Calibration and control method and system for ultra-low orbit satellite simulation aerodynamic heat flow

Abstract

The invention provides a calibration and control method and system for ultra-low orbit satellite simulation aerodynamic heat flow. The method comprises the following steps: constructing an infrared quartz lamp tube array, and arranging a heat flow meter array at the position of a heating surface; constructing a multivariable feedback closed-loop control system, taking the power supply current of each lamp tube in the infrared quartz lamp tube array as an input variable, and taking the measurement value of each heat flow meter in the heat flow meter array as an output variable; based on the multivariable feedback closed-loop control system, executing first heat flow calibration so as to optimize power supply current distribution of each lamp tube; executing second heat flow calibration, and calibrating the heat flow of the non-contact lamp array by using the contact heat source; and executing a system-level vacuum thermal test based on the lamp tube current determined by the second heat flow calibration. According to the calibration and control method provided by the invention, refined and intelligent control on the large-area and high-heat-flux infrared lamp array can be realized, and the uniformity of heat flux loading is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of spacecraft thermal control technology, specifically to a calibration and control method and system for simulating aerodynamic heat flow in ultra-low orbit satellites. Background Technology

[0002] Ultra-low Earth Orbit (ULEO) typically refers to Earth orbit with an altitude between 100 and 350 kilometers. Satellites operating in this orbital region, i.e., ULEO satellites, have significant advantages such as high observation resolution, short communication latency, and low launch costs. Therefore, they are considered a new approach for future space missions such as Earth observation, scientific exploration, and rapid response, and are attracting widespread attention from many countries, gradually becoming a research hotspot in space technology.

[0003] However, as the orbital altitude decreases, the atmospheric density of the satellite's environment gradually increases. When the satellite travels at ultra-high speeds (e.g., 7.8 km / s), it experiences intense friction with the molecules in the thin atmosphere, generating severe aerodynamic heating effects. These effects cause the satellite's surface, especially the windward side, to experience extremely high heat flux density and temperature, posing a serious threat to the satellite's structural safety, material properties, and the normal operation of its internal components. Therefore, accurate prediction and effective protection against aerodynamic heating, as well as ground-based verification tests, have become core technical challenges in the development of ultra-low orbit satellites.

[0004] Table 1 shows the aerodynamic heat flux experienced by the satellite surface at different orbital altitudes. From Table 1, it can be seen that at the same orbital altitude, the aerodynamic heat flux in the frontal windward region is much greater than that in the oblique side windward region, and the aerodynamic heat flux in the oblique side windward region is much greater than that in the non-windward region; as the orbital altitude decreases, the aerodynamic heat flux increases significantly.

[0005] Table 1 Aerodynamic heat flux at different orbital altitudes To simulate and evaluate the thermal environment of ultra-low Earth orbit (ULE) satellites during their in-orbit flight, aerodynamic heat flux simulation loading tests are typically conducted. Currently, the industry commonly uses arrayed infrared quartz lamps as non-contact heating sources to simulate the aerodynamic heat flux experienced by the satellite's outer surface. For example, for a satellite with an orbital altitude of 120 km, the aerodynamic heat flux experienced by its frontal windward region can reach 5100 W / m². Ensuring the accuracy (i.e., the actual loading value matches the theoretical target value) and uniformity (i.e., the heat flux distribution on the heated surface conforms to the theoretical distribution, avoiding localized overheating or undercooling) of this high heat flux loading directly determines the confidence level of the ground test results and the reliability of the satellite's thermal protection design.

[0006] Existing methods for controlling the heat flux of infrared lamp arrays are typically simple, such as total power control or zoned proportional control. These methods do not fully consider the thermal radiation coupling effect between lamps, the complex geometric relationship between lamps and test specimens, and the aging drift of lamp performance over time. When faced with high heat fluxes of 5000 W / m² and complex curved surfaces (such as the top and sides of satellites), traditional methods struggle to simultaneously ensure the accuracy and uniformity of heat flux loading, easily leading to problems such as excessive local heat flux deviations and uneven temperature distribution in the heating area, severely impacting test quality. Summary of the Invention

[0007] The objective of this invention is to provide a calibration and control method and system for simulating aerodynamic heat flux in ultra-low orbit satellites. Through the method and / or system, the problem of insufficient accuracy and uniformity of aerodynamic heat flux loading in ground thermal tests of ultra-low orbit satellites in the prior art is solved. It realizes refined and intelligent control of large-area, high heat flux density infrared lamp arrays, and significantly improves the uniformity of heat flux loading.

[0008] In a first aspect of the invention, the aforementioned task is accomplished by a calibration and control method for simulating aerodynamic heat flow in a very low Earth orbit satellite, the method comprising the following steps: Construct an array of infrared quartz lamps and arrange an array of heat flow meters at the heated surface; A multivariable feedback closed-loop control system is constructed, wherein the power supply current of each lamp in the infrared quartz lamp array is used as the input variable, and the measured value of each heat flow meter in the heat flow meter array is used as the output variable. Based on the multivariable feedback closed-loop control system, the first heat flow calibration is performed to optimize the power supply current distribution of each lamp. Perform a second heat flux calibration, using a contact heat source to calibrate the heat flux of the non-contact lamp array; and Based on the lamp current determined by the second heat flow calibration, a system-level vacuum thermal test is performed.

[0009] In one embodiment of the present invention, the first heat flow calibration includes: The top light array and the side light array were calibrated independently. Target heat flux values ​​are set for each heat flux meter based on simulated aerodynamic heat flux values; and The current of each lamp is dynamically adjusted by a PID control algorithm, and the Jacobian matrix is ​​constructed using calibration test data. The optimal current distribution that minimizes the deviation between the measured values ​​of each heat flow meter and the target heat flow value is solved by linear least squares iterative approximation.

[0010] In one embodiment of the present invention, the second heat flow calibration includes: A calibration plate with compensated heating is provided. The calibration plate has a multi-layer heat insulation component on the back and a ceramic heating element and a temperature sensor attached to the front. The infrared quartz lamp array is turned off, and a known heat flux is applied to the calibration plate via contact heating through the ceramic heating element. The first temperature value at which steady state is reached is recorded. Disconnect the ceramic heating element, start the infrared quartz lamp array, heat the calibration plate in a non-contact manner, adjust the lamp current until the temperature sensor reaches the first temperature value, and record the lamp current at this time as the final calibration result.

[0011] In one embodiment of the present invention, the heat flow meter in the heat flow meter array is an adiabatic heat flow meter, which includes a sensitive element, a thermocouple, a multilayer insulation component, a compensating element, and a base plate; the multilayer insulation component is disposed between the compensating element and the sensitive element to isolate conductive and radiative heat transfer in a vacuum environment.

[0012] In one embodiment of the present invention, the heat balance equation of the adiabatic heat flow meter is established, and the relationship between the surface temperature measured by the thermocouple and the arriving heat flow is determined by the following formula: in, This indicates the heat flow from the lamp to the heat flow meter. This indicates the total absorption rate of the heat flow meter for the radiant energy emitted by the lamp. Represents the Stefan-Boltzmann constant. Indicates the emissivity of the heat flow meter surface. This indicates the surface temperature of the heat flow meter. Indicates multiplication; Among them, total absorption rate The calculation formula is as follows: in, The absorption rate of the black varnish material of the heat flow meter to the energy in the λ spectral band can be obtained by measurement; express Radiant energy in the spectral band This represents the total radiated energy.

[0013] In one embodiment of the present invention, a transfer function from lamp current to heat flux density is established. This transfer function is based on Planck's radiation law and Stefan-Boltzmann's law, and takes into account the lamp array geometry and radiation attenuation, as well as the heat flux density. It can be expressed by the following formula: Where N represents the number of fluorescent tubes. Indicates hemispherical infrared emissivity, Represents the Stefan-Boltzmann constant. This represents the temperature of the i-th lamp. This represents the distance from the i-th lamp to the j-th heat flow meter. Indicates the radiation angle. Indicates the effective radiation area.

[0014] In one embodiment of the present invention, the current of each lamp is dynamically adjusted by a PID control method, and the objective function is defined as the root mean square error of the measured values ​​of each heat flux meter. for, Where M represents the number of heat flow meters, This represents the deviation between the measured value of the j-th heat flow meter and the target value. This indicates the target heat flux value set for each heat flux meter; in, It can be derived from the following formula, in, This represents the measured value of the j-th heat flow meter; The optimal lamp current solution is obtained by minimizing the objective function using the linear least squares iterative method.

[0015] In one embodiment of the present invention, the system-level vacuum thermal test is conducted in a space environment simulation device, wherein the internal pressure of the space environment simulation device is below 10. −3 Pa, the internal temperature of the space environment simulation device is below -173℃, and the inner surface of the space environment simulation device is coated with a black coating with an infrared emissivity higher than 0.88.

[0016] In a second aspect of the invention, the aforementioned task is further addressed by a calibration and control system for simulated aerodynamic heat flow in ultra-low Earth orbit (ULE) satellites. This system is used in the aforementioned calibration and control method for simulated aerodynamic heat flow in ULE satellites, and includes: An infrared quartz lamp array, comprising a top lamp array and a side lamp array, is used to simulate the loading of aerodynamic heat flow onto the test specimen; A heat flow meter array is arranged on the heated surface of the test specimen to monitor the heat flow distribution in real time. A power supply, which is electrically connected to each lamp in the infrared quartz lamp array, is used to independently control the power supply current of each lamp. A data acquisition device, electrically connected to the heat flux meter array, is used to acquire heat flux measurement data; The control unit is communicatively connected to both the power supply and the data acquisition device, and is configured to perform the steps in the calibration and control method for simulated aerodynamic heat flow of the ultra-low orbit satellite.

[0017] In one embodiment of the present invention, the control unit includes a PID controller and an iterative optimization module. The PID controller is used to dynamically adjust the lamp current according to the heat flow deviation, and the iterative optimization module is used to construct the Jacobian matrix and iteratively solve for the optimal current distribution using the linear least squares method.

[0018] The technical solution provided by this invention has the following advantages: 1) The calibration and control method for simulating aerodynamic heat flux of ultra-low orbit satellites proposed in this invention establishes a multivariable feedback closed-loop control system, which links the current of each lamp tube with the measured value of each heat flux meter, and uses PID control and the least squares iterative method based on the Jacobian matrix to solve the problem. This method can achieve refined and intelligent control of large-area, high heat flux density infrared lamp arrays and significantly improve the uniformity of heat flux loading.

[0019] 2) The calibration and control method for simulated aerodynamic heat flux of ultra-low orbit satellites proposed in this invention addresses the issue of uniform heat flux distribution in the lamp array through a first heat flux calibration. The second heat flux calibration uses a contact heating source for comparative calibration, effectively eliminating systematic errors in non-contact heating systems and ensuring the absolute accuracy of heat flux loading. This dual guarantee mechanism of uniformity and accuracy significantly improves the reliability of ground tests.

[0020] 3) The calibration and control method and / or system for simulated aerodynamic heat flow of ultra-low orbit satellites proposed in this invention designs a high-precision adiabatic heat flow meter, which effectively isolates heat exchange on non-target surfaces through multi-layer thermal insulation components. Combined with accurate heat balance equations, it provides accurate and reliable feedback signals for closed-loop control systems, which is the basis for achieving precise control.

[0021] 4) The calibration and control method and / or system for simulating aerodynamic heat flux of ultra-low orbit satellites proposed in this invention are particularly suitable for high heat flux density simulation tests at the level of 5000W / m² and above, solving the key technical problems of ultra-low orbit satellite thermal tests and having important engineering application value. Attached Figure Description

[0022] To further illustrate the above and other advantages and features of the various embodiments of the present invention, a more specific description of the various embodiments of the present invention will be presented with reference to the accompanying drawings. It is to be understood that these drawings depict only typical embodiments of the invention and are therefore not intended to limit its scope. In the drawings, identical or corresponding parts will be indicated by identical or similar reference numerals for clarity.

[0023] Figure 1 A flowchart illustrating the calibration and control method for simulated aerodynamic heat flow of a low-Earth orbit satellite according to an embodiment of the present invention is shown. Figure 2A schematic diagram of a heat-loaded lamp array according to an embodiment of the present invention is shown; Figure 3 A schematic diagram of the structure of an adiabatic heat flow meter according to an embodiment of the present invention is shown; Figure 4 A schematic diagram of a multivariable feedback closed-loop control system according to an embodiment of the present invention is shown; Figure 5 A schematic diagram of the first heat flux calibration according to an embodiment of the present invention is shown; Figure 6 A schematic diagram of the aerodynamic thermal flux calibration test procedure design according to an embodiment of the present invention is shown; and Figure 7 A schematic diagram of a system thermal test according to an embodiment of the present invention is shown. Detailed Implementation

[0024] In the following description, the invention is described with reference to various embodiments. However, those skilled in the art will recognize that the embodiments may be practiced without one or more specific details or with other alternatives and / or additional methods or components. In other instances, well-known structures or operations are not shown or described in detail so as not to obscure the inventive points of the invention. Similarly, for illustrative purposes, specific numbers and configurations are set forth to provide a comprehensive understanding of the embodiments of the invention. However, the invention is not limited to these specific details.

[0025] In this specification, references to "an embodiment" or "this embodiment" mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of the invention. The phrase "in one embodiment" appearing throughout this specification does not necessarily refer to the same embodiment in all instances.

[0026] It should be noted that the embodiments of the present invention describe the method steps in a specific order; however, this is only for illustrating the specific embodiment and not for limiting the order of the steps. On the contrary, in different embodiments of the present invention, the order of the steps can be adjusted according to actual needs.

[0027] In this invention, the various networks, modules, or units of the system according to the invention can be implemented using software, hardware, firmware, or a combination thereof. When a module is implemented using software, its function can be implemented through computer program flow. For example, the module can be implemented using code segments (such as code segments in languages ​​like C and C++) stored in a storage device (such as a hard disk, memory, etc.), wherein the corresponding function of the module can be implemented when the code segment is executed by a processor. When a module is implemented using hardware, its function can be implemented by setting a corresponding hardware structure. For example, the module's function can be implemented by hardware programming a programmable device such as a field-programmable gate array (FPGA), or by designing an application-specific integrated circuit (ASIC) that includes multiple transistors, resistors, capacitors, and other electronic devices. When a module is implemented using firmware, the module's function can be written in the form of program code into a read-only memory such as an EPROM or EEPROM of the device, and the corresponding function of the module can be implemented when the program code is executed by a processor. In addition, some functions of the module may need to be implemented by separate hardware or by working in cooperation with the hardware. For example, the detection function is implemented by a corresponding sensor (such as a proximity sensor, accelerometer, gyroscope, etc.), the signal transmission function is implemented by a corresponding communication device (such as a Bluetooth device, infrared communication device, baseband communication device, Wi-Fi communication device, etc.), the output function is implemented by a corresponding output device (such as a display, speaker, etc.), and so on.

[0028] To address the shortcomings in accuracy and uniformity of aerodynamic heat flux loading simulation in existing technologies for ultra-low orbit satellite ground thermal tests, this invention provides a calibration and control method for simulating aerodynamic heat flux in ultra-low orbit satellites. By constructing a multivariable feedback closed-loop control system, the current of each lamp is linked to the measured values ​​of each heat flux meter. The method utilizes PID control and the least squares iterative method based on the Jacobian matrix for solution, enabling refined and intelligent control of large-area, high heat flux density infrared lamp arrays and significantly improving the uniformity of heat flux loading.

[0029] Figure 1 A flowchart illustrating the calibration and control method for simulated aerodynamic heat flow in a very low Earth orbit satellite according to an embodiment of the present invention is shown. Figure 1 As shown, the calibration and control method for simulating aerodynamic heat flow in ultra-low orbit satellites provided by this invention includes the following steps: Step 101: Construct an infrared quartz lamp array and arrange a heat flux meter array at the heated surface. In one embodiment of the invention, a heat flux loading system is composed of dozens of infrared quartz lamp arrays. A schematic diagram of the overall heat flux loading lamp array is shown below. Figure 2 As shown. Figure 2As shown, the infrared quartz lamp array includes a top lamp array 201 and multiple side lamp arrays 202. The infrared quartz lamps used in the experiment are all strip-shaped heat sources, and 5-6 heat flow meters are placed on the heated surface to monitor the heat flow at each point. Sufficient safety distance is maintained between the lamps and the test system. Due to the dense lamp array and large heat flow, the heat flow loading system needs to be calibrated. The accuracy of the pneumatic heat flow loading during the experiment determines the reliability of the experimental results.

[0030] This invention uses heat flow meters to calibrate the actual heat flow value applied during the experiment. In one embodiment of this invention, the heat flow meters in the heat flow meter array can be adiabatic radiative heat flow meters, or simply adiabatic heat flow meters. Adiabatic heat flow meters operate based on the principle of radiative heat balance, calculating the heat flow value by measuring the temperature. To improve the accuracy of this heat flow meter, the measured temperature should be as unaffected as possible by background environmental interference, and heat conduction and radiative heat transfer from the sides and back should be isolated as much as possible. Figure 3 A schematic diagram of an adiabatic heat flow meter according to an embodiment of the present invention is shown. Figure 3 As shown, the adiabatic heat flow meter consists of a sensing element 303, a thermocouple 302, a multi-layer insulation assembly 304, a compensating element 301, and a base plate 305. The shell 306 is used to cover the side walls of each component. The multi-layer insulation assembly 304 is disposed between the compensating element 301 and the sensing element 303 to isolate conductive and radiative heat transfer in a vacuum environment, thereby effectively reducing heat exchange.

[0031] Step 102: Construct a multivariable feedback closed-loop control system, wherein the power supply current of each lamp in the infrared quartz lamp array is used as the input variable, and the measured value of each heat flow meter in the heat flow meter array is used as the output variable.

[0032] Figure 4 A schematic diagram of a multivariable feedback closed-loop control system according to an embodiment of the present invention is shown. Figure 4 As shown, the power supply current of each infrared lamp is the input condition for the normal operation of the entire experiment, and the measurement value of each heat flow meter is the output result of the experiment. The output result is processed by data processing and control algorithm to obtain new input and feed back to the entire experimental system, thereby completing feedback control.

[0033] Step 103: Based on the multivariable feedback closed-loop control system, perform the first heat flow calibration to optimize the power supply current distribution of each lamp.

[0034] Figure 5 A schematic diagram of the first heat flux calibration according to an embodiment of the present invention is shown. Figure 5As shown, the top and side light arrays were calibrated independently, with multiple heat flux meters (300) included in the figure. Five heat flux meters were installed in the top array, and six in the side arrays, covering the entire test area. The target temperature of the heat flux meters was calculated using the simulated aerodynamic heat flux values, and the power supply current to each lamp was adjusted to ensure uniform heat flux loading. The top and side heat flux calibrations needed to be performed separately to avoid mutual interference between the heat fluxes of the two arrays.

[0035] This invention simulates aerodynamic heat flow using an array of infrared quartz lamps in experiments, and places multiple heat flow meters at the heated surface to monitor the heat flow at various points. Calibration tests are required to adjust the power supply current of each lamp and control the uniformity of the total heat flow reaching the outer surface of the test piece, thereby ensuring the accuracy of the thermal test.

[0036] The first heat flux calibration involved obtaining an optimized solution for the power supply current distribution of each lamp in the infrared lamp array based on the aforementioned multivariable feedback control system. This included: establishing a transfer function from lamp current to heat flux density according to Planck's radiation law and Stefan-Boltzmann's law; dynamically adjusting the current of each lamp using a PID (Proportion Integration Differentiation) control algorithm; constructing a Jacobian matrix using calibration test data; and solving for the optimal current distribution that minimizes the deviation between the measured values ​​of each heat flux meter and the target heat flux value through linear least squares iterative approximation. Specific details are as follows.

[0037] A multi-layer thermal insulation assembly is installed between the compensation plate and the sensing plate to effectively reduce heat exchange in a vacuum environment. The heat balance equation of the heat flow meter, that is, the relationship between the surface temperature measured by the thermocouple and the heat flow reaching the infrared lamp array, is determined by the following formula: in, This indicates the heat flux from the lamp to the heat flow meter, expressed in W / m³. 2 ; This indicates the total absorption rate of the heat flow meter for the radiant energy emitted by the lamp. This represents the Stefan-Boltzmann constant, with a value of 5.67 × 10⁻⁶. -8 W / (m 2 K 4 ); Indicates the emissivity of the heat flow meter surface; This indicates the surface temperature of the heat flow meter, in Kelvin (K). Indicates multiplication.

[0038] Among them, total absorption rate The calculation formula is as follows: in, The absorption rate of the black varnish material of the heat flow meter to the energy in the λ spectral band can be obtained by measurement; express Radiant energy in the spectral band This represents the total radiated energy.

[0039] A transfer function from lamp current to heat flux density is established, based on Planck's radiation law and Stefan-Boltzmann's law, taking into account the lamp array geometry and radiation attenuation, and the heat flux density. It can be expressed by the following formula: Where N represents the number of fluorescent tubes. Indicates the hemispherical infrared emissivity; Represents the Stefan-Boltzmann constant. This represents the temperature of the i-th lamp (related to the lamp current). This represents the distance from the i-th lamp to the j-th heat flow meter. Indicates the radiation angle. Indicates the effective radiation area.

[0040] The current of each lamp is dynamically adjusted using PID control, and the objective function is defined as the root mean square error of the measured values ​​of each heat flux meter. for, Where M represents the number of heat flow meters, This represents the deviation between the measured value of the j-th heat flow meter and the target value. This indicates the target heat flux value set for each heat flux meter; in, It can be derived from the following formula, in, This represents the measured value of the j-th heat flow meter; The optimal lamp current solution is obtained by minimizing the objective function using the linear least squares iterative method.

[0041] Step 104: Perform the second heat flux calibration, using a contact heat source to calibrate the heat flux of the non-contact lamp array. The second calibration uses a more accurate contact heat source to further calibrate and fine-tune the non-contact heat flux of the infrared lamp array.

[0042] Figure 6 A schematic diagram of the aerodynamic heat flux calibration test procedure design according to an embodiment of the present invention is shown. Figure 6As shown, the first heat flow calibration is based on the optimized solution of the power supply current distribution of each lamp in the infrared lamp array obtained from the multivariable feedback control system described above. In the second heat flow calibration experiment, a calibration plate with compensated heating is designed to further calibrate the non-contact heat flow of the lamp array through contact heat flow. The calibration plate is a blackened metal plate with multi-layer heat insulation components on the back and ceramic heating elements (e.g., 4) and temperature sensors (e.g., 2) attached to the front. In the second heat flow calibration experiment, the first step is to turn off the infrared quartz lamp array and apply a known heat flow power to the calibration plate through contact heating with the ceramic heating elements, recording the first temperature value when steady state is reached. The second step is to turn off the ceramic heating elements, turn on the infrared quartz lamp array, heat the calibration plate through non-contact heating, adjust the lamp current until the temperature sensor reaches the first temperature value, and record the lamp current at this time as the final calibration result.

[0043] Step 105: Based on the lamp current determined by the second heat flow calibration, perform a system-level vacuum thermal test.

[0044] Figure 7 A schematic diagram of a system thermal test according to an embodiment of the present invention is shown. Figure 7 As shown, the system-level vacuum thermal test requires a space environment simulation device 701, a heat flow simulation apparatus, test fixtures, a programmable regulated DC power supply 705, a temperature data acquisition device 706, and a liquid nitrogen supply device 707. The heat flow simulation apparatus includes a top light array 201, a side light array 202, and a heat flow meter 704. The system-level vacuum thermal test is conducted in the space environment simulation device 701, which uses liquid nitrogen cooling. Liquid nitrogen pipelines are arranged on the side walls and front and rear end faces of the device to ensure that the temperature at different locations of the heat sink, i.e., the internal temperature of the space environment simulation device, is below -173℃. The inner surface of the space environment simulation device is coated with a black coating with an infrared emissivity higher than 0.88, and the internal pressure of the space environment simulation device is below 10. -3 Pa, this space environment simulation device can provide a vacuum cold black background environment for this thermal experiment. In one embodiment of the invention, the inner surface of the space environment simulation device is coated with an ERB-2 black coating with an infrared emissivity of 0.9. In one embodiment of the invention, the top light array, side light array, heat flow meter, experimental tank, and test specimen are all placed in the space environment simulation device. The top light array, side light array, and heat flow meter have been described above and will not be repeated here.

[0045] This invention also provides a calibration and control system for simulated aerodynamic heat flux of ultra-low orbit satellites. This system can be used in the aforementioned calibration and control method for simulated aerodynamic heat flux of ultra-low orbit satellites. The system includes: An infrared quartz lamp array, comprising a top lamp array and a side lamp array, is used to simulate the loading of aerodynamic heat flow onto the test specimen; A heat flow meter array is arranged on the heated surface of the test specimen to monitor the heat flow distribution in real time. A power supply, which is electrically connected to each lamp in the infrared quartz lamp array, is used to independently control the power supply current of each lamp; the power supply can be a programmable regulated DC power supply. A data acquisition device, electrically connected to the heat flux meter array, is used to acquire heat flux measurement data; The control unit is communicatively connected to both the power supply and the data acquisition device, and is configured to perform the steps in the calibration and control method for simulated aerodynamic heat flow of the ultra-low orbit satellite.

[0046] In one embodiment of the present invention, the control unit includes a PID controller and an iterative optimization module. The PID controller is used to dynamically adjust the lamp current according to the heat flow deviation, and the iterative optimization module is used to construct the Jacobian matrix and iteratively solve the optimal current distribution using the linear least squares method.

[0047] In one embodiment of the present invention, the calibration and control system for simulating aerodynamic heat flow in ultra-low orbit satellites also includes space environment simulation equipment, temperature control equipment, etc.; the infrared quartz lamp array, heat flow meter array, experimental tank, and test piece are all placed in the space environment simulation equipment; the temperature control equipment can be a liquid nitrogen supply device.

[0048] This invention proposes a calibration and control method for simulating aerodynamic heat flux in ultra-low orbit satellites. The first heat flux calibration addresses the issue of uniform heat flux distribution in the lamp array. The second heat flux calibration uses a contact heating source for comparative calibration, effectively eliminating systematic errors in non-contact heating systems and ensuring the absolute accuracy of heat flux loading. This dual guarantee mechanism of uniformity and accuracy significantly improves the reliability of ground tests. A high-precision adiabatic heat flux meter is designed, effectively isolating heat exchange on non-target surfaces through multi-layer insulation components. Combined with a precise heat balance equation, it provides accurate and reliable feedback signals for the closed-loop control system, forming the foundation for precise control. It is particularly suitable for high heat flux density simulation tests at levels of 5000 W / m² and above, solving key technical challenges in ultra-low orbit satellite thermal testing and possessing significant engineering application value.

[0049] Although various embodiments of the present invention have been described above, it should be understood that they are presented by way of example only and not as limitations. It will be apparent to those skilled in the art that various combinations, modifications, and alterations can be made without departing from the spirit and scope of the invention. Therefore, the breadth and scope of the invention disclosed herein should not be limited by the exemplary embodiments disclosed above, but should be defined according to the technical solutions of the invention and their equivalents.

Claims

1. A method for calibrating and controlling simulated aerodynamic heat flux in ultra-low orbit satellites, characterized in that, Includes the following steps: Construct an array of infrared quartz lamps and arrange an array of heat flow meters at the heated surface; A multivariable feedback closed-loop control system is constructed, wherein the power supply current of each lamp in the infrared quartz lamp array is used as the input variable, and the measured value of each heat flow meter in the heat flow meter array is used as the output variable. Based on the multivariable feedback closed-loop control system, the first heat flow calibration is performed to optimize the power supply current distribution of each lamp. Perform a second heat flux calibration, using a contact heat source to calibrate the heat flux of the non-contact lamp array; and Based on the lamp current determined by the second heat flow calibration, a system-level vacuum thermal test is performed.

2. The calibration and control method for simulating aerodynamic heat flow in ultra-low orbit satellites according to claim 1, characterized in that, The first heat flux calibration includes: The top light array and the side light array were calibrated independently. Target heat flux values ​​are set for each heat flux meter based on simulated aerodynamic heat flux values; and The current of each lamp is dynamically adjusted by a PID control algorithm, and the Jacobian matrix is ​​constructed using calibration test data. The optimal current distribution that minimizes the deviation between the measured values ​​of each heat flow meter and the target heat flow value is solved by linear least squares iterative approximation.

3. The calibration and control method for simulating aerodynamic heat flow in ultra-low orbit satellites according to claim 1, characterized in that, The second heat flux calibration includes: A calibration plate with compensated heating is provided. The calibration plate has a multi-layer heat insulation component on the back and a ceramic heating element and a temperature sensor attached to the front. The infrared quartz lamp array is turned off, and a known heat flux is applied to the calibration plate via contact heating through the ceramic heating element. The first temperature value at which steady state is reached is recorded. Disconnect the ceramic heating element, start the infrared quartz lamp array, heat the calibration plate in a non-contact manner, adjust the lamp current until the temperature sensor reaches the first temperature value, and record the lamp current at this time as the final calibration result.

4. The calibration and control method for simulating aerodynamic heat flow in ultra-low orbit satellites according to claim 1, characterized in that, The heat flow meter in the heat flow meter array is an adiabatic heat flow meter, which includes a sensitive element, a thermocouple, a multilayer insulation component, a compensating element, and a base plate. The multilayer insulation component is disposed between the compensating element and the sensitive element to isolate conductive and radiative heat transfer in a vacuum environment.

5. The calibration and control method for simulating aerodynamic heat flow in ultra-low orbit satellites according to claim 4, characterized in that, The heat balance equation for the adiabatic heat flow meter is established, and the relationship between the surface temperature measured by the thermocouple and the arriving heat flow is determined by the following formula: in, This indicates the heat flow from the lamp to the heat flow meter. This indicates the total absorption rate of the heat flow meter for the radiant energy emitted by the lamp. Represents the Stefan-Boltzmann constant. Indicates the emissivity of the heat flow meter surface. This indicates the surface temperature of the heat flow meter. Indicates multiplication; Among them, total absorption rate The calculation formula is as follows: in, The absorption rate of the black varnish material of the heat flow meter to the energy in the λ spectral band can be obtained by measurement; express Radiant energy in the spectral band This represents the total radiated energy.

6. The calibration and control method for simulating aerodynamic heat flow in ultra-low orbit satellites according to claim 1, characterized in that, A transfer function from lamp current to heat flux density is established, based on Planck's radiation law and Stefan-Boltzmann's law, and taking into account the lamp array geometry and radiation attenuation, and heat flux density. It can be expressed by the following formula: Where N represents the number of fluorescent tubes. Indicates hemispherical infrared emissivity, Represents the Stefan-Boltzmann constant. This represents the temperature of the i-th lamp. This represents the distance from the i-th lamp to the j-th heat flow meter. Indicates the radiation angle. Indicates the effective radiation area.

7. The calibration and control method for simulating aerodynamic heat flow in ultra-low orbit satellites according to claim 2, characterized in that, The current of each lamp is dynamically adjusted using PID control, and the objective function is defined as the root mean square error of the measured values ​​of each heat flux meter. for, Where M represents the number of heat flow meters, This represents the deviation between the measured value of the j-th heat flow meter and the target value. This indicates the target heat flux value set for each heat flux meter; in, It is derived from the following formula, in, This represents the measured value of the j-th heat flow meter; The optimal lamp current solution is obtained by minimizing the objective function using the linear least squares iterative method.

8. The calibration and control method for simulated aerodynamic heat flow of ultra-low orbit satellites according to claim 1, characterized in that, The system-level vacuum thermal test was conducted in a space environment simulation device, the internal pressure of which was below 10. −3 Pa, the internal temperature of the space environment simulation device is below -173℃, and the inner surface of the space environment simulation device is coated with a black coating with an infrared emissivity higher than 0.

88.

9. A calibration and control system for simulated aerodynamic heat flux of a very low Earth orbit satellite, used in the calibration and control method for simulated aerodynamic heat flux of a very low Earth orbit satellite as described in any one of claims 1-8, characterized in that, include: An infrared quartz lamp array, comprising a top lamp array and a side lamp array, is used to simulate the loading of aerodynamic heat flow onto the test specimen; A heat flow meter array is arranged on the heated surface of the test specimen to monitor the heat flow distribution in real time. A power supply, which is electrically connected to each lamp in the infrared quartz lamp array, is used to independently control the power supply current of each lamp. A data acquisition device, electrically connected to the heat flux meter array, is used to acquire heat flux measurement data; A control unit, which is communicatively connected to the power supply and the data acquisition device, is configured to perform the steps in the calibration and control method for simulating aerodynamic heat flow of a low-Earth orbit satellite as described in any one of claims 1-8.

10. The system according to claim 9, characterized in that, The control unit includes a PID controller and an iterative optimization module. The PID controller is used to dynamically adjust the lamp current according to the heat flow deviation, and the iterative optimization module is used to construct the Jacobian matrix and solve the optimal current distribution iteratively using the linear least squares method.

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