A method and system for determining heat transfer coefficient of thermal barrier coating

Abstract

The present invention relates to the field of nondestructive testing, and in particular to a method and system for determining the heat transfer coefficient of a thermal barrier coating, the method comprising obtaining temperature information and thermal conductivity of the thermal barrier coating; the temperature information comprises gas temperature, ceramic layer top temperature, ceramic layer bottom temperature, substrate temperature and cooling gas temperature; the ceramic layer top temperature is the temperature of the ceramic layer side close to the gas; the ceramic layer bottom temperature is the temperature of the ceramic layer side close to the bonding layer; the thermal conductivity comprises the thermal conductivity of the ceramic and the thermal conductivity of the substrate; the heat transfer coefficient of the thermal barrier coating is determined according to the temperature information of the thermal barrier coating and the thermal conductivity; the heat transfer coefficient of the thermal barrier coating is used to determine the thermal insulation performance of the thermal barrier coating. The present invention can improve the determination accuracy of the heat transfer coefficient of the thermal barrier coating.

Description

Technical Field

[0001] The present invention relates to the field of nondestructive testing, and in particular to a method and system for determining a heat transfer coefficient of a thermal barrier coating. Background Art

[0002] With the increase of inlet combustion temperature, thrust-to-weight ratio and thermal efficiency of gas turbine engines, the hot end components of the engine, especially the gas temperature and gas pressure in the combustion chamber, continue to increase, and the requirements for high-temperature alloys are becoming more stringent. In pursuit of higher cycle efficiency and economy, how to use reasonable cooling methods to reduce the surface temperature of the alloy to a reasonable range has become an issue that gas turbine blade designers must consider. As an indispensable technology for future engines, the accurate evaluation and prediction of thermal insulation performance of thermal barrier coating technology is a key issue for optimizing turbine blade design and improving engine performance. Theoretically evaluating the thermal insulation effect of thermal barrier coatings plays an important role in the feasibility design of turbine blades. In order to accurately calculate the thermal insulation temperature difference of thermal barrier coatings, accurately measuring the convective heat transfer coefficient of the thermal barrier coating surface becomes a crucial link.

[0003] The convective heat transfer coefficient is related to many factors such as the physical properties and state of the fluid and the heat transfer surface. There is still no clear formula to reflect how these factors affect the convective heat transfer coefficient. How to obtain an accurate convective heat transfer coefficient is a difficulty in engineering. Summary of the invention

[0004] The object of the present invention is to provide a method and system for determining the heat transfer coefficient of a thermal barrier coating, so as to improve the determination accuracy of the heat transfer coefficient of the thermal barrier coating.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A method for determining a heat transfer coefficient of a thermal barrier coating, comprising:

[0007] Obtaining temperature information and thermal conductivity of the thermal barrier coating; the temperature information includes gas temperature, ceramic layer top temperature, ceramic layer bottom temperature, substrate temperature and cooling gas temperature; the ceramic layer top temperature is the temperature of the ceramic layer side close to the gas; the ceramic layer bottom temperature is the temperature of the ceramic layer side close to the bonding layer; the thermal conductivity includes the thermal conductivity of the ceramic and the thermal conductivity of the substrate;

[0008] The heat transfer coefficient of the thermal barrier coating is determined according to the temperature information of the thermal barrier coating and the thermal conductivity; the heat transfer coefficient of the thermal barrier coating is used to determine the thermal insulation performance of the thermal barrier coating.

[0009] Optionally, obtaining the temperature information and thermal conductivity of the thermal barrier coating specifically includes:

[0010] obtaining the gas temperature;

[0011] Obtaining the top temperature of the ceramic layer using a colorimetric thermometer;

[0012] Using a thin film thermocouple to obtain the bottom temperature of the ceramic layer;

[0013] Obtaining the substrate temperature using a K-type thermocouple;

[0014] The cooling gas temperature is obtained by using a three-point temperature measurement method;

[0015] The thermal conductivity is measured using a laser flash method.

[0016] Optionally, determining the heat transfer coefficient of the thermal barrier coating according to the temperature information of the thermal barrier coating and the thermal conductivity coefficient specifically includes:

[0017] Determine the heat flux density equation of convective heat transfer between the fuel gas and the ceramic layer during the heat absorption process according to the fuel gas temperature and the top temperature of the ceramic layer using the convection heat transfer principle;

[0018] Determine the heat flux density equation of the radiation heat exchange between the gas and the substrate during the heat absorption process according to the gas temperature and the top temperature of the ceramic layer using the radiation heat exchange principle;

[0019] Determine the heat flux density equation of heat conduction of the ceramic layer during heat dissipation according to the top temperature of the ceramic layer, the bottom temperature of the ceramic layer and the thermal conductivity of the ceramic by using the heat conduction principle;

[0020] Determine the heat flux density equation of the heat conduction of the substrate during the heat dissipation process according to the bottom temperature of the ceramic layer, the substrate temperature and the thermal conductivity of the substrate using the heat conduction principle;

[0021] Determine the heat flux density equation of convection heat transfer during cooling in the heat dissipation process according to the substrate temperature and the cooling gas temperature based on the convection heat transfer principle;

[0022] The heat transfer coefficient of the thermal barrier coating is determined according to the heat flux density equation for convective heat transfer between the fuel gas and the ceramic layer during the heat absorption process, the heat flux density equation for radiation heat transfer between the fuel gas and the substrate during the heat absorption process, the heat flux density equation for heat conduction of the ceramic layer during the heat dissipation process, the heat flux density equation for heat conduction of the substrate during the heat dissipation process, and the heat flux density equation for convective heat transfer during cooling during the heat dissipation process.

[0023] Optionally, the heat flux density equation for convective heat transfer between the fuel gas and the ceramic layer during the heat absorption process is specifically:

[0024] q 1 =h 1 (T g1 -T 1 )

[0025] Among them, q 1 is the heat flux density of convective heat transfer between the gas and the ceramic layer during the heat absorption process, h 1 is the convection heat transfer coefficient between the gas and the ceramic layer, T g1 is the gas temperature, T 1 is the top temperature of the ceramic layer.

[0026] Optionally, the heat flux density equation for the radiation heat exchange between the fuel gas and the substrate during the heat absorption process is specifically:

[0027]

[0028] Among them, q 2 The heat flux density of the radiation heat exchange between the gas and the substrate during the endothermic process, ε 1 is the matrix blackness, T g1 is the gas temperature, T 1 is the top temperature of the ceramic layer.

[0029] Optionally, the heat flux density equation of heat conduction of the ceramic layer during the heat dissipation process is specifically:

[0030]

[0031] Among them, q 3 is the heat flux density of the ceramic layer during heat dissipation, λ c is the thermal conductivity of ceramics, T 1 is the top temperature of the ceramic layer, T 2 is the bottom temperature of the ceramic layer, δ c is the thickness of the ceramic layer.

[0032] Optionally, the heat flux density equation of the substrate heat conduction during the heat dissipation process is specifically:

[0033]

[0034] Among them, q 4 is the heat flux density of the substrate heat conduction during the heat dissipation process, λ s is the thermal conductivity of the matrix, δ s is the substrate thickness, T 2 is the bottom temperature of the ceramic layer, T 3 is the substrate temperature.

[0035] Optionally, the heat flux density equation of convection heat transfer during cooling in the heat dissipation process is specifically:

[0036] q 5 =h 2 (T 3 -T a2 )

[0037] Among them, q 5 is the heat flux density of convection heat transfer during cooling in the heat dissipation process, h 2 is the convective heat transfer coefficient between the substrate and the cooling gas, T 3 is the substrate temperature, T a2 is the cooling gas temperature.

[0038] Optionally, the expression of the heat transfer coefficient of the thermal barrier coating is specifically:

[0039]

[0040] Among them, h 1 is the convection heat transfer coefficient between the gas and the ceramic layer, T g1 is the gas temperature, T 1 is the top temperature of the ceramic layer, ε 1 is the blackness of the blade, λ c is the thermal conductivity of ceramics, T 2 is the bottom temperature of the ceramic layer, δ c is the thickness of the ceramic layer, T 3 is the substrate temperature, h 2 is the convective heat transfer coefficient between the substrate and the cooling gas, T a2 is the cooling gas temperature.

[0041] A system for determining heat transfer coefficient of a thermal barrier coating, comprising:

[0042] An acquisition module is used to acquire temperature information and thermal conductivity of the thermal barrier coating; the temperature information includes the gas temperature, the top temperature of the ceramic layer, the bottom temperature of the ceramic layer, the substrate temperature and the cooling gas temperature; the top temperature of the ceramic layer is the temperature of the side of the ceramic layer close to the gas; the bottom temperature of the ceramic layer is the temperature of the side of the ceramic layer close to the bonding layer; the thermal conductivity includes the thermal conductivity of the ceramic and the thermal conductivity of the substrate;

[0043] The thermal barrier coating heat transfer coefficient determination module is used to determine the thermal barrier coating heat transfer coefficient according to the temperature information of the thermal barrier coating and the thermal conductivity; the thermal barrier coating heat transfer coefficient is used to determine the thermal insulation performance of the thermal barrier coating.

[0044] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0045] The present invention obtains temperature information and thermal conductivity of a thermal barrier coating; the temperature information includes gas temperature, ceramic layer top temperature, ceramic layer bottom temperature, substrate temperature and cooling gas temperature; the ceramic layer top temperature is the temperature of the ceramic layer side close to the gas; the ceramic layer bottom temperature is the temperature of the ceramic layer side close to the bonding layer; the thermal conductivity includes the thermal conductivity of the ceramic and the thermal conductivity of the substrate; the thermal barrier coating heat transfer coefficient is determined according to the temperature information of the thermal barrier coating and the thermal conductivity; the thermal barrier coating heat transfer coefficient is used to determine the thermal insulation performance of the thermal barrier coating. The heat transfer conditions of each part of the thermal barrier coating are determined by obtaining the gas temperature, the ceramic layer top temperature, the ceramic layer bottom temperature, the substrate temperature and the cooling gas temperature, thereby improving the accuracy of determining the thermal barrier coating heat transfer coefficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0047] Figure 1 A flow chart of a method for determining a heat transfer coefficient of a thermal barrier coating provided by the present invention;

[0048] Figure 2 A temperature distribution diagram of the thermal barrier coating system provided by the present invention;

[0049] Figure 3 Schematic diagram of the thermal barrier coating thermal insulation testing device provided by the present invention. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] The object of the present invention is to provide a method and system for determining the heat transfer coefficient of a thermal barrier coating, so as to improve the determination accuracy of the heat transfer coefficient of the thermal barrier coating.

[0052] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0053] The present invention utilizes a long-wave infrared dual colorimetric thermometer, a thin film thermocouple and a standard thermocouple to respectively measure the temperatures of the coating surface, the interface between the coating and the alloy, the bottom of the alloy, the impact flame and the cooling airflow, and finally substitutes them into a formula for solving the problem to obtain the surface convective heat transfer coefficient of the thermal barrier coating.

[0054] Taking a gas turbine engine as an example, from the perspective of heat transfer, the thermal barrier coating first absorbs energy from the high-temperature combustion gas, mainly in the form of radiation heat exchange and forced convection; then part of the energy is transferred to the cylinder in the form of radiation, part of it is transferred to the blade substrate material by conduction, and then carried away by the cooling air inside the substrate material in the form of forced convection, and finally a small amount is transferred to the shaft and cylinder by conduction and to the combustion gas by radiation.

[0055] From the above analysis, it can be seen that thermal barrier coating components absorb and dissipate heat in the service environment. The process of absorbing heat and heating up mainly occurs through two heat transfer methods: convection heat transfer and radiation heat transfer. Since the thermal barrier coating system always maintains a dynamic balance during the heat transfer process, after the top of the thermal barrier coating absorbs heat, it will dissipate it in different forms such as conduction, radiation, and convection.

[0056] like Figure 1 As shown, the present invention provides a method for determining the heat transfer coefficient of a thermal barrier coating, comprising:

[0057] Step 101: Obtain the temperature information and thermal conductivity of the thermal barrier coating; the temperature information includes the gas temperature, the top temperature of the ceramic layer, the bottom temperature of the ceramic layer, the substrate temperature and the cooling gas temperature; the top temperature of the ceramic layer is the temperature of the ceramic layer side close to the gas; the bottom temperature of the ceramic layer is the temperature of the ceramic layer side close to the bonding layer; the thermal conductivity includes the thermal conductivity of the ceramic and the thermal conductivity of the substrate. In practical applications, when the expression of the heat transfer coefficient of the thermal barrier coating is constructed, the heat transfer coefficient of the thermal barrier coating can be determined by obtaining the thermal conductivity as one of the thermal conductivity of the ceramic or the thermal conductivity of the substrate.

[0058] Step 101 specifically includes: obtaining the gas temperature; obtaining the top temperature of the ceramic layer using a colorimetric thermometer; obtaining the bottom temperature of the ceramic layer using a thin film thermocouple; obtaining the substrate temperature using a K-type thermocouple; obtaining the cooling gas temperature using a three-point temperature measurement method; and measuring the thermal conductivity using a laser flash method.

[0059] Step 102: determining a heat transfer coefficient of the thermal barrier coating according to the temperature information of the thermal barrier coating and the thermal conductivity; the heat transfer coefficient of the thermal barrier coating is used to determine the thermal insulation performance of the thermal barrier coating.

[0060] Step 102, determining the heat transfer coefficient of the thermal barrier coating according to the temperature information of the thermal barrier coating and the thermal conductivity, specifically includes:

[0061] The heat flux density equation of the convective heat transfer between the fuel gas and the ceramic layer during the heat absorption process is determined according to the fuel gas temperature and the top temperature of the ceramic layer using the convective heat transfer principle.

[0062] The heat absorption process includes convection heat transfer and radiation heat transfer.

[0063] like Figure 2 As shown, in convective heat transfer, the temperature of the high-temperature gas is T g1 , the top temperature of the ceramic layer is T 1 The temperature at the bottom of the ceramic layer, i.e. the top of the bonding layer, is T 2 The inner wall temperature of the blade, i.e. the base temperature, is T 3 , where the cooling air flow temperature is the average temperature of the cooling air flow T a2 According to the theoretical calculation formula, the heat flux density equation for convective heat transfer between the fuel gas and the ceramic layer during the heat absorption process is specifically:

[0064] q 1 =h 1 (T g1 -T 1 ) (1)

[0065] Among them, q 1 is the heat flux density of convective heat transfer between the gas and the ceramic layer during the heat absorption process, h 1 is the convection heat transfer coefficient between the gas and the ceramic layer, T g1 is the gas temperature, T 1 is the top temperature of the ceramic layer.

[0066] The heat flux density equation of the radiation heat exchange between the fuel gas and the substrate during the heat absorption process is determined according to the fuel gas temperature and the top temperature of the ceramic layer using the radiation heat exchange principle.

[0067] In radiation heat transfer, there is a strong radiation heat transfer between the high-temperature gas and the thermal barrier coating system. When calculating the radiation heat transfer between any surface and the outside world, the radiation energy emitted from the surface in all directions of space must be taken into account, and the radiation energy invested in the surface from all directions of space must also be included. Therefore, the thermal barrier coating in the combustion chamber is treated as a "closed cavity" model. Therefore, the radiation heat transfer between the high-temperature gas and the blade is:

[0068] Φ 1,2 =A 1 J 1 X 1 -A 2 J 2 X 2 (2)

[0069] Among them, A 1 is the surface area, J1 is the effective radiation of surface 1, X 1 is the surface 1 angle factor, A 2 is the surface area, J 2 is the effective radiation of surface 2, X 2 is the angular coefficient of surface 2.

[0070] The relationship between effective radiation J and surface net heat transfer q is:

[0071]

[0072] Among them, E is the actual radiation force, a is the absorption rate, and E b is the blackbody radiation power, and ε is the blackness.

[0073] According to the law of conservation of energy: Φ 1,2 =Φ 2,1 We can get:

[0074]

[0075] Φ 2,1 is the radiation heat transfer from surface 2 to surface 1, E b1 is the blackbody radiation force on surface 1, E b2 is the blackbody radiation force on surface 2, X 1,2 is the angle coefficient of surface 1 to surface 2, ε 2 The surface is 2 degrees black.

[0076] Considering that the blade surface area is much smaller than the cylinder area, that is, X 1,2 =1. At this time, formula (4) can be simplified to:

[0077]

[0078] Since the blade is a thin-walled part with a very small ratio of thickness to length, it can be approximately regarded as a flat plate heat transfer. The blade is the matrix, so the heat flux density equation for the radiation heat exchange between the gas and the matrix during the heat absorption process is specifically:

[0079]

[0080] Among them, q 2 The heat flux density of the radiation heat exchange between the gas and the substrate during the endothermic process, ε 1 is the matrix blackness, T g1 is the gas temperature, T 1 is the top temperature of the ceramic layer.

[0081] The heat flux density equation of heat conduction of the ceramic layer during the heat dissipation process is determined by utilizing the heat conduction principle according to the top temperature of the ceramic layer, the bottom temperature of the ceramic layer and the thermal conductivity of the ceramic.

[0082] Heat conduction during heat dissipation:

[0083] The top of the ceramic layer is heated to T 1 Later, with the ceramic layer bottom T 2 The temperature difference will cause heat conduction, wherein the heat flux density equation of the heat conduction of the ceramic layer during the heat dissipation process is specifically:

[0084]

[0085] Among them, q 3 is the heat flux density of the ceramic layer during heat dissipation, λ c is the thermal conductivity of ceramics, T 1 is the top temperature of the ceramic layer, T 2 is the bottom temperature of the ceramic layer, δ c is the thickness of the ceramic layer.

[0086] The heat flux density equation of the heat conduction of the substrate during the heat dissipation process is determined by using the heat conduction principle according to the bottom temperature of the ceramic layer, the substrate temperature and the thermal conductivity of the substrate. The heat flow passes through the ceramic layer to the interface between the ceramic layer and the bonding layer, that is, the outer wall of the metal substrate. Since there is still a temperature difference between the inner and outer walls of the metal substrate, heat conduction will inevitably occur. At this time, the heat flux density equation of the heat conduction of the substrate during the heat dissipation process is specifically:

[0087]

[0088] Among them, q 4 is the heat flux density of the substrate heat conduction during the heat dissipation process, λ s is the thermal conductivity of the matrix, δ s is the substrate thickness, T 2 is the bottom temperature of the ceramic layer, T 3 is the substrate temperature.

[0089] According to the convection heat transfer principle, the convection heat flux density equation during cooling in the heat dissipation process is determined according to the substrate temperature and the cooling gas temperature.

[0090] Convective heat transfer during heat dissipation:

[0091] After the heat flux passes through the metal matrix, it will undergo convective heat exchange with the cooling gas, and the cooling gas will take away the heat. The heat flux density equation for convective heat transfer during cooling in the heat dissipation process is specifically:

[0092] q 5 =h 2 (T 3 -T a2 ) (9)

[0093] Among them, q5 is the heat flux density of convection heat transfer during cooling in the heat dissipation process, h 2 is the convective heat transfer coefficient between the substrate and the cooling gas, T 3 is the substrate temperature, T a2 is the cooling gas temperature.

[0094] The heat transfer coefficient of the thermal barrier coating is determined according to the heat flux density equation for convective heat transfer between the fuel gas and the ceramic layer during the heat absorption process, the heat flux density equation for radiation heat transfer between the fuel gas and the substrate during the heat absorption process, the heat flux density equation for heat conduction of the ceramic layer during the heat dissipation process, the heat flux density equation for heat conduction of the substrate during the heat dissipation process, and the heat flux density equation for convective heat transfer during cooling during the heat dissipation process.

[0095] The heat transfer process of thermal barrier coatings during service is very complicated. For example, it also includes contact conduction between the ceramic layer and high-temperature combustion gas, contact conduction between the metal and the cold end of the substrate and cooling air, and radiation heat exchange at the cold end of the metal substrate. However, compared with the above main heat transfer mechanisms, the heat transfer in these forms is very small and can be ignored in the calculation.

[0096] From the above analysis, we can know that:

[0097] q 1 +q 2 =q 3 =q 4 =q 5 (10)

[0098] Combining equations (1)-(10) we can obtain:

[0099]

[0100] Solved: The expression of the heat transfer coefficient of the thermal barrier coating is specifically:

[0101]

[0102] Among them, h 1 is the convection heat transfer coefficient between the gas and the ceramic layer, T g1 is the gas temperature, T 1 is the top temperature of the ceramic layer, ε 1 is the matrix blackness, λ c is the thermal conductivity of ceramics, T 2 is the bottom temperature of the ceramic layer, δ c is the thickness of the ceramic layer, T 3 is the substrate temperature, h 2 is the convective heat transfer coefficient between the substrate and the cooling gas, T a2 is the cooling gas temperature.

[0103] Formula (12) is a theoretical calculation formula. It can be seen from the formula that the temperature point T is required to solve the surface heat transfer coefficient of the thermal barrier coating. g1 、T 1 、T 2 、T 3 、T a2 These values ​​can be directly read from the experimental equipment, and the thermal conductivity λ c , s It is possible to measure using the laser flash method.

[0104] The present invention also provides a system for determining a heat transfer coefficient of a thermal barrier coating corresponding to a method for determining a heat transfer coefficient of a thermal barrier coating, comprising:

[0105] An acquisition module is used to obtain temperature information and thermal conductivity of the thermal barrier coating; the temperature information includes the gas temperature, the top temperature of the ceramic layer, the bottom temperature of the ceramic layer, the substrate temperature and the cooling gas temperature; the top temperature of the ceramic layer is the temperature of the side of the ceramic layer close to the gas; the bottom temperature of the ceramic layer is the temperature of the side of the ceramic layer close to the bonding layer; the thermal conductivity includes the thermal conductivity of the ceramic and the thermal conductivity of the substrate.

[0106] The thermal barrier coating heat transfer coefficient determination module is used to determine the thermal barrier coating heat transfer coefficient according to the temperature information of the thermal barrier coating and the thermal conductivity; the thermal barrier coating heat transfer coefficient is used to determine the thermal insulation performance of the thermal barrier coating.

[0107] like Figure 3 As shown, the present invention also provides a working process of a method for determining a heat transfer coefficient of a thermal barrier coating in a specific application.

[0108] In the first step, the entire device is carried out in a closed chamber to avoid heat exchange and transfer with the outside world.

[0109] In the second step, the thermal barrier coating sample is fixed to the instrument with a clamp to avoid swinging.

[0110] For example, atmospheric plasma spraying technology is used to prepare bonding layers and ceramic layers on IC21 high-temperature alloy, with thicknesses of 50 μm and 150 μm respectively. The prepared thermal barrier coating specimens are fixed on the test device using appropriate fixtures.

[0111] The third step is to debug each temperature measuring equipment, use a long-wave infrared dual-colorimetric thermometer to measure the surface temperature of the thermal barrier coating, use a thin-film thermocouple to measure the interface temperature between the substrate and the coating, use a K-type thermocouple to measure the bottom temperature of the alloy substrate, and use the three-point temperature measurement method to measure the cooling air flow temperature.

[0112] The fourth step is to open the impact flame and introduce cooling airflow to control the temperature and flow rate of the flame and cooling airflow.

[0113] For example, debug each temperature measuring instrument to ensure normal operation, turn on the impact flame, control the flame temperature to 1500℃, the flow rate to 200m / s, introduce cooling gas, control the temperature to 700℃, and the flow rate to 100m / s.

[0114] Step 5: When the whole device is in a steady state, read the temperature values ​​on each temperature measuring instrument and correspond to T g1 , T 1 , T 2 , T 3 , T a2 .

[0115] Step 6: Substitute each temperature value into equation (12) to obtain the convective heat transfer coefficient h 1 、h 2 .

[0116] The method for determining the heat transfer coefficient of a thermal barrier coating provided by the present invention belongs to the field of non-destructive testing and is used to evaluate and test the thermal insulation performance of thermal barrier coatings for turbine blades of aircraft engines. The present invention solves the problem that it is difficult to measure the heat transfer coefficient of the surface of a thermal barrier coating in a service state. It can be seen from the relevant theories of heat transfer that there are many factors that affect the convective heat transfer coefficient (such as the physical properties of the fluid, the shape, size and position of the heat transfer surface, etc.). If these factors are fully considered, the calculation process is too complicated and difficult to carry out. Starting from the theoretical formula, the present invention builds a corresponding experimental platform and combines a variety of temperature measurement methods to determine the heat transfer coefficient of the surface of the thermal barrier coating. First, the real service environment of the turbine blade is simulated, the surface of the thermal barrier coating is subjected to flame impact by a spray gun, and the high-temperature alloy substrate is cooled by air flow. The temperature of the coating surface, the interface between the coating and the alloy, the bottom of the alloy, the impact flame and the cooling air flow are measured respectively by using a long-wave infrared dual colorimetric thermometer, a thin film thermocouple and a standard thermocouple, and finally it is brought into formula (12) for solution. This method can effectively determine the heat transfer coefficient of the thermal barrier coating surface in service, laying the foundation for studying the thermal insulation effect of thermal barrier coatings, thereby accurately evaluating the thermal insulation performance of thermal barrier coatings.

[0117] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0118] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for determining the heat transfer coefficient of thermal barrier coatings. It is characterized in that include: Obtaining temperature information and thermal conductivity of the thermal barrier coating; the temperature information includes gas temperature, ceramic layer top temperature, ceramic layer bottom temperature, substrate temperature and cooling gas temperature; the ceramic layer top temperature is the temperature of the ceramic layer side close to the gas; the ceramic layer bottom temperature is the temperature of the ceramic layer side close to the bonding layer; the thermal conductivity includes the thermal conductivity of the ceramic and the thermal conductivity of the substrate; Determining a heat transfer coefficient of a thermal barrier coating according to the temperature information of the thermal barrier coating and the thermal conductivity; The heat transfer coefficient of the thermal barrier coating is used to determine the thermal insulation performance of the thermal barrier coating; Determining the heat transfer coefficient of the thermal barrier coating according to the temperature information of the thermal barrier coating and the thermal conductivity coefficient specifically includes: Determine the heat flux density equation of convective heat transfer between the fuel gas and the ceramic layer during the heat absorption process according to the fuel gas temperature and the top temperature of the ceramic layer using the convection heat transfer principle; Determine the heat flux density equation of the radiation heat exchange between the gas and the substrate during the heat absorption process according to the gas temperature and the top temperature of the ceramic layer using the radiation heat exchange principle; Determine the heat flux density equation of heat conduction of the ceramic layer during heat dissipation according to the top temperature of the ceramic layer, the bottom temperature of the ceramic layer and the thermal conductivity of the ceramic by using the heat conduction principle; Determine the heat flux density equation of the heat conduction of the substrate during the heat dissipation process according to the bottom temperature of the ceramic layer, the substrate temperature and the thermal conductivity of the substrate using the heat conduction principle; Determine the heat flux density equation of convection heat transfer during cooling in the heat dissipation process according to the substrate temperature and the cooling gas temperature based on the convection heat transfer principle; The heat transfer coefficient of the thermal barrier coating is determined according to the heat flux density equation for convective heat transfer between the fuel gas and the ceramic layer during the heat absorption process, the heat flux density equation for radiation heat transfer between the fuel gas and the substrate during the heat absorption process, the heat flux density equation for heat conduction of the ceramic layer during the heat dissipation process, the heat flux density equation for heat conduction of the substrate during the heat dissipation process, and the heat flux density equation for convective heat transfer during cooling during the heat dissipation process.

2. The method for determining the heat transfer coefficient of a thermal barrier coating according to claim 1, It is characterized in that The obtaining of the temperature information and thermal conductivity of the thermal barrier coating specifically includes: obtaining the gas temperature; Obtaining the top temperature of the ceramic layer using a colorimetric thermometer; Using a thin film thermocouple to obtain the bottom temperature of the ceramic layer; Obtaining the substrate temperature using a K-type thermocouple; The cooling gas temperature is obtained by using a three-point temperature measurement method; The thermal conductivity is measured using a laser flash method.

3. The method for determining the heat transfer coefficient of a thermal barrier coating according to claim 1, It is characterized in that The heat flux density equation for convective heat transfer between the fuel gas and the ceramic layer during the endothermic process is specifically: q 1 =h 1 (T g1 -T 1 ) Among them, q 1 is the heat flux density of convective heat transfer between the gas and the ceramic layer during the heat absorption process, h 1 is the convection heat transfer coefficient between the gas and the ceramic layer, T g1 is the gas temperature, T 1 is the top temperature of the ceramic layer.

4. The method for determining the heat transfer coefficient of a thermal barrier coating according to claim 1, It is characterized in that The heat flux density equation for the radiation heat exchange between the gas and the substrate during the endothermic process is specifically: Among them, q 2 The heat flux density of the radiation heat exchange between the gas and the substrate during the endothermic process, ε 1 is the matrix blackness, T g1 is the gas temperature, T 1 is the top temperature of the ceramic layer.

5. The method for determining the heat transfer coefficient of a thermal barrier coating according to claim 1, It is characterized in that The heat flux density equation of the heat conduction of the ceramic layer during the heat dissipation process is specifically: Among them, q 3 is the heat flux density of the ceramic layer during heat dissipation, λ c is the thermal conductivity of ceramics, T 1 is the top temperature of the ceramic layer, T 2 is the bottom temperature of the ceramic layer, δ c is the thickness of the ceramic layer.

6. The method for determining the heat transfer coefficient of a thermal barrier coating according to claim 1, It is characterized in that The heat flux density equation of the substrate heat conduction during the heat dissipation process is specifically: Among them, q 4 is the heat flux density of the substrate heat conduction during the heat dissipation process, λ s is the thermal conductivity of the matrix, δ s is the substrate thickness, T 2 is the bottom temperature of the ceramic layer, T 3 is the substrate temperature.

7. The method for determining the heat transfer coefficient of a thermal barrier coating according to claim 1, It is characterized in that The heat flux density equation of convection heat transfer during cooling in the heat dissipation process is specifically: q 5 =h 2 (T 3 -T a2 ) Among them, q 5 is the heat flux density of convection heat transfer during cooling in the heat dissipation process, h 2 is the convective heat transfer coefficient between the substrate and the cooling gas, T 3 is the substrate temperature, T a2 is the cooling gas temperature.

8. The method for determining the heat transfer coefficient of a thermal barrier coating according to claim 1, It is characterized in that The expression of the heat transfer coefficient of the thermal barrier coating is specifically: Among them, h 1 is the convection heat transfer coefficient between the gas and the ceramic layer, T g1 is the gas temperature, T 1 is the top temperature of the ceramic layer, ε 1 is the matrix blackness, λ c is the thermal conductivity of ceramics, T 2 is the bottom temperature of the ceramic layer, δ c is the thickness of the ceramic layer, T 3 is the substrate temperature, h 2 is the convective heat transfer coefficient between the substrate and the cooling gas, T a2 is the cooling gas temperature.

9. A system for determining the heat transfer coefficient of thermal barrier coatings. It is characterized in that include: An acquisition module is used to acquire temperature information and thermal conductivity of the thermal barrier coating; the temperature information includes the gas temperature, the top temperature of the ceramic layer, the bottom temperature of the ceramic layer, the substrate temperature and the cooling gas temperature; the top temperature of the ceramic layer is the temperature of the side of the ceramic layer close to the gas; the bottom temperature of the ceramic layer is the temperature of the side of the ceramic layer close to the bonding layer; the thermal conductivity includes the thermal conductivity of the ceramic and the thermal conductivity of the substrate; A thermal barrier coating heat transfer coefficient determination module, used to determine the thermal barrier coating heat transfer coefficient according to the temperature information of the thermal barrier coating and the thermal conductivity; The heat transfer coefficient of the thermal barrier coating is used to determine the thermal insulation performance of the thermal barrier coating; determining the heat transfer coefficient of the thermal barrier coating according to the temperature information of the thermal barrier coating and the thermal conductivity specifically includes: Determine the heat flux density equation of convective heat transfer between the fuel gas and the ceramic layer during the heat absorption process according to the fuel gas temperature and the top temperature of the ceramic layer using the convection heat transfer principle; Determine the heat flux density equation of the radiation heat exchange between the gas and the substrate during the heat absorption process according to the gas temperature and the top temperature of the ceramic layer using the radiation heat exchange principle; Determine the heat flux density equation of heat conduction of the ceramic layer during heat dissipation according to the top temperature of the ceramic layer, the bottom temperature of the ceramic layer and the thermal conductivity of the ceramic by using the heat conduction principle; Determine the heat flux density equation of the heat conduction of the substrate during the heat dissipation process according to the bottom temperature of the ceramic layer, the substrate temperature and the thermal conductivity of the substrate using the heat conduction principle; Determine the heat flux density equation of convection heat transfer during cooling in the heat dissipation process according to the substrate temperature and the cooling gas temperature based on the convection heat transfer principle; The heat transfer coefficient of the thermal barrier coating is determined according to the heat flux density equation for convective heat transfer between the fuel gas and the ceramic layer during the heat absorption process, the heat flux density equation for radiation heat transfer between the fuel gas and the substrate during the heat absorption process, the heat flux density equation for heat conduction of the ceramic layer during the heat dissipation process, the heat flux density equation for heat conduction of the substrate during the heat dissipation process, and the heat flux density equation for convective heat transfer during cooling during the heat dissipation process.

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