High-efficiency measurement system and method for thermal radiation characteristics of materials with different thicknesses in high-temperature infrared hoods

Abstract

The invention relates to a high-efficiency measurement system and method for the thermal radiation characteristics of materials of different thicknesses in a high-temperature infrared hood, and belongs to the field of thermal radiation measurement technology. This invention aims to address the problem of overlapping reconstruction results due to the significant influence of the thickness of the material to be measured and measurement errors in existing numerical simulation methods. The invention divides the infrared hood specimen into equal parts along the direction of radiation transmission, and according to the radiation transmission principle and the energy conservation relationship, sequentially obtains the total radiation passing through the first layer, the first to second layers, and so on, and the first to n layers of the hood material. Subsequently, based on the energy method, the algebraic relationship between the transmittance and self-radiation of the infrared hood material with a thickness of Δ and a temperature of T and the transmittance and self-radiation of the entire infrared detection hood is deduced. Thermal radiation characteristics such as transmittance and self-radiation of an infrared hood with a thickness of x are experimentally measured, and the thermal radiation characteristic data of the material per unit thickness is calculated based on the algebraic relationship. This invention is mainly used to obtain the thermal radiation characteristics of the infrared hood.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal radiation measurement, and in particular relates to a method for measuring thermal radiation characteristics of materials of different thicknesses of a high-temperature infrared hood. Background Art

[0002] When an aircraft flies at hypersonic speeds within the atmosphere, the high-temperature infrared hood quickly becomes the primary factor in the aerodynamic thermal radiation effect of the infrared detection system. High temperatures increase the infrared hood's own thermal radiation, with radiation from the hood's surface primarily concentrated in the infrared band. The high-temperature shock wave gases and the hood produce a strong aerodynamic thermal radiation effect, which interferes with the detector and the target's infrared signal, increasing the detector's background brightness and reducing the target's detection signal-to-noise ratio. This degrades the system's ability to detect and track targets, and can even lead to infrared detector saturation, making it unable to accurately distinguish signals from the target. This weakens the target's detection, tracking, and identification capabilities, and reduces the imaging quality of the infrared detection system.

[0003] At present, measurement research on infrared hood materials is mostly focused on physical and chemical properties such as strength, hardness, melting point, refractive index, thermal conductivity and corrosion resistance, while there is less research on thermal radiation transmission characteristics such as transmittance and attenuation coefficient, and even less data on high-temperature states. This has affected and even restricted the development of research on the aerodynamic thermal radiation effects of high-temperature infrared optical windows, hindering the application of infrared detection systems in the field of hypersonic aircraft.

[0004] Traditional infrared hood radiation characteristic testing methods require one or more repeated experiments for the same material when the material thickness changes. The temperature and other environmental conditions cannot be guaranteed to be completely consistent between experiments, resulting in large errors between the measured and true values ​​of the infrared hood material radiation characteristics and additional experimental costs. Traditional approaches use numerical simulation methods, including the discrete coordinate method and the finite volume method, to simulate the actual situation. Combined with the apparent radiation intensity measurement results at different angles, the radiation characteristic fields inside the medium, such as the absorption coefficient field and the refractive index field, are inverted and reconstructed. The reconstruction process is significantly affected by measurement errors, and the accuracy of the reconstruction decreases as the thickness of the medium increases. Therefore, there is an urgent need for a method to achieve a one-time measurement of the thermal radiation characteristics of infrared hood materials of different thicknesses under high temperature conditions, so as to more efficiently establish a quantitative model of the transmission characteristics of high-temperature infrared hoods. Summary of the Invention

[0005] The present invention aims to solve the problem of overlapping reconstruction results due to the influence of the thickness of the material to be measured and the measurement error in the existing numerical simulation method.

[0006] An efficient measurement system for the thermal radiation characteristics of high-temperature infrared hoods of different thickness materials, including a Fourier transform infrared spectrometer, a heating furnace, a blackbody furnace, a temperature control inspection instrument, and a data acquisition and processing system;

[0007] During measurement, the center of the Fourier transform infrared spectrometer's detection lens, the center of the heating furnace, and the center of the blackbody furnace cavity are set on the same horizontal line;

[0008] The blackbody furnace is used to emit blackbody infrared radiation. During the measurement process, the blackbody furnace is adjusted to change the blackbody temperature to emit infrared radiation at different blackbody temperatures.

[0009] The heating furnace is used to heat the infrared hood sample. During the measurement process, the temperature of the heating furnace is adjusted to provide different temperatures for the infrared hood sample material.

[0010] Temperature control patrol instrument, used to detect and control the temperature inside the heating furnace;

[0011] Fourier infrared spectrometer, used to obtain blackbody infrared radiation through the infrared hood;

[0012] The data acquisition and processing system is used to collect data from the Fourier infrared spectrometer and the temperature control patrol meter, and use the signal obtained by the Fourier infrared spectrometer to calculate the apparent radiation intensity of the normal phase spectrum of the material at the temperature displayed by the temperature control patrol meter.

[0013] A high-efficiency measurement method for the thermal radiation characteristics of materials of different thicknesses of a high-temperature infrared hood comprises the following steps:

[0014] Step 1: Build the high-efficiency measurement system for thermal radiation characteristics of high-temperature infrared hoods with different thicknesses of materials as described in claim 1;

[0015] Step 2: In the initial stage, do not start the heating furnace, do not place any samples in the heating furnace, start the blackbody furnace, and set the blackbody furnace temperature to T b , use Fourier infrared spectrometer to obtain the infrared radiation L of the black body obj ;

[0016] Step 3: Place the infrared hood sample in a high-temperature heating furnace and heat it until the temperature of the infrared hood sample material reaches the specified temperature T win After the distribution is uniform, the infrared radiation L transmitted through the infrared hood sample material is obtained using an infrared detector. tot ;

[0017] Step 4: Control the temperature of the sample material to keep it at T win unchanged, change the blackbody temperature T b In this state, repeat steps 2 and 3 to obtain multiple sets of blackbody temperatures T b,i Infrared radiation L in the state obj,i and L tot,i ; where subscript i represents the i-th measurement;

[0018] Step 5: When the temperature of the material remains unchanged, its radiation characteristic parameters are fixed values. By statistically analyzing the test results, the least squares method is used to fit multiple sets of blackbody temperatures T b,i Infrared radiation L in the state obj,i and L tot,i , and then the temperature T win Transmittance τ of uniformly distributed infrared hood sample material T,win and self-radiation L T,win ;

[0019] Step 6: Divide the infrared hood sample into n equal layers along the thickness direction, and obtain the apparent spectral transmittance of the infrared hood sample material per unit thickness Δ according to the energy conservation relationship. Self-radiation Based on Obtain the apparent normal spectral emissivity

[0020] Step 7: According to the inverse radiation transfer problem solving algorithm, assuming that the refractive index of the infrared hood sample material is The absorption coefficient is The apparent spectral radiation intensity at any angle on the exit interface of the infrared hood sample material is calculated by solving the radiation transfer equation. Apparent normal spectral emissivity estimate and the apparent spectral transmittance estimate

[0021] Step 8: The apparent normal spectral emissivity of the infrared hood sample material obtained in step 6 and apparent spectral transmittance And the estimated value of the apparent normal emissivity of the infrared hood sample material obtained in step 7 Apparent spectral transmittance estimate Substitute the following objective function calculation formula to calculate the objective function value F obj ;

[0022]

[0023] Step 9: Determine the objective function value F in step 8 obj Is it less than the set threshold ξ?

[0024] If so, the refractive index of the infrared hood sample material assumed in step 8 is Absorption coefficient That is, the real refractive index and absorption coefficient of the infrared hood sample material;

[0025] If not, return to step 7 and update the refractive index of the infrared hood sample material according to the inverse problem algorithm. Absorption coefficient Reset the refractive index and absorption coefficient of the infrared hood sample material and recalculate until the objective function value F in step eight is obj is less than the set threshold ξ, and the true refractive index of the infrared hood sample material is obtained. Absorption coefficient

[0026] Combined with step 6, the temperature is now T win The self-radiation of the sample material Refractive index Absorption coefficient

[0027] Step 10: Change the temperature T of the sample material win Repeat steps 2 to 9 to obtain different temperatures T win,j Under the condition of unit thickness Δ, the refractive index of the infrared hood sample material is Absorption coefficient With its own radiation Where the subscript j indicates the jth group of measurements;

[0028] The self-radiation of the infrared hood sample material in different directions per unit thickness Δ is obtained by calculation

[0029] Through different temperatures T win,j The refractive index of the sample material under Absorption coefficient With its own radiation Establish a database of radiation properties of infrared hood materials with unit thickness Δ at different temperatures;

[0030] Step 11: Using the idea of ​​physical discreteness, divide the infrared hood to be tested into m layers of thin layers with a thickness of Δ; use an infrared thermal imager to measure the temperature of each thin layer of the infrared hood under the working condition to be tested, and record it as T win,k , where the subscript k = 1, 2, …, m, represents the kth thin layer; the temperature field of the infrared hood is established based on the measurement results, and the radiation physical property database of the infrared hood materials with different temperature unit thickness Δ established in step 10 is queried to obtain the refractive index, absorption coefficient, self-radiation distribution field and radiation distribution field in different directions of each infrared hood thin layer; then the refractive index and absorption coefficient at different positions in the infrared hood are obtained, and the directional radiation intensity and directional emissivity of the infrared hood to be measured are obtained by superposition along the thickness direction.

[0031] Beneficial effects:

[0032] Traditional calculation methods discretize the infrared optical window under test at the model level, but these methods are affected by the thickness of the material under test and measurement errors. Therefore, the present invention takes a different approach by discretizing the material at the physical level, dividing it into several thin layers of relatively small thickness. The transmittance and self-radiation of these layers are measured, and an inverse radiation transmission problem calculation method is introduced to invert and reconstruct the material's radiation properties, such as the absorption coefficient and refractive index. In this case, because the inverted and reconstructed model is relatively thin, the reconstruction results are highly accurate.

[0033] The present invention also provides a method for measuring the thermal radiation characteristics of infrared hoods of varying material thicknesses, such as transmittance and self-radiation, based on the infrared hood's target characteristic transmission mechanism, without requiring repeated experiments. Specifically, when establishing a quantitative model for infrared hood transmission characteristics, a database of the radiation properties of infrared hood materials per unit thickness is established based on the refractive index, absorption coefficient, and self-radiation of sample materials at different temperatures. This allows the thermal radiation characteristics of infrared hoods of varying material thicknesses to be determined without repeated experiments. This provides key data support for evaluating the impact of missile launch conditions on infrared detection images and information processing, resulting in more realistic infrared detection simulation images and facilitating the design and optimization of hypersonic flight infrared detection systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of an efficient measurement system for thermal radiation characteristics of high-temperature infrared hood materials of different thicknesses. DETAILED DESCRIPTION

[0035] The working principle of the present invention will be further described in detail below with reference to the accompanying drawings.

[0036] Specific implementation method 1: Combination Figure 1 To explain this embodiment,

[0037] This embodiment is a high-efficiency measurement system for the thermal radiation characteristics of materials of different thicknesses of a high-temperature infrared hood, comprising a Fourier transform infrared spectrometer 1, a heating furnace 2, a blackbody furnace 3, a temperature control inspection instrument 4, and a data acquisition and processing system 5;

[0038] When working, the center of the detection lens of the Fourier transform infrared spectrometer, the center of the heating furnace and the center of the blackbody furnace cavity are set on the same horizontal line;

[0039] The blackbody furnace is used to emit blackbody infrared radiation. During the measurement process, the blackbody furnace is adjusted to change the blackbody temperature to emit infrared radiation at different blackbody temperatures.

[0040] The heating furnace is used to heat the infrared hood sample. During the measurement process, the temperature of the heating furnace is adjusted to provide different temperatures for the infrared hood sample material.

[0041] Temperature control patrol instrument, used to detect and control the temperature inside the heating furnace;

[0042] Fourier infrared spectrometer, used to obtain blackbody infrared radiation through the infrared hood;

[0043] The data acquisition and processing system is used to collect data from the Fourier infrared spectrometer and the temperature control patrol meter, and use the signal obtained by the Fourier infrared spectrometer to calculate the apparent radiation intensity of the normal phase spectrum of the material at the temperature displayed by the temperature control patrol meter.

[0044] In this embodiment,

[0045] The Fourier transform infrared spectrometer was a FTIR-6100 Fourier transform infrared spectrometer, and its main specifications were: (1) the highest spectral resolution was 0.022 nm; (2) the scanning spectral range was 1.25-25; (3) the scanning frequency was 20 Hz; and (4) the signal-to-noise ratio was 50,000 / 1.

[0046] The heating furnace is an SGM.M6 / 14AE double-door furnace with a chamber depth, width, and height of 230 x 180 x 150 mm. Heating power is 4 kW, and the heating elements are silicon-molybdenum rods. The maximum temperature is 1700°C, with a temperature stability of ±1°C and a temperature uniformity of ±6°C. The temperature rises from room temperature to 1400°C in 45-50 minutes.

[0047] The blackbody furnace is RT1500 type blackbody furnace, and its main parameters are: maximum temperature 1450℃, effective emissivity 0.99, radiation aperture φ50, temperature range: 0-1450℃ can be set arbitrarily, temperature control accuracy ±0.5℃, stability 1℃ / 3min, heating time: no more than 1 hour from room temperature to 1450℃. Specific implementation method 2:

[0049] This embodiment provides an efficient method for measuring the thermal radiation characteristics of materials of different thicknesses of a high-temperature infrared hood, including the following steps:

[0050] Step 1: Build an efficient measurement system for the thermal radiation characteristics of high-temperature infrared hood materials of different thicknesses.

[0051] Step 2: In the initial stage, do not start the heating furnace, do not place any samples in the heating furnace, start the blackbody furnace, and set the blackbody furnace temperature to T b , use Fourier infrared spectrometer to obtain the infrared radiation L of the black body obj .

[0052] Step 3: Place the infrared hood sample in a high-temperature heating furnace and heat it until the temperature of the infrared hood sample material reaches the specified temperature T winAfter the distribution is uniform, the infrared radiation L transmitted through the infrared hood sample material is obtained using an infrared detector. tot ;

[0053] Infrared head cover material is infrared optical window material;

[0054] Step 4: Control the temperature of the sample material to keep it at T win unchanged, change the blackbody temperature T b In this state, repeat steps 2 and 3 to obtain multiple sets of blackbody temperatures T b,i Infrared radiation L in the state obj,i and L tot,i ; where the subscript i represents the i-th measurement.

[0055] Step 5: When the temperature of the material remains unchanged, its radiation characteristic parameters are fixed values. Therefore, the least squares method can be used to fit multiple sets of blackbody temperatures T by statistics of the test results. b,i Infrared radiation L in the state obj,i and L tot,i , and then the temperature T win Transmittance τ of uniformly distributed infrared hood sample material T,win and self-radiation L T,win .

[0056] Step 6: Divide the infrared hood sample into n equal layers along the thickness direction, and obtain the apparent spectral transmittance of the infrared hood sample material per unit thickness Δ according to the energy conservation relationship. Self-radiation Based on Obtain the apparent normal spectral emissivity

[0057] The apparent normal spectral emissivity can be calculated by the following formula

[0058]

[0059] Where, L T,b Indicates that the temperature is the same as the temperature of the sample material per unit thickness, that is, the temperature is T win The intensity of blackbody radiation.

[0060] Step 7: According to the inverse radiation transfer problem solving algorithm, assuming that the refractive index of the infrared hood sample material is The absorption coefficient is The apparent spectral radiation intensity at any angle on the exit interface of the infrared hood sample material is calculated by solving the radiation transfer equation. Apparent normal spectral emissivity estimate and the apparent spectral transmittance estimate

[0061] Step 8: The apparent normal spectral emissivity of the infrared hood sample material obtained in step 6 and apparent spectral transmittance And the estimated value of the apparent normal emissivity of the infrared hood sample material obtained in step 7 Apparent spectral transmittance estimate Substitute the following objective function calculation formula to calculate the objective function value F obj ;

[0062]

[0063] Step 9: Determine the objective function value F in step 8 obj Is it less than the set threshold ξ?

[0064] If so, the refractive index of the infrared hood sample material assumed in step 8 is Absorption coefficient That is, the real refractive index and absorption coefficient of the infrared hood sample material;

[0065] If not, return to step 7 and update the refractive index of the infrared hood sample material according to the inverse problem algorithm. Absorption coefficient Reset the refractive index and absorption coefficient of the infrared hood sample material and recalculate until the objective function value F in step eight is obj is less than the set threshold ξ, and the true refractive index of the infrared hood sample material is obtained. Absorption coefficient Combined with step 6, the temperature is now T win The self-radiation of the sample material Refractive index Absorption coefficient

[0066] Step 10: Change the temperature T of the sample material win Repeat steps 2 to 9 to obtain different temperatures T win,j Under the condition of unit thickness Δ, the refractive index of the infrared hood sample material is Absorption coefficient With its own radiation The subscript j represents the jth set of measurements.

[0067] The self-radiation of the infrared hood sample material in different directions per unit thickness Δ can be obtained by calculation (The radiation intensity in different directions introduced here is obtained by calculation of refractive index and absorption coefficient, not by measurement.) win,j The refractive index of the sample material under Absorption coefficient With its own radiation Establish a radiation property database of infrared hood materials with unit thickness Δ at different temperatures.

[0068] Step 11: Using the idea of ​​physical discreteness, divide the infrared hood to be tested into m layers of thin layers with a thickness of Δ. Use an infrared thermal imager to measure the temperature of each thin layer of the infrared hood under the test conditions, and record it as T win,k , where the subscript k = 1, 2, …, m, represents the kth thin layer. Based on the measurement results, the temperature field of the infrared hood is established. By querying the radiation property database of infrared hood materials with different unit thicknesses Δ at different temperatures established in step 10, the refractive index, absorption coefficient, self-radiation distribution field, and radiation distribution field in different directions of each infrared hood thin layer can be obtained. Furthermore, the refractive index and absorption coefficient at different locations within the infrared hood can be obtained. By superimposing the data along the thickness direction, the directional radiation intensity and directional emissivity of the infrared hood under test can be obtained. Specific implementation method three:

[0070] This embodiment is a high-efficiency measurement method for the thermal radiation characteristics of high-temperature infrared hood materials of different thicknesses. Step 6 obtains the apparent spectral transmittance of the infrared hood sample material per unit thickness Δ. Self-radiation The process includes the following steps:

[0071] The infrared radiation L of the infrared hood material measured by the infrared detection system (the system in the Fourier transform infrared spectrometer) tot is the radiance L of the inner surface of the material λ (s), the target infrared radiation L reaching the outer surface of the infrared hood sample obj And the infrared hood's own radiation L win The joint effect is

[0072] L tot =L obj τ win +L win (3)

[0073] Where, τ win is the transmittance of the infrared optical window.

[0074] The radiation transfer equation is used to describe the transmission process of the target radiation energy through the infrared hood specimen. The energy is conserved along the radiation transmission direction. The infrared hood material is divided into n equal layers. It is deduced that there is a fixed algebraic relationship between the transmittance and self-radiation of the infrared hood material per unit thickness and the transmittance and self-radiation of the entire infrared hood. Based on the obtained algebraic relationship, the transmittance, attenuation coefficient and other thermal radiation characteristic data of infrared hood materials with different thicknesses under the same temperature and other working conditions can be directly calculated.

[0075] In order to achieve this purpose, the technical solution adopted by the present invention is: the infrared hood sample is divided into n layers along the thickness direction, assuming that the temperature T of the infrared optical window is uniformly distributed and the apparent spectral transmittance of each layer is and self-radiation Isotropic, according to the radiation transmission principle and energy conservation relationship, the total radiation passing through the first layer of infrared hood material can be obtained as

[0076]

[0077] The infrared radiation passing through the 1st and 2nd layers is

[0078]

[0079] Similarly, the total radiation passing through the 1st to nth layers, that is, the total radiation passing through the entire infrared hood, is

[0080]

[0081] Then, the apparent spectral transmittance of the infrared hood material with a thickness of Δ and a temperature of T can be deduced by the energy method. and self-radiation and the transmittance τ of the entire infrared detection infrared hood T,win and self-radiation L T,win The algebraic relationship between

[0082]

[0083]

[0084] By measuring the transmittance and infrared radiation characteristics of the infrared hood with a thickness of x, the thermal radiation characteristic data such as the apparent spectral transmittance and self-radiation of the infrared optical window material with a unit thickness of Δ are obtained.

[0085] Therefore, there is no need to repeat the experiment many times. The thermal radiation characteristic data of infrared optical window materials of other different thicknesses under the same temperature and other environmental conditions can be directly calculated based on the obtained algebraic relationship, and a quantitative model of the transmission characteristics of the infrared hood can be established. Specific implementation method four:

[0087] This embodiment is a method for efficiently measuring the thermal radiation characteristics of high-temperature infrared hood materials of different thicknesses. In step seven, the apparent spectral radiation intensity at any angle on the exit interface of the infrared hood sample material is calculated by solving the radiation transfer equation. Apparent normal spectral emissivity estimate and the apparent spectral transmittance estimate The process includes the following steps:

[0088] Assume that the temperature of the isotropic medium is Refractive index The absorption coefficient is Reflectivity The thickness of the medium is Δ; under one-dimensional conditions, when the medium is in a steady state and medium scattering is not considered, the radiation transfer equation can be simplified to:

[0089]

[0090] Solving the radiative transfer equation yields:

[0091]

[0092]

[0093] in, represents forward radiation, represents backward radiation; θ is the angle between the forward radiation and the backward radiation and the surface normal respectively;

[0094] At the internal boundary x = 0, the radiation intensity propagating in the positive direction includes the part of the radiation intensity incident on the interface that is reflected, so:

[0095]

[0096] Similarly, at the internal boundary x = L, the radiation intensity propagating in the negative direction also includes the part of the radiation intensity reflected from the interface, that is:

[0097]

[0098] Combining the radiation transfer equations in the positive and negative directions of the medium and the two boundary conditions, we can simplify it to:

[0099]

[0100] in,

[0101]

[0102] Then the apparent spectral radiation intensity at any angle on the output interface is:

[0103]

[0104] The apparent normal spectral emissivity is:

[0105]

[0106] Where, L T,b is the intensity of blackbody radiation corresponding to temperature T and wavelength λ;

[0107] Apparent spectral transmittance From Bell's law we can get:

[0108]

[0109] Since the isotropic medium temperature Refractive index Absorption coefficient Reflectivity is an assumed value, so the corresponding apparent normal spectral emissivity is Apparent spectral transmittance This is the estimated value of the apparent spectral emissivity Apparent spectral transmittance estimate

[0110] In the present invention, by measuring the thermal radiation transmission characteristics of an infrared hood material of a certain thickness, the corresponding radiation characteristics of the infrared hood material of unit thickness are calculated, and then the thermal radiation characteristic data such as the transmittance of other infrared hood materials of different thicknesses under the same temperature conditions are calculated, thereby realizing the establishment of a quantitative transmission model of the infrared hood.

[0111] The present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A high-efficiency measurement method for the thermal radiation characteristics of high-temperature infrared hood materials of different thicknesses, characterized by: The following steps are involved: Step 1: Build an efficient measurement system for the thermal radiation characteristics of high-temperature infrared hood materials of different thicknesses; the system includes a Fourier transform infrared spectrometer, a heating furnace, a blackbody furnace, a temperature control inspection instrument, and a data acquisition and processing system; during measurement, the center of the Fourier transform infrared spectrometer's detection lens, the center of the heating furnace, and the center of the blackbody furnace cavity are set on the same horizontal line; Step 2: In the initial stage, do not start the heating furnace, do not place any samples in the heating furnace, start the blackbody furnace, and set the blackbody furnace temperature to T b , use Fourier infrared spectrometer to obtain the infrared radiation L of the black body obj ; Step 3: Place the infrared hood sample in a high-temperature heating furnace and heat it until the temperature of the infrared hood sample material reaches the specified temperature T win After the distribution is uniform, the infrared radiation L transmitted through the infrared hood sample material is obtained using an infrared detector. tot ; Step 4: Control the temperature of the sample material to keep it at T win unchanged, change the blackbody temperature T b In this state, repeat steps 2 and 3 to obtain multiple sets of blackbody temperatures T b,i Infrared radiation L in the state obj,i and L tot,i ; where the subscript i represents the i-th measurement; Step 5: When the temperature of the material remains unchanged, its radiation characteristic parameters are fixed values. By statistically analyzing the test results, the least squares method is used to fit multiple sets of blackbody temperatures T b,i Infrared radiation L in the state obj,i and L tot,i , and then the temperature T win Transmittance τ of uniformly distributed infrared hood sample material T,win and self-radiation L T,win ; Step 6: Divide the infrared hood sample into n equal layers along the thickness direction, and obtain the apparent spectral transmittance of the infrared hood sample material per unit thickness Δ according to the energy conservation relationship. Self-radiation Based on Obtain the apparent normal spectral emissivity Step 7: According to the inverse radiation transfer problem solving algorithm, assuming that the refractive index of the infrared hood sample material is The absorption coefficient is The apparent spectral radiation intensity at any angle on the exit interface of the infrared hood sample material is calculated by solving the radiation transfer equation. Apparent normal spectral emissivity estimate and the apparent spectral transmittance estimate Step 8: The apparent normal spectral emissivity of the infrared hood sample material obtained in step 6 and apparent spectral transmittance And the estimated value of the apparent normal emissivity of the infrared hood sample material obtained in step 7 Apparent spectral transmittance estimate Substitute the following objective function calculation formula to calculate the objective function value F obj ; Step 9: Determine the objective function value F in step 8 obj Is it less than the set threshold ξ? If so, the refractive index of the infrared hood sample material assumed in step 8 is Absorption coefficient That is, the real refractive index and absorption coefficient of the infrared hood sample material; If not, return to step 7 and update the refractive index of the infrared hood sample material according to the inverse problem algorithm. Absorption coefficient Reset the refractive index and absorption coefficient of the infrared hood sample material and recalculate until the objective function value F in step eight is obj is less than the set threshold ξ, and the true refractive index of the infrared hood sample material is obtained. Absorption coefficient Combined with step 6, the temperature is now T win The self-radiation of the sample material Refractive index Absorption coefficient Step 10: Change the temperature T of the sample material win Repeat steps 2 to 9 to obtain different temperatures T win,j Under the condition of unit thickness Δ, the refractive index of the infrared hood sample material is Absorption coefficient With its own radiation Where the subscript j indicates the jth group of measurements; The self-radiation of the infrared hood sample material in different directions per unit thickness Δ is obtained by calculation Through different temperatures T win,j The refractive index of the sample material under Absorption coefficient With its own radiation Establish a database of radiation properties of infrared hood materials with unit thickness Δ at different temperatures; Step 11: Using the idea of ​​physical discreteness, divide the infrared hood to be tested into m layers of thin layers with a thickness of Δ; use an infrared thermal imager to measure the temperature of each thin layer of the infrared hood under the working condition to be tested, and record it as T win,k , where the subscript k = 1, 2, …, m, represents the kth thin layer; the temperature field of the infrared hood is established based on the measurement results, and the radiation physical property database of the infrared hood materials with different temperature unit thickness Δ established in step 10 is queried to obtain the refractive index, absorption coefficient, self-radiation distribution field and radiation distribution field in different directions of each infrared hood thin layer; then the refractive index and absorption coefficient at different positions in the infrared hood are obtained, and the directional radiation intensity and directional emissivity of the infrared hood to be measured are obtained by superposition along the thickness direction.

2. The method for efficiently measuring the thermal radiation characteristics of high-temperature infrared hood materials of different thicknesses according to claim 1 is characterized in that: The step 6 obtains the apparent spectral transmittance of the infrared hood sample material per unit thickness Δ Self-radiation The process includes the following steps: The radiation transfer equation is used to describe the transfer process of target radiation energy through the infrared hood specimen. Energy is conserved along the radiation transfer direction. The infrared hood material is divided into n layers. It is assumed that the temperature T of the infrared optical window is uniformly distributed and the apparent spectral transmittance of each layer is and self-radiation Isotropic, according to the radiation transfer principle and energy conservation relationship, the total radiation passing through the first layer of infrared hood material is The infrared radiation passing through the 1st and 2nd layers is Similarly, the total radiation passing through the 1st to nth layers, that is, the total radiation passing through the entire infrared hood, is Then, the apparent spectral transmittance of the infrared hood material with a thickness of Δ and a temperature of T is deduced by the energy method. and the transmittance τ of the infrared detection infrared hood T,win The algebraic relationship between the apparent spectral transmittance and Infrared detection infrared hood transmittance τ T,win algebraic relationship between itself and radiation; By measuring the transmittance and infrared radiation characteristics of an infrared hood with a thickness of x, the apparent spectral transmittance and self-radiative thermal radiation characteristic data of the infrared optical window material with a unit thickness of Δ are obtained; the infrared optical window material is the infrared hood material.

3. The method for efficiently measuring the thermal radiation characteristics of high-temperature infrared hood materials of different thicknesses according to claim 2 is characterized in that: The apparent spectral transmittance of the infrared head cover material and the transmittance τ of the infrared detection infrared hood T,win The algebraic relationship is 4. The method for efficiently measuring the thermal radiation characteristics of high-temperature infrared hood materials of different thicknesses according to claim 3 is characterized in that: The apparent spectral transmittance Infrared detection infrared hood transmittance τ T,win The algebraic relationship between it and its own radiation is 5. A high-efficiency measurement method for thermal radiation characteristics of high-temperature infrared hood materials of different thicknesses according to claim 2, 3 or 4, characterized in that: The apparent normal spectral emissivity obtained in step 6 as follows: Where, L T,b Indicates that the temperature is the same as the temperature of the sample material per unit thickness, that is, the temperature is T win The intensity of blackbody radiation.

6. The method for efficiently measuring the thermal radiation characteristics of high-temperature infrared hood materials of different thicknesses according to claim 5 is characterized in that: Step 7: By solving the radiation transfer equation, the apparent spectral radiation intensity at any angle on the exit interface of the infrared head cover sample material is calculated. Apparent normal spectral emissivity estimate The process includes the following steps: Assume that the temperature of the isotropic medium is Refractive index The absorption coefficient is Reflectivity The thickness of the medium is Δ; under one-dimensional conditions, when the medium is in a steady state and medium scattering is not considered, the radiation transfer equation is simplified to: Solving the simplified radiative transfer equation yields the forward radiation and back radiation θ is the angle between the forward radiation and the backward radiation and the surface normal respectively; At the internal boundary x = 0, the radiation intensity propagating in the positive direction includes the part of the radiation intensity incident on the interface that is reflected, so: Similarly, at the internal boundary x = L, the radiation intensity propagating in the negative direction also includes the part of the radiation intensity reflected from the interface, that is: Combining the radiation transfer equations in the positive and negative directions of the medium and the two boundary conditions, we can simplify it to: in, Then the apparent spectral radiation intensity at any angle on the output interface is: The apparent normal spectral emissivity is: Where, L T,b is the intensity of blackbody radiation corresponding to temperature T and wavelength λ; Since the isotropic medium temperature Refractive index Absorption coefficient Reflectivity is an assumed value, so the corresponding apparent normal spectral emissivity is This is the estimated value of the apparent spectral emissivity 7. The method for efficiently measuring the thermal radiation characteristics of high-temperature infrared hood materials of different thicknesses according to claim 6 is characterized in that: Forward radiation obtained by solving the simplified radiative transfer equation and back radiation as follows:

8. The method for efficiently measuring the thermal radiation characteristics of high-temperature infrared headgear with different thicknesses according to claim 6 is characterized in that: Apparent spectral transmittance estimate from step 7 Calculated using Bell's law.

9. The method for efficiently measuring the thermal radiation characteristics of high-temperature infrared headgear with different thicknesses according to claim 8 is characterized in that: The apparent spectral transmittance estimate is obtained in step 7 The specific process includes the following steps: Apparent spectral transmittance From Bell's law we can get: Since the isotropic medium temperature Refractive index Absorption coefficient Reflectivity is an assumed value, so the corresponding apparent spectral transmittance is Apparent spectral transmittance estimate

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