Near-Earth Space Target Infrared Radiation Simulation System and Method

Abstract

The present invention belongs to the field of aerospace technology, and specifically discloses an infrared radiation simulation system and method for near-earth space targets, including: a target geometric modeling and mesh generation module, an orbital heat flux calculation unit module, an infrared radiation calculation unit module, a single-target flight simulation module, and a multi-target flight simulation module, which calculate the solar radiation heat flux density, the earth albedo heat flux density, and the earth radiation heat flux density of the units on the target surface; wherein the earth radiation heat flux density is calculated by the unit hemisphere method; according to the results calculated in S2, the temperature vector of all nodes of the target is calculated by the finite element method; according to the target temperature field, the radiant emittance of the target surface units is calculated; a single-target flight scenario simulation and a multi-target flight scenario simulation are carried out; it has the following advantages: each module can directly connect and transport and input the results within the system without the aid of external software, making the simulation implementation process simple and coherent, and facilitating popularization and application.

Description

Technical Field

[0001] The present invention relates to the field of aerospace technology, and in particular, to an infrared radiation simulation system and method for near-earth space targets. Background Art

[0002] Infrared-guided kinetic energy interceptors and space tracking and surveillance systems pose a serious threat to near-earth space targets. Successful interference with them is the key to improving the survival rate of near-earth space targets. In the process of carrying out research on infrared countermeasure technologies (such as infrared stealth, infrared decoys, etc.), it is necessary to obtain the infrared radiation characteristics of the target and the background. On the one hand, it can guide the research of countermeasure technologies, and on the other hand, it can test the effectiveness of countermeasures. There are three ways to obtain the infrared radiation characteristics of the target and the background: one is physical experiments; the second is theoretical calculations; the third is the combination of theory and practice. Theoretical calculations are quite necessary and important. As long as the calculation model is reasonable and the method is appropriate, theoretical calculation data with reference value can be obtained. How to establish an accurate, simple and complete infrared radiation simulation system for near-earth space targets is the primary problem to be solved. To solve this problem, it is necessary to start from the infrared radiation mechanism of near-earth space targets and obtain a scientific and reasonable physical model of target infrared radiation.

[0003] Theoretical analysis of target infrared radiation first requires calculating the surface temperature of the target. The calculation methods for the temperature field of near-earth space targets mainly use the thermal network method or the lumped parameter method. The lumped parameter method is a very rough algorithm that ignores the thermal resistance of heat conduction inside the object, so its application scenarios are extremely limited. The thermal network method is an algorithm based on the lumped parameter method. It divides the research object into unit nodes, and each node is regarded as a unit with lumped parameters. The heat transfer between nodes is replaced by thermal resistance. Currently, the calculation methods based on the thermal network method have been widely applied in fields such as spacecraft thermal control. However, due to too many physical approximations in the thermal network method and the lack of a strict mathematical basis, the calculation accuracy is not high. The calculation of the target surface temperature field is the basis for calculating the target infrared radiation, and the calculation accuracy of the temperature field directly affects the subsequent infrared radiation characteristic analysis. In view of the importance of the infrared radiation characteristics of near-earth space targets, it is necessary to select a more accurate method.

[0004] With the development of computational heat transfer, a variety of numerical solutions and mature thermal analysis software have emerged, such as ANSYS based on the finite element method (FEM). Therefore, using ANSYS or other calculation methods to analyze the temperature field of near-earth space targets and then using other methods to analyze the target infrared radiation characteristics is complex and cumbersome in the implementation process and is not conducive to popularization and application.

[0005] In the aspect of infrared imaging simulation technology for near-earth space targets, the generation speed of the scene is generally emphasized, while the accuracy of the physical model is ignored. This is because the improvement of the infrared scene generation speed always comes at the cost of sacrificing the calculation accuracy of the target temperature field. For some important near-earth space targets, such as mid-course ballistic targets, accurately analyzing their infrared radiation characteristics is the key, and the speed of infrared imaging is secondary.

[0006] Therefore, an infrared radiation simulation system and method for near-earth space targets are proposed to solve the above-mentioned problems. Summary of the Invention

[0007] The present invention aims to provide an infrared radiation simulation system and method for near-earth space targets to solve or improve at least one of the above technical problems.

[0008] In view of this, the first aspect of the present invention is to provide an infrared radiation simulation system for near-earth space targets.

[0009] The second aspect of the present invention is to provide an infrared radiation simulation method for near-earth space targets.

[0010] The first aspect of the present invention provides an infrared radiation simulation system for near-earth space targets, including: a target geometry modeling and mesh generation module, an orbital heat flux calculation unit module, an infrared radiation calculation unit module, a single-target flight simulation module, and a multi-target flight simulation module;

[0011] The target geometry modeling and mesh generation module is used to set the target type, internal geometric parameters, physical parameters, the number of meridional and zonal emission beams of the internal surface elements of the target, and calculate and output the target mesh node data and the mutual radiation angle coefficient data of the internal surface elements; the orbital heat flux calculation unit module is used to set the solar data, calculation time period, and external heat flux type, read and display the target trajectory and attitude data, and calculate and output the solar radiation heat flux density, earth albedo heat flux density, and earth radiation heat flux density on the target surface; the infrared radiation calculation unit module is used to set the temperature calculation parameters, calculate the target node temperature vector based on the finite element method, output the target finite element node temperature data, and calculate and output the radiant exitance on the target surface; the single-target flight simulation module is used to set the flight simulation speed, display the flight trajectory, attitude, and surface temperature change of the target, and calculate the illuminance of the target on the detector; the multi-target flight simulation module is used to set the flight simulation speed, select the simulation targets and infrared bands, set the observation point position, calculate the target radiation illuminance at the observation point position, and display the various parameters of other targets centered on the first target.

[0012] The infrared radiation simulation system for near-earth space targets provided by the present invention enables all simulation units such as target geometric modeling and mesh generation, orbital heat flux calculation, infrared radiation calculation unit modules, single-target flight simulation modules, and multi-target flight simulation units to be directly connected, transported, and input results within the system without relying on external software. This makes the simulation implementation process simple and coherent, facilitating popularization and application. Moreover, it can complete single-target simulation and multi-target simulation, as well as simulate various situations.

[0013] In addition, the technical solution provided by the embodiment of the present invention may further have the following additional technical features:

[0014] In any of the above technical solutions, displaying the parameters of other targets centered on the first target specifically means: when displaying the temperatures of multiple targets, displaying the temperatures, relative positions, and attitude changes of all targets with the first selected target as the coordinate center; and / or when displaying the radiant illuminance of the target at the observation point, displaying the radiant illuminance of all targets and the relative position changes with the first selected target as the observation center point.

[0015] The second aspect of the present invention provides an infrared radiation simulation method for near-earth space targets, including the following steps: S1, creating a new simulation scenario, setting the type and geometric parameters of the target, and dividing the target into multiple units by meshing; S2, calculating the solar radiation heat flux density, earth albedo heat flux density, and earth radiation heat flux density of the units on the target surface respectively; S3, calculating the temperature vector of all nodes of the target based on the results calculated in S2; S4, calculating the radiant emittance of the units on the target surface based on the node temperature vector of the target; S5, performing a single-target flight scenario simulation, displaying the target flight trajectory, attitude, and surface temperature changes, and calculating the illuminance of the target on the detector based on the results calculated in S2 and the radiant emittance of the units on the target surface; and / or performing a multi-target flight scenario simulation, displaying the illuminance of multiple targets on the detector surface.

[0016] The infrared radiation simulation method for near-earth space targets provided by the present invention calculates the earth radiation heat flux based on the unit hemisphere method. This method is an analytical method that directly calculates the analytical solution of the earth radiation heat flux at the target surface; it uses the finite element method to calculate the target temperature field, which has the advantage of higher calculation accuracy than the thermal network method; calculating temperature is a prerequisite for calculating infrared radiation. By calculating the temperatures of all nodes of the target, the temperature calculation of the target is made more accurate. Therefore, the improvement of temperature calculation accuracy also improves the accuracy of external radiation calculation.

[0017] Specifically, the earth radiation heat flux density is calculated using the unit hemisphere method.

[0018] In any of the above technical solutions, the calculation steps in S2 are specifically as follows: S201, first select a certain unit in the target surface unit, and calculate the solar radiative heat flux density, the earth albedo heat flux density, and the earth radiative heat flux density of this unit respectively; S202, calculate the solar radiative heat flux density, the earth albedo heat flux density, and the earth radiative heat flux density of all units on the target surface in sequence.

[0019] In any of the above technical solutions, let the unit selected in S201 be dA t , and the earth radiative heat flux density of the dA t is calculated by the following formula: Wherein, is the view factor of the earth, and is calculated by the unit hemisphere method, A E represents the earth's surface, σ is the Stefan-Boltzmann constant, T E is the earth temperature, E E is the earth radiative heat flux density on dA t .

[0020] In this technical solution, the earth radiative heat flux is calculated based on the unit hemisphere method. This method is an analytical method, and the analytical solution of the earth radiative heat flux at the target surface is directly calculated, making the earth radiative heat flux density of dA t more accurate during calculation and reducing errors.

[0021] In any of the above technical solutions, the illuminance of the dA t on the detector includes the illuminance of its own radiation on the detector and the illuminance of the reflected ambient radiation on the detector, and the illuminance of its own radiation on the detector is calculated by the following formula:

[0022]

[0023] Wherein, is the illuminance of its own radiation on the detector, and λ 1 and λ 2 respectively represent the lower limit and the upper limit of the calculation band, s represents the target's own radiation, represents the radiative heat flux calculated from the average temperature of the dA t node, and is the area of dA t , is the radiant emittance of dA t Taking the target center O t to establish a rectangular coordinate system, O Det is the detector center, the detector is located in the direction, θ Det is the angle between the detector normal and The included angle between them, θ t is the pitch angle of the detector in the target coordinate system, and is the azimuth angle of the detector in the target coordinate system.

[0024] In this technical solution, after calculating the temperatures of all nodes of the target itself and the virtuality, a more accurate dA t radiant emittance can be provided, and the calculation result of the illuminance of the self-radiation on the detector is further improved for dA t itself.

[0025] In any of the above technical solutions, the unit is a four-node tetrahedral structure.

[0026] In this technical solution, the target is uniformly divided into structured grids in the way of longitude and latitude lines to obtain a plurality of hexahedron eight-node structures, and the top and bottom of the target are pentahedron six-node structures. Each node is numbered, the hexahedron or pentahedron is further divided into several four-node tetrahedrons, the node numbers of each tetrahedron are determined, and the tetrahedral triangular surfaces and node numbers on the inner and outer walls are determined.

[0027] In any of the above technical solutions, all node temperature vectors are iteratively calculated using the following formula: ([C] / Δt + [K]θ){T l+1} = ([C] / Δt - [K](1 - θ)){T l} + {P l}(1 - θ) + {P l+1}θ; where the subscript l represents the calculation time, the subscript l + 1 represents the next moment after the calculation time step, {T l} represents all node temperature vectors of the target temperature field at the l-th moment, [C] represents the heat capacity matrix, [K] represents the heat conduction matrix, {P} represents the heat load vector, the heat load vector of the target external surface unit is composed of spontaneous radiation and received radiation, the received radiation includes solar radiation, earth albedo solar radiation and earth radiation, and is obtained by calculating and superimposing the results calculated by S2 through the finite element formula, the heat load vector of the target internal surface unit is calculated according to the radiation matrix method and the mutual radiation angle coefficient of the unit, θ takes the value by the Galerkin method, that is, θ = 2 / 3, and Δt represents the time variation.

[0028] In this technical solution, by calculating all node temperature vectors of the target, the temperature calculation of the target is more accurate, the omission of considering the thermal conduction resistance inside the object is avoided, and the application occasions of the method are expanded.

[0029] In any of the above technical solutions, the following conditions are used to judge whether to stop the iterative calculation: judge whether the number of iterations of the iterative calculation is less than the set value, and / or {T l+1Whether the maximum value among the differences of all nodes in the adjacent number of iterations is greater than the convergence criterion; if so, continue the calculation, if not, stop the calculation and output {T l+1}.

[0030] In this technical solution, by setting the number of iterations and iterative convergence, the accuracy of the final result can be ensured after iterative calculation, and setting the number of iterations can reduce the calculation burden.

[0031] The beneficial effects of the present invention compared with the prior art are as follows:

[0032] Calculating the earth's radiative heat flux based on the unit hemisphere method, which is an analytical method and directly calculates the analytical solution of the earth's radiative heat flux at the target surface;

[0033] Using the finite element method to calculate the target temperature field, which has the advantage of higher calculation accuracy than the heat network method;

[0034] All simulation units such as target geometric modeling and mesh generation, orbital heat flux calculation, infrared radiation calculation unit module, single-target flight simulation module, and multi-target flight simulation unit can directly connect and transfer and input the results within the system without the aid of external software, making the simulation implementation process simple and coherent, which is conducive to popularization and application.

[0035] The additional aspects and advantages of the embodiments according to the present invention will become apparent in the following description part, or be learned through the practice of the embodiments according to the present invention. Brief Description of the Drawings

[0036] The drawings are only for the purpose of showing specific embodiments and are not considered as a limitation of the present invention.

[0037] Figure 1 It is a schematic diagram of the simulation system of the present invention;

[0038] Figure 2 It is a flowchart of the simulation method of the present invention;

[0039] Figure 3 It is a schematic diagram of the coordinate system for calculating the orbital heat flux of the present invention;

[0040] Figure 4 It is a schematic diagram of the coordinate system for calculating solar radiation and earth albedo heat flux of the present invention;

[0041] Figure 5 It is a schematic diagram of the coordinate system for calculating the earth albedo heat flux of the present invention;

[0042] Figure 6 It is a schematic diagram of the coordinate system for calculating the target infrared radiation of the present invention;

[0043] Figure 7 It is a single-target flight simulation diagram of the present invention;

[0044] Figure 8 This is the multi - target flight simulation diagram of the present invention. Detailed implementation manners

[0045] In order to more clearly understand the above - mentioned objects, features, and advantages of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0046] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0047] Please refer to Figure 1 , the first aspect of the present invention provides a near - earth space target infrared radiation simulation system, including: a target geometry modeling and mesh generation module, an orbital heat flux calculation unit module, an infrared radiation calculation unit module, a single - target flight simulation module, and a multi - target flight simulation module;

[0048] The target geometry modeling and mesh generation module is used to select the target type, set the target geometry parameters, physical parameters, and the calculation parameters of the internal mutual radiation angle coefficient of the target, and calculate and output the target mesh node data for finite - element numerical heat analysis and the internal surface element mutual radiation angle coefficient data.

[0049] The orbital heat flux calculation unit module is used to set the celestial body parameters, read and display the target orbit and attitude data, set the calculation time period, and select the external heat flux type, and calculate and output the solar radiation heat flux, the earth radiation heat flux, and the earth albedo heat flux data for heat analysis and infrared radiation characteristic calculation.

[0050] The infrared radiation calculation unit module is used to set the heat analysis parameters including the temperature calculation convergence criterion and the initial temperature of the target, calculate the target temperature field based on the finite - element method, output the target finite - element node temperature data, set the calculation band of the target infrared radiation emittance, and calculate and output the infrared radiation emittance of each unit on the target surface according to the target surface node temperature and the reflected external heat flux data.

[0051] The single - target flight simulation module is used to set the flight simulation speed, display the spatial orientation and flight attitude of the currently selected target in the equatorial inertial coordinate system, and display the temperature change of the target during flight in the target body coordinate system.

[0052] The multi-target flight simulation module is used to set the flight simulation speed, select the simulation targets and infrared bands, set the positions of the observation points, calculate the target irradiance at the positions of the observation points, and when displaying the multi-target temperatures, display the temperatures, relative positions and attitude changes of all targets with the first selected target as the coordinate center, and when displaying the target irradiance at the observation points, display the irradiance and relative position changes of all targets with the first selected target as the observation center point.

[0053] Please refer to Figures 2 - 8 , the second aspect of the present invention provides a method for simulating the infrared radiation of near-earth space targets, including the following steps:

[0054] Step 1: Create a simulation scenario:

[0055] Set the number of targets to be simulated and the current simulation targets, and clear if there is a simulation scenario.

[0056] Step 2: Select the target type and divide the grid:

[0057] 2a. Select the target type, including four types: conical, spherical, cylindrical and warhead-shaped.

[0058] 2b. Set the internal geometric parameters of the target. The geometric parameters of the conical target are the inner cone height, inner bottom radius, spherical cap bottom radius, and spherical cap radius; the geometric parameters of the spherical target are the inner radius; the geometric parameters of the cylindrical target are the inner bottom radius and inner height; the geometric parameters of the warhead-shaped target are the upper cone inner height, lower cone inner height, upper cone inner bottom radius, lower cone inner bottom radius, spherical cap bottom radius, and spherical cap radius.

[0059] 2c. Set the number of target structure layers, the thickness of each layer and the number of subdivisions of each layer.

[0060] 2d. Set the thermal conductivity k, specific heat capacity c and density ρ of the materials of each layer of the target. It is considered that the target is a diffuse gray body, and the emissivities of the inner and outer walls are set.

[0061] 2e. Uniformly divide the target into structured grids in the form of longitude and latitude lines to obtain a series of hexahedron eight-node elements or five-sided six-node elements at the top and bottom of the target. Number each node, further divide the hexahedron or pentahedron into several tetrahedron four-node elements, determine the node numbers of each tetrahedron, and determine the tetrahedron triangular surfaces and node numbers on the inner and outer walls.

[0062] 2f. Establish the target body coordinate system and calculate the node coordinates according to geometric principles.

[0063] 2g. Determine the number of meridional and zonal emission beams of the internal surface elements of the target, and calculate the mutual radiation view factors of the internal surface elements based on the Mont-Carlo method.

[0064] Step 3: Read the target flight trajectory, attitude, and solar data, including the coordinates of the target in the geocentric rectangular coordinate system, roll angle, pitch angle, and yaw angle, as well as the data of the distance between the sun and the target, solar azimuth angle, and solar altitude angle.

[0065] Step 4: Set the parameters of the start time, end time, and calculation time step for the external heat flux calculation.

[0066] Step 5: Calculate the solar radiation heat flux density E on the target surface S :

[0067] 5a. Calculate the solar radiation heat flux density e at the target position S :

[0068]

[0069] where R S represents the solar radius, D ST represents the distance between the sun and the target, T S represents the solar surface temperature, σ is the Stefan - Boltzmann constant, and E S represents the solar radiation heat flux density at the target position;

[0070] 5b. Refer to Figure 3 and Figure 4 to calculate the solar radiation heat flux density E on the target surface element S :

[0071]

[0072] where represents the unit direction vector of sunlight, represents the outward unit normal vector, H represents the distance between the target and the earth's center, R E represents the radius of the earth including the atmospheric system, θ S ′ represents the vector and the included angle between them, O′ represents the geometric center of dA t the center of the earth, π represents pi, and e S represents the solar radiation heat flux density at the target position;

[0073] 5c. Refer to steps 5a and 5b, and similarly calculate the solar radiation heat flux density of all surface elements of the target.

[0074] Step 6: Calculate the earth - albedo heat flux density on the target surface:

[0075] 6a. Refer to Figures 3 - 5 to calculate the target surface element dA tSolar radiation heat flux density E on SE :

[0076] or

[0077]

[0078] where ρ E represents the Earth albedo, e SE represents the solar radiation heat flux density at the Earth's surface, Γ v represents the Earth's spherical cap visible to the near-Earth space target, Γ L represents the area irradiated by the sun, Γ v ∩Γ L represents the area of Earth albedo radiation, dA 1 represents an infinitesimal surface element on the Earth's surface, U represents the geometric center of dA 1 O′ represents the geometric center of dA t ; represents the outward unit normal vector of dA 1 ;

[0079] 6b. Referring to step 6a, calculate the Earth albedo heat flux density of all surface elements of the target in the same way.

[0080] Step Seven: Calculate the Earth heat flux on the target surface:

[0081] 7a. Calculate the view factor of dA t to the Earth using the unit hemisphere method A E represents the Earth's surface;

[0082] 7b. Calculate the Earth radiation heat flux density E t on the target surface element dA E :

[0083]

[0084] where T E represents the Earth temperature, E E represents the Earth radiation heat flux density on the target surface element dA t ; represents the view factor to the Earth;

[0085] 7c. Referring to steps 7a and 7b, calculate the Earth radiation heat flux density of all surface elements of the target in the same way.

[0086] Step Eight: Set the temperature calculation parameters, including the start time, end time, time step (obtained from step four), initial temperature, convergence criterion, maximum number of iterations, internal heat source irradiance, and set the infrared radiation calculation band.

[0087] Step Nine: Calculate the target temperature vector {T l+1}:

[0088] ([C] / Δt + [K]θ){T l+1} = ([C] / Δt - [K](1 - θ)){T l} + {P l}(1 - θ) + {P l+1}θ

[0089] where the subscript l represents the calculation time, the subscript l + 1 represents the next moment after the calculation time step, {T l} represents the temperature vector of all nodes in the target temperature field at time l, [C] represents the heat capacity matrix, [K] represents the heat conduction matrix and the heat load vector, {P} represents the heat load vector composed of spontaneous radiation and received radiation. The received radiation includes solar radiation, earth albedo solar radiation and earth radiation, which is obtained by calculating and superimposing the heat flux density obtained in Steps Five, Six, and Seven through the finite element formula. The internal radiation heat transfer of the target is calculated according to the radiation matrix method and the element mutual radiation angle factor. θ takes the value by the Galerkin method, that is, θ = 2 / 3, and Δt represents the time variation;

[0090] Given {T l}, iteratively solve for the next moment {T l+1}. When the number of iterations or the convergence condition is reached, the calculation ends.

[0091] Step Ten: Calculate the radiant emittance of the target surface:

[0092] 10a. Calculate the radiant emittance of the target surface element

[0093]

[0094] where λ represents the wavelength, λ 1 and λ 2 represent the lower and upper limits of the calculation band respectively, represents the emissivity of dA t , represents the average temperature of the nodes on dA t , which is obtained by taking the arithmetic mean of the temperatures of all nodes on dA l+1 in {T t}. σ represents the Stefan - Boltzmann constant, c 1 and c 2 represent two constants (c 1 = 3.742×10 -16 W·m 2 , c 2 = 1.439×10-2 m·K);

[0095] 10b, calculate the radiant emittance of all cells on the target surface.

[0096] Step Eleven: Single-target flight scenario simulation, display the target flight trajectory, attitude, and surface temperature changes, use the OpenGL graphics library for scene rendering, and obtain the simulation result diagrams of the target flight trajectory, attitude, and surface temperature, such as Figure 7 .

[0097] Step Twelve: Calculate the illuminance of the target on the detector:

[0098] 12a, refer to Figure 6 , calculate the illuminance of the radiation from the target surface cell dA t itself on the detector

[0099]

[0100] Among them, represents the radiant heat flux calculated using the average temperature of the dA t nodes, is the area, the subscript s represents the self-radiation of the target, establish a rectangular coordinate system with the target center O t , O Det is the detector center, the detector is located in the direction, θ Det represents the angle between the detector normal and θ t represents the pitch angle of the detector in the target coordinate system, represents the azimuth angle of the detector in the target coordinate system, represents the illuminance of the radiation from the target surface cell dA t itself on the detector;

[0101] 12b, calculate the illuminance of the reflected ambient radiation from the target surface cell on the detector

[0102] Among them, the subscript r represents the reflected ambient radiation from the target surface, K S and K E are two proportionality coefficients related to the sun and the earth respectively, represents the illuminance of the reflected ambient radiation from the target surface cell on the detector;

[0103]

[0104] Among them, T represents the temperature of the sun or the earth;

[0105] 12c, calculate the illuminance of all surface units of the target on the detector.

[0106] Step Thirteen: Multi-target flight scenario simulation. With the first selected target as the observation center point, display the radiant illuminance and relative position changes of all targets, and use the OpenGL graphics library for scene rendering to obtain the illuminance simulation result diagram of the targets in the 1μm - 3μm band, as Figure 7 .

[0107] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0108] The embodiments described above are only for describing the preferred mode of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. Near-Earth Space Target Infrared Radiation Simulation System, Characterized in that, It includes: Target geometric modeling and mesh generation module, orbital heat flux calculation unit module, infrared radiation calculation unit module, single-target flight simulation module, and multi-target flight simulation module; The target geometric modeling and mesh generation module is used to set the target type, internal geometric parameters, physical parameters, the number of meridional and zonal emission beams of the internal surface elements of the target, calculate and output the target mesh node data and the mutual radiation angle coefficient data of the internal surface elements; The unit has a four-node tetrahedral structure; The orbital heat flux calculation unit module is used to set solar data, calculation time period, and external heat flux type, read and display the target trajectory and attitude data, calculate and output the solar radiation heat flux density, earth albedo heat flux density, and earth radiation heat flux density on the target surface; The infrared radiation calculation unit module is used to set temperature calculation parameters, calculate the target temperature field based on the finite element method, output the target finite element node temperature data, calculate and output the radiant emittance of the target surface; The node temperature data is a node temperature vector, and is iteratively calculated using the following formula: ([C] / Δt + [K]θ){T l+1} = ([C] / Δt - [K](1 - θ)){T l} + {P l}(1 - θ) + {P l+1}θ; Among them, the subscript l represents the calculation moment, the subscript l+1 represents the next moment after the calculation time step, {T l} represents the temperature vector of all nodes of the target temperature field at the l-th moment, [C] represents the heat capacity matrix, [K] represents the heat conduction matrix, {P} represents the heat load vector, and the heat load vector of the target external surface element is composed of spontaneous radiation and received radiation. The received radiation includes solar radiation, earth albedo solar radiation, and earth radiation, and is obtained by superposition through finite element formula calculation of the result calculated by S2. The heat load vector of the target internal surface element is calculated according to the radiation matrix method and the mutual radiation angle coefficient of the element. θ takes a value by the Galerkin method, that is, θ = 2 / 3. Δt represents the time variation; The single-target flight simulation module is used to set the flight simulation speed, display the flight trajectory, attitude, and surface temperature changes of the target, and calculate the illuminance of the target on the detector; The multi-target flight simulation module is used to set the flight simulation speed, select simulation targets and infrared bands, set the observation point position, calculate the target radiation illuminance at the observation point position, and display the various parameters of all targets centered on the first target.

2. The near-Earth space target infrared radiation simulation system according to claim 1, Characterized in that, The display of the various parameters of other targets centered on the first target specifically includes: When displaying the multi-target temperature, display the temperatures, relative positions, and attitude changes of all targets centered on the first selected target; and / or When displaying the target radiation illuminance at the observation point, display the target radiation illuminance and relative position changes of all targets centered on the first selected target as the observation center point.

3. Near-Earth Space Target Infrared Radiation Simulation Method, Characterized in that, It includes the following steps: S1. Create a new simulation scenario, set the type and geometric parameters of the target, and divide the target into meshes to obtain multiple units; S2. Calculate the solar radiation heat flux density, earth albedo heat flux density, and earth radiation heat flux density of the units on the target surface respectively; among them, the earth radiation heat flux density is calculated using the unit hemisphere method; S3. Calculate the temperature vector of all nodes of the target using the finite element method according to the results calculated in S2; S4. Calculate the radiant emittance of the target surface elements according to the node temperature vector of the target; S5. Conduct a single-target flight scenario simulation, display the target flight trajectory, attitude, and surface temperature changes, and calculate the illuminance of the target on the detector according to the results calculated in S2 and the radiant emittance of the target surface elements; S6. Conduct a multi-target flight scenario simulation and display the illuminance of multiple targets on the detector surface; Among them, the method is implemented by the system according to any one of claims 1-2; The unit has a four-node tetrahedral structure; The iterative calculation of all node temperature vectors is carried out using the following formula: ([C] / Δt + [K]θ){T l+1}) = ([C] / Δt - [K](1 - θ)){T l} + {P l}(1 - θ) + {P l+1}θ; where the subscript l represents the calculation moment, the subscript l+1 represents the next moment after the calculation time step, {T l} represents the temperature vector of all nodes of the target temperature field at the l-th moment, [C] represents the heat capacity matrix, [K] represents the heat conduction matrix, {P} represents the heat load vector, the heat load vector of the target external surface element is composed of spontaneous radiation and received radiation, the received radiation includes solar radiation, earth albedo solar radiation and earth radiation, and is obtained by superposition through finite element formula calculation of the result calculated by S2, the heat load vector of the target internal surface element is calculated according to the radiation matrix method and the mutual radiation angle coefficient of the element, θ takes the value by the Galerkin method, that is, θ = 2 / 3, and Δt represents the time variation.

4. The near-earth space target infrared radiation simulation method according to claim 3, characterized in that the calculation steps in S2 are specifically as follows: S201, first select a certain unit in the target surface unit, and calculate the solar radiation heat flux density, the earth albedo heat flux density, and the earth radiation heat flux density of a certain unit respectively; S202, according to the results calculated in S201, calculate the solar radiation heat flux density, the earth albedo heat flux density, and the earth radiation heat flux density of all units on the target surface.

5. The near-earth space target infrared radiation simulation method according to claim 4, characterized in that Set the certain unit to dA t , and the terrestrial radiative heat flux density of the dA t is calculated by the following formula: Among them, is the angular coefficient of the Earth and is calculated using the unit hemisphere method. A E represents the Earth's surface, σ is the Stefan-Boltzmann constant, T E is the Earth's temperature, E E is the heat flux density of the Earth's radiation on dA t ​ 6. The near-earth space target infrared radiation simulation method according to claim 5, characterized in that The dA t The illuminance on the detector includes the illuminance of its own radiation on the detector and the illuminance of the reflected ambient radiation on the detector, and the illuminance of its own radiation on the detector is calculated by the following formula: wherein, is the illuminance of the self-radiation on the detector, and λ 1 and λ 2 respectively represent the lower limit and the upper limit of the calculation band, s represents the self-radiation of the target, represents the radiant heat flux calculated using the average temperature of the dA t nodes, and is the area of dA t ; is the radiant emittance of dA t ; a rectangular coordinate system is established with the target center O t as the origin, O Det is the center of the detector, the detector is located in the direction, θ Det is the angle between the detector normal and ; θ t is the pitch angle of the detector in the target coordinate system, is the azimuth angle of the detector in the target coordinate system.

7. The near-earth space target infrared radiation simulation method according to claim 3, characterized in that the following conditions are used to judge whether to stop the iterative calculation: Determine whether the number of iterations of the iterative calculation is less than a set value, and / or whether the maximum value among the differences of all nodes in {T l+1} for the adjacent number of iterations is greater than the convergence criterion; if so, continue the calculation, if not, stop the calculation and output {T l+1}.

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