A method and system for separating and measuring the net radiation heat flux and convection heat flux of high-temperature components

Abstract

The present invention discloses a method and system for separately measuring the net radiation heat flux and convection heat flux of a high-temperature component, comprising: obtaining the wall temperature of a test piece through a wall temperature measurement test, and calculating the total heat flux based on the wall temperature of the test piece; obtaining mainstream parameters, and judging the mainstream parameters to obtain a temperature recovery coefficient; performing parameter transformation on the total heat flux based on the temperature recovery coefficient, obtaining the convection heat transfer coefficient, radiation temperature and radiation coefficient through ternary linear regression based on the parameter transformation result, and calculating the net radiation heat flux and convection heat flux based on the convection heat transfer coefficient, radiation temperature and radiation coefficient.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature component measurement, and in particular to a method and system for separately measuring the net radiation heat flux and convection heat flux of a high-temperature component. Background Art

[0002] Aircraft engines contain many high-temperature components, such as combustion chambers and turbine blades, which must withstand demanding operating temperatures exceeding 2000K, a temperature that continues to rise annually. Furthermore, these components employ complex cooling mechanisms, such as film cooling and impingement cooling, to keep component temperatures below the melting point of the material. This results in a significant temperature difference between the ambient temperature and the component surface, making thermal radiation a significant concern. Furthermore, the increased presence of radiatively active gases in engine combustion gases leads to more pronounced radiation effects. Net radiation heat flux is used industrially to assess the impact of ambient radiation and improve understanding of the thermal radiation environment of high-temperature components. It can assess radiation values ​​in any environment and compare radiation heat flux before and after component optimization. This parameter effectively guides the optimization design of structural parameters for high-temperature components. However, thermal radiation involves absorption, emission, reflection, transmission, and scattering, and the discontinuous radiation spectrum of gases makes the integral-differential form of the radiation transfer equation difficult to solve.

[0003] Currently, the net radiative heat flux of high-temperature components is typically calculated using numerical simulations, simplified discrete solutions to the radiation transfer equation, or neglected. However, due to the difficulty in obtaining accurate information such as the gas absorption coefficient and the location of the radiation source, these methods significantly simplify the radiation environment and fail to fully reflect the actual radiation source. This makes it difficult to accurately decouple the radiative and convective heat fluxes of high-temperature components, leading to a series of design issues such as under- or over-protection. To improve the accuracy of heat transfer design for high-temperature components, there is an urgent need to develop a method that can directly and effectively decouple the radiative and convective heat fluxes of high-temperature components and separate the measurements. Summary of the Invention

[0004] To solve the problems existing in the above-mentioned prior art, the present invention provides a method and system for separately measuring the net radiation heat flux and convection heat flux of high-temperature components, which can reflect the actual radiation environment of high-temperature components and improve the heat transfer design accuracy of high-temperature components.

[0005] In order to achieve the above technical objectives, the present invention provides the following technical solutions:

[0006] A method for separately measuring the net radiation heat flux and the convection heat flux of a high-temperature component, comprising:

[0007] The wall temperature of the test piece is obtained through the wall temperature measurement test, and the total heat flux is calculated based on the wall temperature of the test piece; the mainstream parameters are obtained and the temperature recovery coefficient is obtained by judging the mainstream parameters; the total heat flux is parameterized based on the temperature recovery coefficient, and the convective heat transfer coefficient, radiation temperature and radiation coefficient are obtained through ternary linear regression based on the parameter transformation results. The net radiation heat flux and convective heat flux are calculated based on the convective heat transfer coefficient, radiation temperature and radiation coefficient.

[0008] Optionally, the wall temperature measurement experiment process includes: keeping the mainstream flow rate and mainstream temperature unchanged, changing the cooling air temperature, and recording the temperatures of corresponding measuring points above and below the test piece during the process of changing the cooling air temperature to obtain the wall temperature of the test piece.

[0009] Optionally, the process of calculating the total heat flow includes:

[0010]

[0011] Among them, q tot is the total heat flow, λ is the thermal conductivity, d is the distance between the upper and lower measuring points, T w is the temperature of the test point on the test piece, T w,down is the temperature of the test point under the test piece.

[0012] Optionally, mainstream parameters include Mach number, Reynolds number and critical Reynolds number.

[0013] Optionally, the process of calculating the net radiation heat flux and the convective heat flux includes:

[0014]

[0015]

[0016] Among them, q rad is the net radiation heat flux, q conv is the convective heat flux, r is the emissivity, σ is the Stefan-Boltzmann constant, T is the radiation temperature, h cp is the convective heat transfer coefficient calculated based on the mainstream temperature, T ∞ is the mainstream temperature, R is the temperature recovery coefficient, C p is the specific heat at constant pressure, u ∞ is the mainstream flow velocity, and n is the empirical parameter of temperature ratio.

[0017] In order to better achieve the above technical objectives, the present invention also provides a system for separating and measuring the net radiation heat flux and convection heat flux of high-temperature components, comprising: an acquisition module and a processing module;

[0018] The acquisition module is used to obtain the wall temperature of the test piece through a wall temperature measurement test, calculate the total heat flow based on the wall temperature of the test piece; obtain the mainstream parameters, and judge the mainstream parameters to obtain the temperature recovery coefficient;

[0019] The processing module performs parameter transformation on the total heat flux based on the temperature recovery coefficient, obtains the convective heat transfer coefficient, radiation temperature and radiation coefficient through ternary linear regression based on the parameter transformation results, and calculates the net radiation heat flux and convective heat flux based on the convective heat transfer coefficient, radiation temperature and radiation coefficient.

[0020] Optionally, in the acquisition module, the wall temperature measurement experiment process includes: keeping the mainstream flow velocity and mainstream temperature unchanged, changing the cooling air temperature, and recording the temperatures of the corresponding measuring points above and below the test piece during the process of changing the cooling air temperature to obtain the wall temperature of the test piece.

[0021] Optionally, in the acquisition module, the process of calculating the total heat flow includes:

[0022]

[0023] Among them, q tot is the total heat flow, λ is the thermal conductivity, d is the distance between the upper and lower measuring points, T w is the temperature of the test point on the test piece, T w,down is the temperature of the test point under the test piece.

[0024] Optionally, in the acquisition module: mainstream parameters include Mach number, Reynolds number and critical Reynolds number.

[0025] Optionally, in the processing module, the process of calculating the net radiation heat flux value and the convective heat flux value includes:

[0026]

[0027]

[0028] Among them, q rad is the net radiation heat flux, q conv is the convective heat flux, r is the emissivity, σ is the Stefan-Boltzmann constant, T is the radiation temperature, h cp is the convective heat transfer coefficient calculated based on the mainstream temperature, T ∞ is the mainstream temperature, R is the temperature recovery coefficient, C p is the specific heat at constant pressure, u ∞ is the mainstream flow velocity, and n is the empirical parameter of temperature ratio.

[0029] The present invention has the following technical effects:

[0030] This paper proposes a method and system for measuring the net radiative heat flux and convective heat flux of high-temperature components. This method, which takes into account the complex thermal radiation effects of a real high-temperature environment, directly decouples the radiative heat flux and convective heat flux of high-temperature components, effectively and accurately separating and measuring them. This improves the accuracy of heat transfer calculations between the high-temperature environment and the components. This method addresses the difficulty in measuring and evaluating the radiative heat flux of high-temperature components, avoiding a series of design issues such as "underprotection" or "overprotection." Based on these parameters, it further improves the heat transfer design accuracy of high-temperature components, particularly aircraft engine turbine blades. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. 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 any creative work.

[0032] Figure 1 A schematic diagram of a method flow chart provided in an embodiment of the present invention;

[0033] Figure 2 Schematic diagram of the arrangement of upper and lower measuring points for the test provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0035] In order to solve the problems existing in the prior art, the present invention provides the following solutions:

[0036] Example 1

[0037] like Figure 1 As shown, the present invention provides a method for separately measuring the net radiation heat flux and convective heat flux of high-temperature components. This method can improve the calculation accuracy of heat exchange heat flux and guide the structural design of high-temperature components and the optimization of radiation environment parameters. By changing the high-temperature environment parameters and the high-temperature component structure, this method can quantify the extent to which the improved design reduces the thermal radiation load, thereby improving the component design accuracy. In addition, this method obtains the convective heat flux that excludes the thermal radiation heat flux, which can improve the calculation accuracy of heat exchange heat flux, thereby improving the cooling structure and heat transfer design accuracy of high-temperature components.

[0038] The above method specifically includes:

[0039] First, high-temperature testing was performed to determine the mainstream temperature, the wall temperature of n groups of test specimens, and the total heat flux. Secondly, the specific value of the temperature recovery coefficient was determined. Finally, a series of parameter transformations and three-variable linear regression were used to separate the net radiative heat flux and convective heat flux flowing into the test specimen. This separation of radiative and convective heat flux improves the accuracy of heat flux calculations between the high-temperature environment and the component. Based on the actual use of these parameters, the cooling structure and heat transfer design accuracy of the high-temperature component can be improved.

[0040] The test and calculation method of the present invention improves the accuracy of heat transfer calculations between high-temperature environments and components by separating radiative heat flux from convective heat flux. This method fully reflects the actual radiation environment of high-temperature components, solving the problem of difficulty in evaluating radiative heat flux of high-temperature components. Furthermore, based on the actual use of the above parameters, it further improves the heat transfer design accuracy of high-temperature components, especially aircraft engine turbine blades, and has broad prospects for engineering applications. The specific steps are as follows:

[0041] Step 1: Carry out the wall temperature measurement test of the test piece in a high temperature environment, maintaining the mainstream flow parameter u ∞ and temperature T ∞ No change, change the air conditioning temperature T cold , n groups of cooling air temperature conditions are T cold_1 ,T cold_2 ,…,T cold_n .

[0042] Step 1 specifically includes:

[0043] The difference between the lowest and highest cooling air temperatures in the n groups of working conditions should be as large as possible to include a wider range of independent variables and improve the accuracy of the calculation.

[0044] Step 2: Measure the mainstream flow velocity u ∞ and mainstream temperature T ∞ ,like Figure 2 As shown, the temperature of the upper and lower corresponding measuring points of n groups of cold air temperature condition test pieces (T w_1 ,T w,down_1 ),(T w_2 ,T w,down_2 ),…,(T w_n ,T w,down_n ), and calculate the total heat flow q into the measuring point tot , we get (T w_1 ,q tot_1 ),(T w_2 ,q tot_2 ),…,(T w_n ,q tot_n ).

[0045] Step 2 specifically includes:

[0046] Total heat flow into the measuring point q tot The calculation method is as follows:

[0047]

[0048] Where λ is the thermal conductivity and d is the distance between the upper and lower measuring points.

[0049] Step 3: Calculate the mainstream Mach number Ma and Reynolds number Re g and critical Reynolds number Re cr , if Ma<0.3, the temperature recovery coefficient R=0; if Ma>0.3 and Re g <Re cr (Mainstream flow state is high speed and laminar flow), temperature recovery coefficient (Pr is the Prandtl number); if Ma>0.3 and Re g >Re cr (mainstream flow state is high speed and turbulent), temperature recovery coefficient

[0050] Step 3 specifically includes:

[0051] Mach number calculation formula:

[0052]

[0053] Where v is the flow velocity and c is the speed of sound.

[0054] Reynolds number calculation formula:

[0055]

[0056] Where ρ is the density, d is the characteristic size, and μ is the dynamic viscosity.

[0057] Step 4: respectively obtain (T w_1 ,q tot_1 ),(T w_2 ,q tot_2 ),…,(T w_n ,q tot_n ) to perform parameter transformation and obtain n sets of variable data sets (X1, X2, Y) to be determined. The transformation form is as follows:

[0058]

[0059]

[0060] r'=r·T 4

[0061] Where σ is the Stefan-Boltzmann constant, Cp is the specific heat at constant pressure, u ∞ is the mainstream flow velocity, n is the temperature ratio empirical parameter, n = -(0.129 + 0.171·T w / T ∞ ), r is the emissivity, T is the radiation temperature, and r' is the radiation parameter.

[0062] Step 5: Transform the total heat flow equation Transformed into the following form:

[0063] Y=r'·X1-r·X2+h cp

[0064] Step 6: For the n sets of data sets (X1, X2) with (X1, X2) as independent variables and Y as dependent variable, calculate them according to the formula Y = r'·X1-r·X2+h cp The three-variable linear regression is performed in the form of (r, r', h cp ), h cp is the convective heat transfer coefficient calculated based on the mainstream temperature, and T is obtained using the following formula:

[0065]

[0066] Step 7: Use the following formula to obtain the specific values ​​of the net radiation heat flux and convection heat flux of the test piece in the high temperature environment:

[0067]

[0068]

[0069] Among them, q rad is the net radiation heat flux, q conv is the convective heat flux, r is the emissivity, σ is the Stefan-Boltzmann constant, T is the radiation temperature, h cp is the convective heat transfer coefficient calculated based on the mainstream temperature, T ∞ is the mainstream temperature, R is the temperature recovery coefficient, C p is the specific heat at constant pressure, u ∞ is the mainstream flow velocity.

[0070] The present invention takes into account the complex thermal radiation effects of real high-temperature environments, avoids the direct calculation of the incident radiation heat flux that is difficult to obtain, solves the problem of difficult measurement and evaluation of the radiation heat flux of high-temperature components, improves the heat transfer design accuracy of high-temperature components, especially aircraft engine turbine blades, and has a relatively broad engineering application prospect.

[0071] Example 2

[0072] In order to better achieve the above technical objectives, the present invention also provides a system for separating and measuring the net radiation heat flux and convection heat flux of high-temperature components, comprising: an acquisition module and a processing module;

[0073] The acquisition module is used to obtain the wall temperature of the test piece through a wall temperature measurement test, calculate the total heat flow based on the wall temperature of the test piece; obtain the mainstream parameters, and judge the mainstream parameters to obtain the temperature recovery coefficient;

[0074] The processing module performs parameter transformation on the total heat flux based on the temperature recovery coefficient. Based on this parameter transformation, a three-variable linear regression is performed to determine the convective heat transfer coefficient, radiation temperature, and emissivity. The net radiation heat flux and convective heat flux values ​​are calculated based on these factors. This system corresponds to the aforementioned method and will not be further elaborated here.

[0075] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for measuring the net radiation heat flux and convection heat flux of a high-temperature component separately, characterized in that: include: The wall temperature of the test piece is obtained through a wall temperature measurement test, and the total heat flow is calculated based on the wall temperature of the test piece; Obtain mainstream parameters and determine the temperature recovery coefficient based on the mainstream parameters; Performing parameter transformation on the total heat flux based on the temperature recovery coefficient, obtaining the convective heat transfer coefficient, the radiation temperature, and the radiation coefficient through ternary linear regression based on the parameter transformation result, and calculating the net radiation heat flux and the convective heat flux based on the convective heat transfer coefficient, the radiation temperature, and the radiation coefficient; The process of calculating the net radiation heat flux and the convective heat flux includes: ； in, is the net radiative heat flux, is the convective heat flow, is the radiation coefficient, is the Stefan-Boltzmann constant, is the radiation temperature, is the convective heat transfer coefficient calculated based on the mainstream temperature, is the mainstream temperature, is the temperature recovery coefficient, C p is the specific heat at constant pressure, u ∞ is the mainstream flow velocity, n is the temperature ratio empirical parameter, T w is the temperature of the measuring point on the test piece.

2. The method according to claim 1, wherein: The wall temperature measurement test process includes: keeping the mainstream flow rate and mainstream temperature unchanged, changing the cooling air temperature, and recording the temperatures of corresponding measuring points above and below the test piece during the cooling air temperature change to obtain the wall temperature of the test piece.

3. The method according to claim 1, wherein: The process of calculating the total heat flow includes: in, q tot is the total heat flow, λ is the thermal conductivity, d is the distance between the upper and lower measuring points, T w is the temperature of the test point on the test piece, T w,down is the temperature of the test point under the test piece.

4. The method according to claim 1, wherein: The mainstream parameters include Mach number, Reynolds number and critical Reynolds number.

5. A system for measuring the net radiation heat flux and convection heat flux of a high-temperature component based on any one of claims 1 to 4, characterized in that: include: Acquisition module and processing module; The acquisition module is used to obtain the wall temperature of the test piece through a wall temperature measurement test, calculate the total heat flow based on the wall temperature of the test piece; obtain the mainstream parameters, and determine the mainstream parameters to obtain the temperature recovery coefficient; The processing module performs parameter transformation on the total heat flow based on the temperature recovery coefficient, obtains the convective heat transfer coefficient, the radiation temperature and the radiation coefficient through ternary linear regression based on the parameter transformation result, and calculates the net radiation heat flow and the convective heat flow based on the convective heat transfer coefficient, the radiation temperature and the radiation coefficient.

6. The system according to claim 5, characterized in that: In the acquisition module, the wall temperature measurement test process includes: keeping the mainstream flow rate and mainstream temperature unchanged, changing the cooling air temperature, and recording the temperatures of the corresponding measuring points above and below the test piece during the process of changing the cooling air temperature to obtain the wall temperature of the test piece.

7. The system according to claim 5, characterized in that: In the acquisition module, the process of calculating the total heat flow includes: in, q tot is the total heat flow, λ is the thermal conductivity, d is the distance between the upper and lower measuring points, T w is the temperature of the test point on the test piece, T w,down is the temperature of the test point under the test piece.

8. The system according to claim 5, characterized in that: In the acquisition module: the mainstream parameters include Mach number, Reynolds number and critical Reynolds number.

9. The system according to claim 5, characterized in that: In the processing module, the process of calculating the net radiation heat flux value and the convective heat flux value includes: ； in, is the net radiative heat flux, is the convective heat flow, is the radiation coefficient, is the Stefan-Boltzmann constant, is the radiation temperature, is the convective heat transfer coefficient calculated based on the mainstream temperature, is the mainstream temperature, is the temperature recovery coefficient, C p is the specific heat at constant pressure, u ∞ is the mainstream flow velocity, n is the temperature ratio empirical parameter, T w is the temperature of the measuring point on the test piece.

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