Transient Convective Heat Transfer Test Method for Ceramic Matrix Composite Components under High Temperature Oxidation

Abstract

The present invention discloses a transient convective heat transfer test method for ceramic matrix composite components under high-temperature oxidation, belonging to the field of engineering thermophysics. The transient flow heat transfer characteristic test method established by the present invention can carry out experimental research on the transient flow heat transfer characteristics of CMC material components in a characteristic environment of high-temperature oxidation, obtain the thermal response characteristics and variation laws of CMC material components at different oxidation temperatures and times, and provide a principle experimental verification method for the analysis model for the application of CMC material components in high-temperature components of aerospace.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering thermophysics, and particularly relates to a transient convective heat transfer test method for ceramic matrix composite components under high-temperature oxidation. Background Art

[0002] Facing the design requirements of future higher thermal cycle parameters (gas temperature exceeding 2200K), longer component life and reliability (life exceeding 6000 hours), etc. for a new generation of aero-engines, especially the development of high-temperature components represented by turbine blades has brought prominent challenges. The existing design capabilities of turbine blades based on superalloys have tended to reach their limits, and the application of composite materials represented by ceramic matrix composites (CMC) provides the most promising solution.

[0003] The CMC used in the hot-end components of aero-engines, whether it is C / SiC composite or SiC / SiC composite, is usually manufactured by methods such as CVI, PIP, and RMI. During the preparation process, pores will inevitably be generated inside the CMC. In addition, the huge difference in the thermal expansion coefficients between the fibers and the matrix will cause microcracks to form in the matrix. These pores and microcracks provide channels for the oxidation medium to enter the material interior when the CMC hot-end components are in service. As the service time of the CMC hot-end components accumulates, the fibers and interfaces are gradually oxidized, and the thermal physical properties of the composite material change with the increase of service time, which in turn affects the temperature field distribution characteristics of the CMC hot-end components in the engine service environment and the thermal response characteristics of the CMC hot-end components under the engine transient state. Therefore, it is urgent to obtain the transient convective heat transfer characteristics of CMC hot-end components in a high-temperature oxidation environment to provide support for the temperature field characteristic analysis and cooling design of CMC hot-end components in the high-temperature service environment of aero-engines. The present invention establishes a transient convective heat transfer test method for ceramic matrix composite components under high-temperature oxidation for typical flat components of CMC materials, providing a principle verification test method and platform for the thermal analysis and cooling design of hot-end components of CMC materials in advanced aero-engines in China under high-temperature oxidation service environment characteristics. Summary of the Invention

[0004] The present invention provides a transient convective heat transfer test method for ceramic matrix composite components under high-temperature oxidation, which can carry out experimental research on the transient flow heat transfer characteristics of CMC material components in a high-temperature oxidation characteristic environment, and obtain the thermal response characteristics and variation laws of CMC material components at different oxidation temperatures and times.

[0005] An embodiment of the present invention provides a transient convective heat transfer test method for ceramic matrix composite components under high-temperature oxidation, including the following steps:

[0006] Step 1: Measure the mass, equivalent thermal conductivity, and thermal diffusivity of the CMC material flat component according to the representative characteristics of the CMC material flat component.

[0007] Step 2: Install the test CMC material flat component on the transient heat response test section, which has two high-temperature mainstream outlets regulated by a transient heat flux switching plugboard. During the experiment, adjust the cold flow in the transient heat response test section channel to reach the test setting and maintain stability.

[0008] Step 3: Open the second transient heat flux switching plugboard 2 of the transient heat response test section, close the first transient heat flux switching plugboard 1, open the gas supply system so that the high-temperature mainstream flows out from the second heat outlet 2, and wait until the high-temperature mainstream reaches the test demand state and remains stable.

[0009] Step 4: Open the first transient heat flux switching plugboard 1 of the transient heat response test section, close the second transient heat flux switching plugboard 2, make the high-temperature mainstream with stable temperature flow into the test section and flow out from the first heat outlet 1 of the test section, thereby providing a transient convective heat transfer boundary condition for the CMC flat component, and at the same time, use an infrared thermal imager to capture the change law of the hot wall surface temperature of the CMC flat component.

[0010] Step 5: After heating the high-temperature furnace to the preset oxidation temperature, put the test CMC material flat component into the high-temperature furnace and keep it for the preset duration, then take out the test CMC material flat component from the high-temperature furnace. Repeat the above steps multiple times for the test CMC material flat component after high-temperature oxidation to obtain the transient heat response characteristics of CMC components at different oxidation temperatures and different oxidation durations.

[0011] Optionally, in an embodiment of the present invention, sealing strips are used for the first transient heat flux switching plugboard 1 and the second transient heat flux switching plugboard 2 to ensure that the high-temperature mainstream does not leak from the side branch outlet during the test process.

[0012] Optionally, in an embodiment of the present invention, in Step 5, by continuously superimposing the oxidation time for the same test CMC material flat component at the same oxidation temperature, the influence of the oxidation time on the heat response characteristics of the CMC component is obtained.

[0013] By performing high-temperature oxidation at different temperatures for different test CMC material flat components within the same oxidation time, the influence of the oxidation temperature on the heat response characteristics of the CMC component is obtained.

[0014] The transient convective heat transfer test method for ceramic matrix composite components under high-temperature oxidation in the embodiments of the present invention has the following beneficial effects:

[0015] 1) The present invention simulates the high-temperature characteristics of the service environment of an aero-engine through a high-temperature furnace, which is simpler and more efficient compared to directly constructing an ultra-high-temperature mainstream gas environment. At the same time, it can accurately control the oxidation temperature and oxidation time, and thus can conduct a quantitative analysis of the thermal response characteristics of CMC components under high-temperature oxidation.

[0016] 2) By switching the switches of the transient heat flux switching plate 1 and the transient heat flux switching plate 2, the present invention realizes the instantaneous switching of the high-temperature mainstream boundary of the CMC component, can efficiently and accurately control the high-temperature mainstream convective heat transfer boundary of the CMC high-temperature component, and thus provides accurate thermal boundary conditions for the thermal response analysis of the CMC component under high-temperature oxidation.

[0017] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be understood through the practice of the present invention. Brief Description of the Drawings

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and easy to understand from the following description of the embodiments in conjunction with the drawings, where:

[0019] Figure 1 is a flowchart of a transient convective heat transfer test method for a ceramic matrix composite component under high-temperature oxidation according to an embodiment of the present invention;

[0020] Figure 2 is a schematic diagram of the test device system according to an embodiment of the present invention;

[0021] Figure 3 is a high-temperature furnace for simulating the oxidation environment according to an embodiment of the present invention;

[0022] Figure 4 is a schematic diagram of the test section according to an embodiment of the present invention;

[0023] Figure 5 is a test photo of the test section and the surface temperature of the CMC component according to an embodiment of the present invention;

[0024] Figure 6 is a photo of the CMC component and a schematic diagram of its dimensions used in the test according to an embodiment of the present invention;

[0025] Figure 7 is the average temperature curve of the hot wall surface at different oxidation times according to an embodiment of the present invention;

[0026] Figure 8 is the average temperature curve of the hot wall surface at different oxidation temperatures according to an embodiment of the present invention. Detailed Embodiments

[0027] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention.

[0028] Figure 1 It is a flowchart of a transient convective heat transfer test method for a ceramic matrix composite component under high-temperature oxidation according to an embodiment of the present invention.

[0029] As Figure 1 shown, the transient convective heat transfer test method for the ceramic matrix composite component under high-temperature oxidation includes the following steps:

[0030] Step 1: Measure the mass, equivalent thermal conductivity, and thermal diffusivity of the CMC material flat component according to the representative characteristics of the CMC material flat component.

[0031] Step 2: Install the test CMC material flat component on the transient thermal response test section, and the transient thermal response test section has two high-temperature mainstream outlets regulated by a transient heat flux switching plugboard. During the experiment, adjust the cold flow in the transient thermal response test section channel to reach the test setting and remain stable.

[0032] Step 3: Open the second transient heat flux switching plugboard 2 of the transient thermal response test section, close the first transient heat flux switching plugboard 1, open the gas supply system so that the high-temperature mainstream flows out from the second heat outlet 2, and wait until the high-temperature mainstream reaches the test demand state and remains stable.

[0033] Step 4: Open the first transient heat flux switching plugboard 1 of the transient thermal response test section, close the second transient heat flux switching plugboard 2, make the high-temperature mainstream with stable temperature flow into the test section and flow out from the first heat outlet 1 of the test section, thereby providing a transient convective heat transfer boundary condition for the CMC flat component, and simultaneously photograph the temperature change law of the hot wall surface of the CMC flat component through an infrared thermal imager.

[0034] Step 5: After heating the high-temperature furnace to the preset oxidation temperature, put the test CMC material flat component into the high-temperature furnace and keep it for the preset duration, take out the test CMC material flat component from the high-temperature furnace, and repeat the above steps multiple times for the test CMC material flat component after high-temperature oxidation to obtain the transient thermal response characteristics of the CMC component at different oxidation temperatures and different oxidation durations.

[0035] Optionally, in an embodiment of the present invention, a sealing strip is used for the first transient heat flux switching plugboard 1 and the second transient heat flux switching plugboard 2 to ensure that the high-temperature mainstream does not leak from the side branch outlet during the test process.

[0036] Optionally, in an embodiment of the present invention, in step 5, by continuously superimposing the oxidation time for the same test CMC material flat component at the same oxidation temperature, the influence of the oxidation time on the thermal response characteristics of the CMC component is obtained;

[0037] By performing high-temperature oxidation at different temperatures for different test CMC material flat components within the same oxidation time, the influence of the oxidation temperature on the thermal response characteristics of the CMC component is obtained.

[0038] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0039] Embodiment: Experiment on the transient flow heat transfer characteristics of ceramic matrix composite components under high-temperature oxidation.

[0040] The test system consists of two parts. The first part mainly consists of a high-temperature oxidation device and a thermal property testing device, which is used to provide a high-temperature oxidation simulation environment and test thermal property parameters for the CMC material. The second part consists of a gas supply system, a signal measurement and acquisition system, and a test section, which are used to test the transient thermal response characteristics of the CMC component under the condition of convective heat transfer of high-temperature gas flow. The high-temperature oxidation device mainly includes a high-temperature furnace, the thermal property testing device includes a laser thermal conductivity tester, the gas supply system includes an air compressor, a flowmeter, a heater, etc., the signal measurement and acquisition system includes temperature and pressure sensors and a signal acquisition instrument, the test section includes a high-temperature main flow, a low-temperature secondary flow channel, and a CMC material test piece. In the test section, the transient convective heat transfer boundary condition on the surface of the CMC material test piece is realized through a transient heat flux switching plugboard, and an infrared thermal imager is used to obtain the thermal response law of the CMC component surface. The entire test system is as Figure 2 shown.

[0041] The high-temperature oxidation system mainly consists of a Kain KNPL-W1000 type high-temperature furnace ( Figure 3 as shown in), its maximum working temperature is 1650 °C, the heating rate is 10 °C / min, and the constant temperature accuracy is 1 ± °C. The thermal physical property testing system includes a laser thermal conductivity tester, and the testing range is 0.1 W / (m·K) to 2000 W / (m·K), which is used to test the thermal diffusivity and specific heat capacity of the sample.

[0042] In the heat flux supply system of this experiment, after the air flow is generated by the air compressor, it first flows into the pressure stabilizing air storage tank to ensure the stability of the subsequent air flow rate. Then the air flow passes through the throttle valve to control it to the required flow rate, and then through the vortex flowmeter, and enters the electric heater with a rated power of 200 kW. Through temperature feedback control, the mainstream air flow reaches the temperature required for the experiment. The heated high-temperature gas then enters the test section after passing through the rectifying section. After the cold air flow is generated by the air compressor, it first flows into the pressure stabilizing air storage tank to ensure the stability of the subsequent cold air flow rate. Then the air flow passes through the throttle valve to control it to the required flow rate, and then through the vortex flowmeter, and finally enters the test section after passing through the rectifying section

[0043] In the test section, the cross-sectional size of the heat flux channel is 140 mm × 100 mm, the cross-sectional size of the cold air flow channel is 60 mm × 60 mm, the size of the test plate is 60 mm × 36 mm. The back of the test plate is flush with the wall surface of the cold air flow channel, and the front of the test plate is flush with the wall surface of the heat flux channel. Finally, the three form an integral whole. There are transient heat flux switching plates and heat flux standby outlets (heat flux outlet 2) upstream of the heat flux experimental section. During the experiment, first open the transient heat flux switching plate 2 and close the transient heat flux switching plate 1, so that the heat flux flows out from the heat flux outlet 2. After the heat flux reaches the test required state and remains stable, open the transient heat flux switching plate 1 and close the transient heat flux switching plate 2, so that the heat flux flows into the test section and flows out from the heat flux outlet 1, so as to provide transient heat flux; The schematic diagram of the test section is as Figure 4 shown in

[0044] The temperature of the CMC plate in contact with the heat flux wall surface is measured by a FLIR A655 type infrared thermal imager, as Figure 5 shown in. The resolution of the temperature field photographed by this thermal imager is 640 × 480, the maximum frame rate (full window) during dynamic shooting is 200 Hz, and the spatial resolution is 1.36 mrad. When using the infrared thermal imager to measure temperature, the temperature measured by the infrared thermal imager is affected by comprehensive factors such as the radiation characteristics (surface topography, emissivity) of the test object itself, the shooting environment, and the transmittance of the shooting window. The characteristic temperature on the hot wall surface is measured by a high-precision K-type thermocouple. By linearly fitting the measured values of the two at different temperatures, the fitting relationship between the two is obtained to calibrate the temperature measured by the infrared thermal imager, as Figure 6 shown in

[0045] Figure 7The average temperature curve of the hot wall is given after the CMC flat plate is oxidized at 1373K for different times. After reaching the steady state, compared with the situation before oxidation, the average temperature on the hot wall increases by 0.48% and 1.04% respectively after 2h and 6h of oxidation. During the transient heat response process, after 2h and 6h of oxidation, the average temperatures on the hot wall are 338.21K and 342.46K respectively (the heat response time is 60s), increasing by 1.33% and 2.60% respectively compared with that before oxidation. Thus, it can be seen that the influence of high-temperature oxidation on the transient temperature of the CMC flat plate is higher than that on the steady-state temperature.

[0046] Figure 8 The change curves of the average temperature of the hot wall are given at different oxidation temperatures. As can be seen from the figure, when the oxidation temperatures are 873K, 1073K, and 1373K respectively, the average temperatures of the hot wall after reaching the steady state after 6h of oxidation are 346.42K, 3483.83K, and 351.16K respectively; the change in the transient heat response characteristics of the flat plate caused by the change in oxidation temperature is similar to the influence of oxidation time on the heat response characteristics of the flat plate, because higher oxidation temperature and longer oxidation time will both reduce the heat conduction ability of the yarn, thereby bringing about changes in the transient heat response characteristics.

[0047] Based on the transient flow and heat transfer characteristics test method established by the present invention, the transient flow and heat transfer characteristics test research can be carried out for CMC material components in a high-temperature oxidation characteristic environment, and the heat response characteristics and change laws of CMC material components at different oxidation temperatures and times can be obtained, providing a principle test verification method for the analysis model for the application of CMC material components in aerospace high-temperature components.

[0048] According to the transient convective heat transfer test method for ceramic matrix composite components under high-temperature oxidation proposed in the embodiment of the present invention, the established transient flow and heat transfer characteristics test method can carry out the transient flow and heat transfer characteristics test research for CMC material components in a high-temperature oxidation characteristic environment, obtain the heat response characteristics and change laws of CMC material components at different oxidation temperatures and times, and provide a principle test verification method for the analysis model for the application of CMC material components in aerospace high-temperature components.

[0049] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0050] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, the meaning of "N" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0051] Any process or method description shown in the flowchart or described in other ways herein can be understood to represent a module, segment, or portion of code including one or N executable instructions for implementing a customized logic function or process, and the scope of the preferred embodiments of the present invention includes additional implementations, where the functions can be executed in a substantially simultaneous manner or in a reverse order according to the functions involved, rather than in the order shown or discussed, which should be understood by those skilled in the art to which the embodiments of the present invention pertain.

Claims

1. A transient convective heat transfer test method for ceramic matrix composite components under high-temperature oxidation, characterized in that It includes the following steps: Step 1: Measure the mass, equivalent thermal conductivity, and thermal diffusivity of the CMC material flat component for the representative characteristics of the CMC material flat component. Step 2: Install the test CMC material flat component on the transient thermal response test section. The transient thermal response test section has two high-temperature mainstream outlets regulated by a transient heat flux switching plugboard. During the experiment, adjust the cold flow in the transient thermal response test section channel to reach the test setting and remain stable. Step 3: Open the second transient heat flux switching plugboard of the transient thermal response test section, close the first transient heat flux switching plugboard, open the gas supply system to make the high-temperature mainstream flow out from the second heat outlet, and wait until the high-temperature mainstream reaches the test demand state and remains stable. Step 4: Open the first transient heat flux switching plugboard of the transient thermal response test section, close the second transient heat flux switching plugboard, make the high-temperature mainstream with stable temperature flow into the test section and flow out from the first heat outlet of the test section, thereby providing a transient convective heat transfer boundary condition for the CMC material flat component. At the same time, use an infrared thermal imager to capture the change law of the hot wall surface temperature of the CMC material flat component. Step 5: After heating the high-temperature furnace to the preset oxidation temperature, put the test CMC material flat component into the high-temperature furnace and keep it for the preset duration. Take out the test CMC material flat component from the high-temperature furnace. Repeat the above steps multiple times for the test CMC material flat component after high-temperature oxidation to obtain the transient thermal response characteristics of the CMC material flat component at different oxidation temperatures and different oxidation durations.

2. The method according to claim 1, wherein In Step 3 and Step 4, use a sealing strip for the first transient heat flux switching plugboard and the second transient heat flux switching plugboard to ensure that the high-temperature mainstream will not leak from the side branch outlet during the test process.

3. The method according to claim 1, characterized in that In Step 5, obtain the influence of the oxidation time on the thermal response characteristics of the CMC material flat component by continuously superimposing the oxidation time for the same test CMC material flat component at the same oxidation temperature. Obtain the influence of the oxidation temperature on the thermal response characteristics of the CMC material flat component by conducting high-temperature oxidation at different temperatures for different test CMC material flat components within the same oxidation time.

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