Determination of UV radiance of NO molecules in non-uniform layers based on line of sight integration method

Abstract

The present invention belongs to the technical field of ultraviolet detection of hypersonic shock layers, and discloses a method for determining ultraviolet radiance of NO molecules in non-uniform stratification based on line of sight integration method, using simulation software to simulate the distribution of corresponding parameters of the gas flow field of a high-speed aircraft flying at high altitude; importing the gradient calculation formula into the flow field to obtain the corresponding gradient distribution cloud map in the flow field; extracting the gradient curves of various parameters on the stagnation line of the shock layer of the hypersonic aircraft, and performing weighted stratification according to the gradient change; stratifying the stagnation line according to the non-uniform stratification of the adaptive grid, exponentially encrypting it near the wall, and extracting various parameters on the adaptive grid nodes; programming the line of sight integral equation of non-uniform stratification, and extracting the flow field parameters required by the program: using the program of the non-uniform stratification line of sight integration method, the ultraviolet radiance of NO molecules in the shock layer is calculated. The present invention greatly improves the accuracy of related calculations.

Description

Technical Field

[0001] The invention belongs to the technical field of ultraviolet detection of hypersonic shock layers, and in particular relates to a method for determining ultraviolet radiance of non-uniformly layered NO molecules based on a line-of-sight integration method. Background Art

[0002] At present, the air in the flow field around a hypersonic vehicle is in a state of vibration excitation, dissociation and ionization. The study of non-equilibrium phenomena and mechanisms in hypersonic flow is an extremely challenging task. When the airflow bypasses an object in a hypersonic flow, a shock wave is inevitably formed near the object. Under the high temperature conditions of the shock layer, the N 2 and O 2 NO molecules, which are easily generated by chemical reactions, are an important radiation source for ultraviolet detection of hypersonic shock layers.

[0003] For situations where there is no scattering or where the scattering problem is not considered, the apparent ray method can be used to efficiently and accurately calculate the radiation transmission characteristics of gas molecules. The apparent ray method simplifies the transmission of light in the non-uniform flow field. The ray intersects with the flow field along the detection direction, and the intersecting part is divided into n layers along the ray direction. For a single-layer medium, which is set as an isothermal and uniform medium, the final radiation intensity value can be calculated by integrating layer by layer along the line of sight. In the actual flow field, the medium will change differently in different distance intervals along the line of sight. Therefore, it is inaccurate to regard each section of the change as uniform, especially in the shock wave layer. The various parameters also change dramatically in a small path, and the changes need to be processed. For areas with fast changes, the layered encryption ensures the accuracy of the calculation. The layered intervals in areas with slow changes can be appropriately enlarged to improve the calculation accuracy and efficiency.

[0004] At present, the grids considered in radiation calculations are mostly virtual grids, no grids, data point amplification and other methods. The non-uniform grids of the flow field are not combined with the radiation calculation during the calculation. The grid discussed in the present invention is an adaptive grid generated according to the flow field characteristics. The calculated grid has strong applicability and does not require the uniformity and high-precision refinement characteristics of the grid. While ensuring the accuracy of the flow field simulation iteration, the flow field data is combined with the layering of the line of sight integration method to accurately extract the required flow field parameters on the non-uniform path, reduce the error in the data amplification process, and improve the calculation efficiency and accuracy.

[0005] Through the above analysis, the problems and defects of the prior art are as follows: the ultraviolet radiance method of non-uniformly layered NO molecules in the prior art has low accuracy and cannot accurately give the calculation results of the NO spectral radiance on the stagnation line of the shock layer of the BSUV aircraft. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a method for determining the ultraviolet radiance of non-uniformly layered NO molecules based on a line of sight integration method.

[0007] The present invention is implemented as follows: a method for determining the ultraviolet radiance of non-uniformly layered NO molecules based on a line of sight integration method, the method for determining the ultraviolet radiance of non-uniformly layered NO molecules based on a line of sight integration method comprising:

[0008] Step 1: Use simulation software to simulate the distribution of temperature, pressure and concentration of each component in the gas flow field of a high-speed aircraft flying at high altitude; obtain the distribution of the shock layer flow field of the hypersonic aircraft, which provides a basis for the gradient calculation in step 2;

[0009] Step 2: The gradient calculation formula is introduced into the flow field to obtain the gradient distribution cloud map of temperature, pressure and NO molecule mole fraction in the flow field; the gradient distribution of temperature, pressure and NO molecule mole fraction in the flow field is obtained, which provides a basis for the extraction of stagnation line gradient in step 3;

[0010] Step 3: extract the temperature gradient, pressure gradient and NO molecular mole fraction gradient curve on the stagnation line of the hypersonic aircraft shock layer, and perform weighted stratification according to the gradient change; obtain the gradient distribution and non-uniform stratification criteria on the stagnation line, providing an accurate input source for step 5;

[0011] Step 4: The stagnation point line is non-uniformly layered according to the adaptive grid, and the exponential density is increased near the wall to extract the temperature, pressure and NO mole fraction on the adaptive grid nodes; the flow field parameters of each node according to the non-uniform layering of the adaptive grid are obtained, providing an accurate input source for step 5;

[0012] Step 5: Program the non-uniform stratified line of sight integral equation and extract the flow field parameters required by the program: Use the non-uniform stratified line of sight integral method to calculate the ultraviolet radiance of NO molecules in the shock layer. The accurate ultraviolet radiation of the stagnation point line of the shock layer is obtained, providing a theoretical basis for ultraviolet detection of hypersonic target shock waves.

[0013] Furthermore, in step 1, the specific process of using simulation software to simulate the distribution of temperature, pressure and concentration of each component of the gas flow field of a high-speed aircraft flying at high altitude is as follows:

[0014] The BSUV hypersonic vehicle model was modeled and simulated using computational fluid dynamics methods. First, the ICEM software was used to perform geometric modeling and structured meshing on the vehicle. The built model was imported into CFD-FASTRAN software and simulated using a dual-temperature and seven-component thermochemical non-equilibrium model of air. The temperature field, pressure field, and NO mole fraction field cloud maps of the shock layer of the BSUV aircraft were obtained.

[0015] Furthermore, in step 2, the gradient calculation formula is introduced into the flow field to obtain the gradient distribution cloud map of temperature, pressure and NO molecule mole fraction in the flow field. The specific process is:

[0016] Import the simulation results into the Tecplot post-processing software and solve the gradient formula By incorporating it into the flow field cloud map, a gradient distribution cloud map of temperature, pressure and NO molecule mole fraction in the shock layer of the BSUV aircraft was obtained.

[0017] Furthermore, in step 3, the temperature gradient, pressure gradient and NO molecule mole fraction gradient curve on the stagnation point line of the hypersonic aircraft shock layer are extracted, and weighted stratification is performed according to the gradient changes. The specific process is as follows:

[0018] The temperature, pressure and NO mole fraction on the stagnation line of the shock layer are extracted, and the layers are weighted according to the gradient change rate. More accurate layer calculations are obtained in places where the gradient changes dramatically while keeping the total number of layers unchanged, and the distance of each non-uniform layer is determined.

[0019] Furthermore, in step 4, the stagnation point line is non-uniformly layered according to the adaptive grid, and the stagnation point line is exponentially encrypted near the wall surface. The specific process of extracting the temperature, pressure and NO mole fraction on the adaptive grid node is as follows:

[0020] Adaptive grid division is performed according to the flow field results. The shock layer position close to the wall is exponentially encrypted. The stagnation point lines are non-uniformly layered according to the adaptive grid. The distance between each segment of the adaptive non-uniform grid in the flow field and the temperature, pressure and NO mole fraction parameter values ​​on the grid nodes are extracted.

[0021] Furthermore, in step 5, the non-uniformly layered line of sight integral equation is programmed, and the flow field parameters required by the program are extracted. The specific process is as follows:

[0022] Import the calculation of flow field parameters on uniform stratified paths; import the calculation of flow field parameters on non-uniform stratified paths with temperature, pressure and NO mole fraction gradients; import the calculation of flow field parameters on non-uniform stratified paths with adaptive grids.

[0023] Furthermore, the specific process of calculating the flow field parameters on the uniformly layered path is as follows:

[0024] The stagnation line of the BUSV spacecraft is evenly divided into 40 layers. The temperature, pressure and mass fraction of each layer are selected at the dividing point and substituted into the absorption coefficient calculation formula to obtain the absorption coefficient of NO molecules in each layer.

[0025] Furthermore, the specific process of calculating the flow field parameters on the non-uniform stratified path of the introduced temperature, pressure and NO mole fraction gradient is as follows:

[0026] The gradient change rate is the basis for sampling points of non-uniform stratification. The weighted stratification is performed according to the gradient change, and the length of each stratification section is determined. This will enable more accurate stratification calculations in places where the gradient changes drastically while keeping the total number of strata unchanged. The flow field data on the stagnation point line is extracted based on the stratification results, and the extracted temperature, pressure and NO mole fraction are brought into the absorption coefficient calculation formula to obtain the NO molecule absorption coefficient of each layer.

[0027] The specific process of calculating the flow field parameters on the non-uniform layered path of the imported adaptive grid is as follows:

[0028] Adaptive meshing was performed based on the flow field results, and the mesh quality was greater than 0.965. The extracted flow field parameters were substituted into the absorption coefficient calculation formula to obtain the NO molecule absorption coefficient of each layer of the adaptive non-uniform mesh.

[0029] Furthermore, in step 5, the procedure of using the non-uniform layered line of sight integration method to calculate the ultraviolet radiance of NO molecules in the shock layer is as follows:

[0030] The UV radiance of NO molecules in the shock layer is calculated using the program of the non-uniform layered line of sight integration method; for a given gas component, the spectral absorption function κ at the wave number η η It is equal to the sum of the absorption coefficients of the spectral lines that overlap each other at η, expressed as The default reference temperature in the HITRAN database is T ref =296K, the spectral intensity of the spectral line at this default temperature can be expressed as:

[0031]

[0032] The background spectrum, the spectral radiance after attenuation from the 1st layer to the M-1th layer and the transmission from the Mth layer to the end of the line of sight, since the radiation of the Mth layer gas medium itself is not absorbed by other layers, the expansion I n_gas The total spectral radiation brightness of LOS by the line of sight integration method of the M layer can be obtained. Assuming the spectral radiation value received at the end of the line of sight is I, then I is:

[0033]

[0034] The line-of-sight integrated radiance equation is programmed, and the non-uniform stratification distance l, flow field temperature T, pressure P, and NO mole fraction are taken as inputs into the calculation.

[0035] Another object of the present invention is to provide a computer device, characterized in that the computer device includes a memory and a processor, the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the following steps:

[0036] Step 1: Use simulation software to simulate the distribution of temperature, pressure and concentration of each component in the gas flow field of a high-speed aircraft flying at high altitude;

[0037] Step 2: Import the gradient calculation formula into the flow field to obtain the gradient distribution cloud map of temperature, pressure and NO molecule mole fraction in the flow field;

[0038] Step 3, extracting the temperature gradient, pressure gradient and NO molecule mole fraction gradient curve on the stagnation point line of the hypersonic aircraft shock layer, and performing weighted stratification according to the gradient changes;

[0039] Step 4: The stagnation point lines are non-uniformly layered according to the adaptive grid, and the points are exponentially encrypted near the wall, and the temperature, pressure and NO mole fraction on the adaptive grid nodes are extracted;

[0040] Step 5: Program the line-of-sight integral equation of the non-uniform stratification and extract the flow field parameters required by the program: Use the program of the non-uniform stratification line-of-sight integral method to calculate the ultraviolet radiance of NO molecules in the shock layer.

[0041] In combination with the above technical solutions and the technical problems solved, please analyze the advantages and positive effects of the technical solutions to be protected by the present invention from the following aspects:

[0042] First, in view of the technical problems existing in the above-mentioned prior art and the difficulty of solving the problems, the technical solutions to be protected by the present invention and the results and data during the research and development process are closely combined to analyze in detail and deeply how the technical solutions of the present invention solve the technical problems, and some creative technical effects brought about after solving the problems. The specific description is as follows:

[0043] The present invention relates the flow field gradient and the adaptive grid to the radiation transfer equation to obtain the spectral radiance of NO molecules in the non-equilibrium flow, and considers the influence of the changes of shock layer temperature, pressure, NO mole fraction and adaptive grid on the stratification criterion in the line of sight integration method, thereby proposing an improved line of sight integration method for non-uniform stratification, greatly improving the accuracy of related calculations, and more accurately giving the calculation results of the spectral radiance of NO on the stagnation line of the shock layer of the BSUV aircraft.

[0044] The present invention improves the LOS method when calculating the ultraviolet radiance of NO molecules on the stagnation line of the shock layer of a high-speed aircraft, discusses an algorithm for improving the original uniform stratification of LOS into non-uniform stratification based on the complex characteristics of the flow field, takes the temperature gradient, pressure gradient, NO concentration gradient and flow field adaptive grid in the flow field as the basis for non-uniform stratification, calculates the spectral radiance under various stratification conditions, and the results show that when the total number of stratifications is the same, the error of the result of stratification according to the adaptive grid is the smallest compared with the experiment. In particular, when calculating the spectral radiance of the NOγ(0,4) transition state, the relative error of the result of non-uniform stratification according to the temperature gradient is smaller and closer to the experimental value, thereby providing a variety of non-uniform stratification methods for further improving the accuracy of calculating the gas radiance by the line of sight integration method.

[0045] Second, considering the technical solution as a whole or from the perspective of the product, the technical effects and advantages of the technical solution to be protected by the present invention are specifically described as follows: The present invention adopts a non-uniform stratified line of sight integration method when calculating the ultraviolet radiation of the hypersonic shock layer, and uses gradient non-uniform stratification and adaptive grid non-uniform stratification to refine the extraction of flow field parameters, which can accurately capture the short-distance and strongly changing shock layer parameters. The comparison of the calculation results with the experiments effectively shows that the present technical solution improves the accuracy of ultraviolet radiation calculation.

[0046] Third, as auxiliary evidence of the inventiveness of the claims of the present invention, it is also reflected in the following important aspects:

[0047] The technical solution of the present invention fills the technical gap in the industry at home and abroad: the current gas radiation calculation methods at home and abroad, whether virtual grid, no grid, data point amplification or calculation using the LOS method, do not combine the non-uniform grid of the flow field with the radiation calculation. The grid discussed in the present invention is an adaptive grid generated according to the flow field characteristics. The calculated grid has strong applicability and does not require the uniformity and high-precision refinement characteristics of the grid. While ensuring the accuracy of the flow field simulation iteration, the flow field data is combined with the layering of the line of sight integration method to accurately extract the required flow field parameters on the non-uniform path, reduce the error in the data amplification process, and improve the calculation efficiency and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a flow chart of a method for determining ultraviolet radiance of non-uniformly layered NO molecules based on line of sight integration method provided in an embodiment of the present invention.

[0049] Figure 2 It is a schematic diagram of the comparison between the stagnation line temperature curve of the shock layer of a BSUV aircraft provided in an embodiment of the present invention and an experiment.

[0050] Figure 3 It is a temperature field gradient cloud map of the shock layer of a BSUV aircraft provided by an embodiment of the present invention.

[0051] Figure 4 It is a schematic diagram of the non-uniform stratification of the stagnation point lines of the shock layer of a BSUV aircraft provided by an embodiment of the present invention based on an adaptive grid.

[0052] Figure 5 It is a comparison chart of the radiance calculation results of five different stratification methods provided in the embodiment of the present invention and the BSUV test data.

[0053] Figure 6 It is a schematic diagram of error curves of radiance at six characteristic peaks calculated by five different stratification methods provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0055] 1. Explanatory Examples In order to enable those skilled in the art to fully understand how to implement the present invention, this section provides an illustrative example that expands and describes the technical solution of the claims.

[0056] like Figure 1 As shown, the method for determining the ultraviolet radiance of non-uniformly layered NO molecules based on the line of sight integration method provided in an embodiment of the present invention includes:

[0057] S101: Use simulation software to simulate the distribution of temperature, pressure and concentration of each component in the gas flow field of a high-speed aircraft flying at high altitude.

[0058] S102: Importing the gradient calculation formula into the flow field, obtaining a gradient distribution cloud map of temperature, pressure and NO molecule mole fraction in the flow field.

[0059] S103: extracting the temperature gradient, pressure gradient and NO molecule mole fraction gradient curve on the stagnation point line of the hypersonic vehicle shock layer, and performing weighted stratification according to the gradient changes.

[0060] S104: The stagnation point lines are non-uniformly layered according to the adaptive grid, and are exponentially encrypted near the wall surface, and the temperature, pressure and NO mole fraction on the adaptive grid nodes are extracted.

[0061] S105: Programming the line-of-sight integral equation of the non-uniform stratification, and extracting the flow field parameters required by the program: using the program of the non-uniform stratification line-of-sight integral method, calculating the ultraviolet radiance of NO molecules in the shock layer.

[0062] In S101 provided in the embodiment of the present invention, the specific process of using simulation software to simulate the distribution of the temperature, pressure and concentration of each component of the gas flow field of a high-speed aircraft flying at high altitude is as follows:

[0063] The BSUV hypersonic vehicle model was modeled and simulated using the computational fluid dynamics (CFD) method. First, the ICEM software was used to perform geometric modeling and structured meshing on the vehicle. The built model was imported into the CFD-FASTRAN software and simulated using the dual-temperature and seven-component thermochemical non-equilibrium model of air. The temperature field, pressure field and NO mole fraction field cloud maps of the shock layer of the BSUV aircraft were obtained.

[0064] In S102 provided in the embodiment of the present invention, the gradient calculation formula is introduced into the flow field to obtain the gradient distribution cloud map of temperature, pressure and NO molecule mole fraction in the flow field. The specific process is:

[0065] Import the simulation results into the Tecplot post-processing software and solve the gradient formula By incorporating it into the flow field cloud map, a gradient distribution cloud map of temperature, pressure and NO molecule mole fraction in the shock layer of the BSUV aircraft was obtained.

[0066] In S103 provided in the embodiment of the present invention, the temperature gradient, pressure gradient and NO molecule mole fraction gradient curve on the stagnation point line of the hypersonic aircraft shock layer are extracted, and weighted stratification is performed according to the gradient changes. The specific process is as follows:

[0067] The temperature, pressure and NO mole fraction on the stagnation line of the shock layer are extracted, and the layers are weighted according to the gradient change rate. More accurate layer calculations are obtained in places where the gradient changes dramatically while keeping the total number of layers unchanged, and the distance of each non-uniform layer is determined.

[0068] In S104 provided in the embodiment of the present invention, the stagnation point line is non-uniformly layered according to the adaptive grid, and is exponentially encrypted near the wall surface. The specific process of extracting the temperature, pressure and NO mole fraction on the adaptive grid node is as follows:

[0069] Adaptive grid division is performed according to the flow field results. The shock layer position close to the wall is exponentially encrypted. The stagnation point lines are non-uniformly layered according to the adaptive grid. The distance between each segment of the adaptive non-uniform grid in the flow field and the temperature, pressure and NO mole fraction parameter values ​​on the grid nodes are extracted.

[0070] In S105 provided in the embodiment of the present invention, the non-uniformly layered line of sight integral equation is programmed, and the flow field parameters required by the program are extracted. The specific process is:

[0071] Import the calculation of flow field parameters on uniform stratified paths; import the calculation of flow field parameters on non-uniform stratified paths with temperature, pressure and NO mole fraction gradients; import the calculation of flow field parameters on non-uniform stratified paths with adaptive grids.

[0072] The specific process of calculating the flow field parameters on the uniformly layered path is as follows:

[0073] The stagnation line of the BUSV spacecraft is evenly divided into 40 layers. The temperature, pressure and mass fraction of each layer are selected at the dividing point and substituted into the absorption coefficient calculation formula to obtain the absorption coefficient of NO molecules in each layer.

[0074] The specific process of calculating the flow field parameters on the non-uniform stratified path of the introduced temperature, pressure and NO mole fraction gradient is as follows:

[0075] The gradient change rate is the basis for sampling points of non-uniform stratification. The stratification is weighted according to the gradient change, and the length of each stratification section is determined. This will enable more accurate stratification calculations in places where the gradient changes drastically while keeping the total number of strata unchanged. The flow field data on the stagnation line is extracted based on the stratification results, and the extracted temperature, pressure and NO mole fraction are substituted into the absorption coefficient calculation formula to obtain the NO molecule absorption coefficient of each layer.

[0076] The specific process of calculating the flow field parameters on the non-uniform layered path of the imported adaptive grid is as follows:

[0077] Adaptive meshing was performed based on the flow field results, and the mesh quality was greater than 0.965. The extracted flow field parameters were substituted into the absorption coefficient calculation formula to obtain the NO molecule absorption coefficient of each layer of the adaptive non-uniform mesh.

[0078] In S105 provided in the embodiment of the present invention, the specific process of calculating the ultraviolet radiance of NO molecules in the shock layer using the program of the non-uniform layered line of sight integration method is as follows:

[0079] The UV radiance of NO molecules in the shock layer is calculated using the program of the non-uniform layered line of sight integration method; for a given gas component, the spectral absorption function κ at the wave number η η It is equal to the sum of the absorption coefficients of the spectral lines that overlap each other at η, expressed as The default reference temperature in the HITRAN database is T ref =296K, the spectral intensity of the spectral line at this default temperature can be expressed as:

[0080]

[0081] The background spectrum, the spectral radiance after attenuation from the 1st layer to the M-1th layer and the transmission from the Mth layer to the end of the line of sight, since the radiation of the Mth layer gas medium itself is not absorbed by other layers, the expansion I n_gasThe total spectral radiation brightness of the LOS of the M-layer line of sight integration method can be obtained. Assuming the spectral radiation value received at the end of the line of sight is I, then I is:

[0082]

[0083] The line-of-sight integrated radiance equation is programmed, and the non-uniform stratification distance l, flow field temperature T, pressure P, and NO mole fraction are taken as inputs into the calculation.

[0084] 2. Application Examples: In order to prove the creativity and technical value of the technical solution of the present invention, this section provides application examples of the technical solution of the claims on specific products or related technologies.

[0085] 1) Simulation software and basic parameters used in the example

[0086] The simulation software used is CFD-FASTRAN, and ICEM is adopted for modeling and meshing.

[0087] Basic parameters of model flight:

[0088] Flight altitude: 38km, flight speed: 3500m / s, ambient air pressure: 51.5Pa, ambient air temperature: 264.9K.

[0089] 2) Specific implementation process

[0090] ICEM is used to build the aircraft model, and the near-wall grid is encrypted according to the shock layer flow field characteristics to obtain an adaptive grid. The model and grid are imported into the simulation software for simulation. The flow field parameters are set as described in (1). The simulated flow field cloud map is imported into Tecplot to calculate the flow field temperature, pressure and NO molecular mole fraction gradient distribution, and the gradient curve on the shock layer stagnation point line is extracted. Non-uniform stratification is performed according to the weighted gradient distribution results. At the same time, stratification is performed according to the non-uniform nodes of the adaptive grid. The non-uniform stratification distance and flow field parameters are brought into the non-uniform line of sight integral equation for calculation.

[0091] 3) Data results

[0092] The error analysis based on the comparison with the experimental peak value shows that when the total number of layers is the same, the weighted total error of the adaptive grid layering is the smallest and closest to the experiment, but when calculating the spectral radiance of the NOγ(0,4) transition state, the relative error of the temperature gradient layering is smaller and closer to the experimental value. The results show that when the number of selected points is the same, the line of sight integration method with non-uniform layering according to the adaptive grid can be optimally selected to obtain the most accurate numerical solution.

[0093] 3. Evidence of the effects of the embodiments. The embodiments of the present invention have achieved some positive effects during the development or use process, and indeed have great advantages over the prior art. The following content is described in conjunction with the data, charts, etc. of the test process.

[0094] 1. Simulation software and basic parameters used in the examples

[0095] The simulation software used is CFD-FASTRAN software, and ICEM modeling and grid generation are adopted. ICEM software is used to perform geometric modeling and structured grid generation on the aircraft. The built model is imported into CFD-FASTRAN software and simulated using dual temperature and seven-component thermochemical non-equilibrium model of air to obtain the temperature field, pressure field and NO mole fraction field cloud map of the shock layer of the BSUV aircraft. The flow field and grid are imported into tecplot software to perform layered processing on the flow field, extract the flow field parameters on the stagnation point line of the shock layer, and derive the parameter gradient. According to the gradient change rate and adaptive grid as the basis for non-uniform layering, the data after layering is imported into the non-uniform line of sight transmission equation for calculation. Taking the shock layer of the BUSV hypersonic aircraft as an example, the basic parameters of the model flight are: blunt body radius: 0.1016m, aircraft bottom height: 0.23m, semi-cone angle: 5°, flight altitude: 38km, flight speed: 3500m / s, surrounding air pressure: 51.5Pa, and surrounding air temperature: 264.9K.

[0096] 2. Data results

[0097] Figure 2 In order to extract the stagnation line temperature of the shock layer simulated by the BSUV model and compare it with the test data, the stagnation line temperature of the two flight tests at flight altitudes of 53.5KM and 71KM was selected for comparison, and the correctness of the simulation results was further demonstrated by comparing with the test temperature curve. Table 1 is a comparison table of the radiance results calculated by five stratification methods, namely uniform stratification and temperature gradient, pressure gradient, NO mole fraction gradient, and adaptive grid non-uniform stratification, with the BSUV test data, as follows:

[0098] Table 1 Radiance results calculated by five stratification methods and BSUV test data

[0099]

[0100] The peak positions of the six groups of NOγ-state transition peaks in the above-mentioned radiance results are in good agreement with the experiment. The result with the smallest error is the adaptive grid layered calculation result, and the result with the largest error is the result calculated according to the NO mole fraction layered calculation result. Among them, the result with the smallest error in the γ(0,4) state peak is the result calculated according to the temperature gradient layered calculation result. It can be seen that in the case of high accuracy requirements in the fine flow field, the radiance result calculated using the adaptive grid non-uniform layered method is the most accurate.

[0101] In summary, the present invention provides a more accurate method for calculating gas radiance, which is of great significance to the research on target warning, detection and identification. The stratification method when calculating the gas radiation transfer equation by the line of sight integral method is improved and analyzed, and the line of sight integral radiance under the non-uniform stratification of flow field temperature, pressure, NO concentration gradient and the non-uniform stratification of flow field adaptive grid is calculated, so that the calculation results of the ultraviolet radiance on the stagnation line of the shock layer are more accurate. At the same time, the non-uniform stratification distance and flow field parameters are used as separate input sources in the process of programming calculation. The use of programming to calculate the ultraviolet spectral radiance of NO molecules on the stagnation line of the shock layer has the significant advantages of high calculation efficiency and accurate calculation results.

[0102] It should be noted that the embodiments of the present invention can be implemented by hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated design hardware. It can be understood by a person of ordinary skill in the art that the above-mentioned devices and methods can be implemented using computer executable instructions and / or contained in a processor control code, such as a carrier medium such as a disk, CD or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. Such code is provided on the carrier medium. The device and its modules of the present invention can be implemented by hardware circuits such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc., can also be implemented by software executed by various types of processors, and can also be implemented by a combination of the above-mentioned hardware circuits and software, such as firmware.

[0103] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for determining the ultraviolet radiance of non-uniformly layered NO molecules based on line of sight integration method, characterized in that: The method for determining the ultraviolet radiance of non-uniformly layered NO molecules based on the line of sight integration method comprises: Step 1: Use simulation software to simulate the distribution of temperature, pressure and concentration of each component in the gas flow field of a high-speed aircraft flying at high altitude; Step 2: Import the gradient calculation formula into the flow field to obtain the gradient distribution cloud map of temperature, pressure and NO molecule mole fraction in the flow field; Step 3, extracting the temperature gradient, pressure gradient and NO molecule mole fraction gradient curve on the stagnation point line of the hypersonic aircraft shock layer, and performing weighted stratification according to the gradient changes; Step 4: The stagnation point lines are non-uniformly layered according to the adaptive grid, and the points are exponentially encrypted near the wall, and the temperature, pressure and NO mole fraction on the adaptive grid nodes are extracted; Step 5, program the line-of-sight integral equation of the non-uniform stratification and extract the flow field parameters required by the program: use the program of the non-uniform stratification line-of-sight integral method to calculate the ultraviolet radiance of NO molecules in the shock layer; In the step 3, the temperature gradient, pressure gradient and NO molecule mole fraction gradient curve on the stagnation point line of the hypersonic aircraft shock layer are extracted, and weighted stratification is performed according to the gradient changes. The specific process is as follows: The temperature, pressure and NO mole fraction on the stagnation point line of the shock layer are extracted, and the layers are weighted according to the gradient change rate. When the total number of layers remains unchanged, more accurate layer calculations are obtained in places where the gradient changes sharply, and the distance of each non-uniform layer is determined; In step 5, the non-uniformly layered line of sight integral equation is programmed, and the flow field parameters required by the program are extracted. The specific process is: Import the calculation of flow field parameters on uniform stratified paths; Import the calculation of flow field parameters on non-uniform stratified paths with temperature, pressure and NO mole fraction gradients; Import the calculation of flow field parameters on non-uniform stratified paths with adaptive grids; The specific process of calculating the flow field parameters on the non-uniform stratified path of the introduced temperature, pressure and NO mole fraction gradient is as follows: The gradient change rate is the basis for sampling points of non-uniform stratification. The weighted stratification is performed according to the gradient change, and the length of each stratification section is determined. This will enable more accurate stratification calculations in places where the gradient changes drastically while keeping the total number of strata unchanged. The flow field data on the stagnation point line is extracted based on the stratification results, and the extracted temperature, pressure and NO mole fraction are brought into the absorption coefficient calculation formula to obtain the NO molecule absorption coefficient of each layer. The specific process of calculating the flow field parameters on the non-uniform layered path of the imported adaptive grid is as follows: Adaptive meshing was performed based on the flow field results, and the mesh quality was greater than 0.

965. The extracted flow field parameters were substituted into the absorption coefficient calculation formula to obtain the NO molecule absorption coefficient of each layer of the adaptive non-uniform mesh.

2. The method for determining the ultraviolet radiance of non-uniformly layered NO molecules based on the line of sight integration method as claimed in claim 1, characterized in that: In the step 1, the specific process of using simulation software to simulate the distribution of temperature, pressure and concentration of each component of the gas flow field of a high-speed aircraft flying at high altitude is as follows: The BSUV hypersonic vehicle model was modeled and simulated using computational fluid dynamics methods. First, the ICEM software was used to perform geometric modeling and structured meshing on the vehicle. The built model was imported into CFD-FASTRAN software and simulated using a dual-temperature and seven-component thermochemical non-equilibrium model of air. The temperature field, pressure field, and NO mole fraction field cloud maps of the shock layer of the BSUV aircraft were obtained.

3. The method for determining the ultraviolet radiance of non-uniformly layered NO molecules based on the line of sight integration method as claimed in claim 1, characterized in that: In step 2, the gradient calculation formula is introduced into the flow field to obtain the gradient distribution cloud map of temperature, pressure and NO molecule mole fraction in the flow field. The specific process is: Import the simulation results into the Tecplot post-processing software and solve the gradient formula By incorporating it into the flow field cloud map, a gradient distribution cloud map of temperature, pressure and NO molecule mole fraction in the shock layer of the BSUV aircraft was obtained.

4. The method for determining the ultraviolet radiance of non-uniformly layered NO molecules based on the line of sight integration method as claimed in claim 1, characterized in that: In step 4, the stagnation line is non-uniformly layered according to the adaptive grid, and the stagnation line is exponentially encrypted near the wall surface. The specific process of extracting the temperature, pressure and NO mole fraction on the adaptive grid node is as follows: Adaptive grid division is performed according to the flow field results. The shock layer position close to the wall is exponentially encrypted. The stagnation point lines are non-uniformly layered according to the adaptive grid. The distance between each segment of the adaptive non-uniform grid in the flow field and the temperature, pressure and NO mole fraction parameter values ​​on the grid nodes are extracted.

5. The method for determining the ultraviolet radiance of non-uniformly layered NO molecules based on the line of sight integration method as claimed in claim 1, characterized in that: The specific process of calculating the flow field parameters on the uniformly layered path is as follows: The stagnation line of the BUSV spacecraft is evenly divided into 40 layers. The temperature, pressure and mass fraction of each layer are selected at the dividing point and substituted into the absorption coefficient calculation formula to obtain the absorption coefficient of NO molecules in each layer.

6. The method for determining the ultraviolet radiance of non-uniformly layered NO molecules based on the line of sight integration method as claimed in claim 1, characterized in that: In step 5, the procedure of the non-uniform layered line of sight integration method is used to calculate the ultraviolet radiance of NO molecules in the shock layer. The specific process is: The UV radiance of NO molecules in the shock layer is calculated using the program of the non-uniform layered line of sight integration method; for a given gas component, the spectral absorption function κ at the wave number η η It is equal to the sum of the absorption coefficients of the spectral lines that overlap each other at η, expressed as The default reference temperature in the HITRAN database is T ref =296K, the spectral intensity of the spectral line at the default reference temperature can be expressed as: The background spectrum, the spectral radiance after attenuation from the 1st layer to the M-1th layer and the transmission from the Mth layer to the end of the line of sight, since the radiation of the Mth layer gas medium itself is not absorbed by other layers, the expansion I n_gas The total spectral radiation brightness of the LOS of the M-layer line of sight integration method can be obtained. Assuming the spectral radiation value received at the end of the line of sight is I, then I is: The line-of-sight integrated radiance equation is programmed, and the non-uniform stratification distance l, flow field temperature T, pressure P, and NO mole fraction are taken as inputs into the calculation.

7. A computer device, characterized in that: The computer device includes a memory and a processor, the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the method for determining the ultraviolet radiance of non-uniformly layered NO molecules based on the line of sight integration method according to any one of claims 1 to 6, including the following steps: Step 1: Use simulation software to simulate the distribution of temperature, pressure and concentration of each component in the gas flow field of a high-speed aircraft flying at high altitude; Step 2: Import the gradient calculation formula into the flow field to obtain the gradient distribution cloud map of temperature, pressure and NO molecule mole fraction in the flow field; Step 3, extracting the temperature gradient, pressure gradient and NO molecule mole fraction gradient curve on the stagnation point line of the hypersonic aircraft shock layer, and performing weighted stratification according to the gradient changes; Step 4: The stagnation point lines are non-uniformly layered according to the adaptive grid, and the points are exponentially encrypted near the wall, and the temperature, pressure and NO mole fraction on the adaptive grid nodes are extracted; Step 5: Program the line-of-sight integral equation of the non-uniform stratification and extract the flow field parameters required by the program: Use the program of the non-uniform stratification line-of-sight integral method to calculate the ultraviolet radiance of NO molecules in the shock layer.

Images