45 and electric heater 42, and is heated to a specified temperature by electric heater 42. The three-way valve 43 is controlled by KingSCADA software. The heated gas flows through the three-way valve 43 along the first flow path to the inlet 211 of the test piece 21 or along the second flow path through the exhaust regulating valve 44 into the exhaust silencer tower (not shown). The first flow path or the second flow path is switched by the three-way valve 43.

[0037] Based on the above-described thermal fatigue testing system, this application also provides a testing method, comprising the following steps:

[0038] S10, during the high-temperature test debugging phase, the three-way valve 43 is controlled by the KingSCADA software to connect the first flow path. Cooling air enters the test piece 21 through the flow meter 45, electric heater 42, and three-way valve 43. When the wall temperature field requirements of the test piece 21 are met, the parameters such as cooling air flow rate, temperature, and pressure, as well as the flow reading of the flow meter 45, the outlet temperature of the electric heater 42, and the inlet pressure of the cooling air are obtained.

[0039] In step S20, during the low-temperature testing and debugging phase, the three-way valve 43 is controlled by the KingSCADA software to connect the second flow path. Cooling air flows into the exhaust silencer tower through the flow meter 45, electric heater 42, three-way valve 43, and exhaust regulating valve 44. By adjusting the opening of the exhaust regulating valve 44, the cooling air flow rate and the pressure before the valve are kept consistent with those in step S10. At this time, the cooling air flow rate and flow resistance of the first and second flow paths are the same, ensuring that the heating capacity of the electric heater 42 on the cooling air is the same after the flow path is switched by the three-way valve 43. After the flow path is switched, the cooling air state entering the test piece 21 is constant, thereby ensuring the stability of the test state in each cycle. The parameters such as cooling air flow rate, temperature, and pressure, as well as the opening of the exhaust regulating valve 44, are obtained at this time.

[0040] S30. During the formal test, according to the cooling air flow rate, temperature, pressure and the opening size of the exhaust regulating valve 44 determined in steps S10 and S20, and based on the wall temperature field requirements of the test piece 21, the duration of cooling air entering and not entering the test piece 21 is determined, thereby determining the switching time of the three-way valve 43, thus realizing the thermal shock cycle state of the wave-absorbing and fluid-conducting stealth coating, and more accurately assessing the stealth coating's resistance to thermal shock.

[0041] The thermal fatigue test system provided in this application for testing the thermal shock resistance of stealth coatings provides cooling air with periodically changing temperature, realizing flow field simulation of the actual working state of the stealth coating of wave-absorbing fluid, and can more accurately assess the thermal shock resistance of the stealth coating. The test method of this application overcomes the shortcomings of traditional electric heaters that cannot "cut off the gas" and have large thermal inertia, and realizes rapid "low temperature-high temperature" cyclic conversion of cooling air inside the metal edge of wave-absorbing fluid.

[0042] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A thermal fatigue testing system for verifying the thermal shock resistance of stealth coatings, characterized in that, include: The transition section is used to introduce the mainstream gas and measure the state of the mainstream gas. The exhaust section is used to discharge the main flow gas and cool the gas. The test blade includes a test specimen and a container device for enclosing the test specimen. The front end of the container device is connected to the transition section, and the rear end of the container device is connected to the exhaust section. The test specimen is inserted into the container device. A cooling air system includes a compressed air control system and an electric heater. The compressed air control system includes a flow meter, a three-way valve, and an exhaust regulating valve. A flow meter is installed at the front end of the electric heater, and the rear end of the electric heater is connected to the inlet of the three-way valve. One outlet of the three-way valve is connected to the inlet of the test piece, and the other outlet of the three-way valve is connected to the exhaust regulating valve for exhaust. The testing and data acquisition system includes a temperature measuring instrument, a pressure scanning valve, and KingSCADA software. The temperature measuring instrument is used to measure the surface wall temperature of the stealth coating, the pressure scanning valve is used to measure the internal pressure of the test piece, and the KingSCADA software is used to monitor and acquire the flow rate, temperature, and pressure of the main airflow, the surface wall temperature of the stealth coating, the flow rate, temperature, and pressure of the cooling air flowing inside the test piece, the test time, the number of cycles, and to control the three-way valve and the exhaust regulating valve.

2. The thermal fatigue testing system for testing the thermal shock resistance of stealth coatings as described in claim 1, characterized in that, The transition section includes an air inlet channel and a test mounting base. The air inlet channel is set on the test platform through the test mounting base. The front end of the air inlet channel is connected to the main channel and is used to introduce the gas in the main channel into the inlet of the test blade cascade. Temperature probes and pressure probes are installed on the air inlet channel or the test mounting base to detect the state of the gas in the main channel.

3. The thermal fatigue testing system for testing the thermal shock resistance of stealth coatings as described in claim 1, characterized in that, The test blade includes an inlet support plate, an exhaust support plate, a test piece fixing base, a top plate, a side plate, and a mounting plate. The inlet support plate, exhaust support plate, test piece fixing base, top plate, and side plate constitute a container device for accommodating the test piece. The test piece is mounted on the container device via the mounting plate. The test piece fixing base is provided with an air intake channel. Cooling gas entering from the inlet of the test piece flows along the interior of the test piece to the air intake channel and then flows into the main flow channel from the air intake channel.

4. The thermal fatigue testing system for testing the thermal shock resistance of stealth coatings as described in claim 3, characterized in that, The exhaust section includes an exhaust duct and a cooling section. The exhaust duct is connected to the exhaust support plate of the test blade cascade, and the cooling section is located on the rear side of the exhaust duct.

5. The thermal fatigue testing system for testing the thermal shock resistance of stealth coatings as described in claim 1, characterized in that, The three-way valve is a pneumatic three-way valve.

6. The thermal fatigue testing system for testing the thermal shock resistance of stealth coatings as described in claim 1, characterized in that, The exhaust regulating valve is an electromagnetic regulating valve.

7. A test method using the thermal fatigue test system for testing the thermal shock resistance of stealth coatings as described in any one of claims 1 to 6, characterized in that, include: S10, during the high-temperature test debugging phase, the three-way valve is controlled by the KingSCADA software to connect the first flow path to the test piece. Cooling air enters the test piece through the flow meter, electric heater, and three-way valve. When the wall temperature field requirements of the test piece are met, the cooling air flow rate, temperature, pressure parameters, flow meter reading, electric heater outlet temperature, and cooling air inlet pressure data are obtained. S20, during the low-temperature testing and commissioning phase, the three-way valve is controlled by the KingSCADA software to connect the second flow path for discharge. Cooling air flows into the exhaust silencer tower through the flow meter, electric heater, three-way valve, and exhaust regulating valve. By adjusting the opening of the exhaust regulating valve, the cooling air flow rate and the pressure before the valve are kept consistent with those in step S10. The cooling air flow rate, temperature, pressure parameters, and the opening of the exhaust regulating valve are obtained at this time. S30. During the formal test, according to the cooling air flow rate, temperature, pressure and the opening of the exhaust regulating valve determined in steps S10 and S20, the duration of cooling air entering and not entering the test piece is determined based on the wall temperature field requirements of the test piece. This determines the switching time of the three-way valve, thereby realizing the thermal shock cycle state of the stealth coating and more accurately assessing the stealth coating's resistance to thermal shock.

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