| The Variable attitude dual-band integrated space camera has visible and infrared dual-band imaging channels.Compared to the visible single-band optical payload,dualband cameras can capture more information,not only can simultaneously obtain highresolution visible and infrared images,but also uninterrupted observation during the day and night,and consequently could achieve all-day imaging of the Earth,the development of dual-band integrated space camera has important application value.The thermal control system is an important guarantee for the space camera to obtain high quality images.In this thesis,the key technology of thermal control of this camera is studied for the variable-attitude dual-band integrated space camera as the research object.Firstly,this thesis summarizes the development and research of thermal control technology of typical domestic and foreign near-Earth orbit spacecraft.Further,the thermal design task of the variable-attitude dual-band integrated space camera studied in this thesis is analyzed,and the key and difficult problems of thermal control,such as the complex flight attitude of the camera,the high-power internal heat source for long-term operation needs efficient heat dissipation and infrared calibration of the black body requires high precision temperature control emphasis and difficult problems.Secondly,the space environment of the variable-attitude dual-band integrated space camera is analyzed.The camera operates in a near-Earth circular orbit,and there is no stable back shaded side during its on-orbit operation,and all sides may be illuminated,moreover,the camera’s flight attitude is variable,which makes the external heat flow to its surface complex,hence it is necessary to analyze the external heat flow in all directions of the camera to provide important references for the subsequent thermal control system design,extreme operating conditions definition and thermal simulation calculation.Using the orbital parameters of the camera,the variation curve of the angle between the orbital plane and the sunlight vector(β angle)are calculated,and the trend of the external heat flow with β angle is analyzed in conjunction with the orbital attitude of the camera to guidance the selection of the directions of the heat sink surface and the definition of the extreme analysis conditions.The results indicate that the ±X-plane has a stable back shaded side during the orbital operation and arrives at a smaller external heat flow,which is more appropriate for the setting direction of the heat sink.Then,the detailed thermal design of the main optical machine structure of the variable-attitude dual-band integrated space camera is carried out.Then,the detailed thermal design of the main optical machine structure of the variable-attitude dual-band integrated space camera is carried out.According to the thermal control index of the camera optical structure,the structural characteristics of each component are analyzed,and the thermal design of the camera optical structure is carried out by combining active and passive thermal control measures.For the visible optics reflector group,the indirect radiation temperature control is adopted to ensure the temperature level and temperature uniformity of the reflector lens,and the infrared calibration blackbody adopts a temperature measurement and control system composed of platinum resistance and active heating circuit,and adopts a polyimide thermal insulation pad and multi-layer thermal insulation components for thermal isolation,so that it can meet the requirements of high precision temperature control of the infrared calibration blackbody.At the same time,the heat dissipation design of the internal heat source of the camera is designed to address the problem of excessive peak power consumption.Combined with the camera structure design and satellite platform distribution,channel heat pipes and radiation cooling plates are used to dissipate heat from the internal heat source.According to the thermal control index and working mode of the internal heat source,the radiation cooling plate is designed in blocks.For the hot end component of the cooler with large heat output,a double-sided radiative cold plate coupling design is adopted to take advantage of the feature of having a stable backside in the ±X direction during camera operation,which can effectively increase the heat dissipation efficiency and reduce the area of the single-sided radiative cold plate to meet its heat dissipation requirements.After that,the thermal simulation analysis of the whole camera was carried out.Combining the characteristics of the external heat flow of the camera with the extreme working conditions of the flight attitude determination thermal analysis,and then using the finite element simulation software to establish the thermal simulation model of the camera and calculate the temperature distribution of each component of the camera under each working condition,the results show that the temperature of the main bearing structure of the camera in the working mode is 17.2℃～19.3℃,the temperature of the visible optical system is 18.04℃～18.29℃,the infrared optical system is The maximum temperature difference of the infrared calibration blackbody during calibration work is0.5℃,the maximum temperature rise time is 30 s in normal temperature calibration mode,and the maximum temperature rise time is 150 s in high temperature calibration mode.the temperature range of the visible focal plane assembly is-1.9℃～12.9℃,the temperature range of the infrared camera circuit board assembly is 1.7℃～10.5℃,and the temperature range of the chiller compressor assembly The temperature range is-12℃～21.3℃,and the temperature range of the hot end component of the cooler is-12.2℃～0.3℃.In addition,the temperature of the internal heat source meets the index requirements in the non-working mode when the camera is in the standby condition and the storage condition.Finally,the thermal equilibrium test of the camera optical structure was carried out.The results show that the active thermal control system can ensure the temperature level of the main optical structure under high and low temperature conditions,and the temperature of the main optical structure meets the thermal control index requirements,which verifies the reasonableness of the thermal design of the camera optical structure. |
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