Space subsystems design: (navigation, control, structure and…)
Hamed Ramezani Najafi; S.M.Hossein Karimian; Mohammad Reza Pakmanesh
Volume 16, Issue 1 , March 2023, , Pages 11-21
Abstract
One of the passive components of the satellite Thermal control subsystem is multilayer insulation. In order to prevent air from being trapped between the multilayer insulation layers, which causes the thin layers to inflate and disintegrate during satellite launches, holes are made in the layers. These ...
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One of the passive components of the satellite Thermal control subsystem is multilayer insulation. In order to prevent air from being trapped between the multilayer insulation layers, which causes the thin layers to inflate and disintegrate during satellite launches, holes are made in the layers. These holes in different layers may not be aligned due to heat transfer problems as well as manufacturing constraints. For maximum thermal efficiency of thermal insulation, gas outlets must be designed to have the least resistance to exhaust gas flow, because the air trapped between the layers will greatly reduce the insulation efficiency by leaving a convective heat transfer path between them. In this article, different perforation matrix that have been used in articles are reviewed. By analyzing the computational fluid dynamics of gas outflow from these insulators, the effect of various parameters has been studied.
hamed Alisadesghi; Hamed Ramezani-Najafi; Hossein Reza Abbasi
Volume 9, Issue 2 , September 2016, , Pages 61-76
Abstract
Base on space standards, the thermal design evaluations for satellites are performed using thermal balance tests. Regularly, the thermal model is used for the thermal balance test. This model is completely similar to the flight model of the satellite in terms of thermal characteristics. In this paper, ...
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Base on space standards, the thermal design evaluations for satellites are performed using thermal balance tests. Regularly, the thermal model is used for the thermal balance test. This model is completely similar to the flight model of the satellite in terms of thermal characteristics. In this paper, the definition and implementation of thermal balance tests for Thermal model of AUTSAT Satellite is conducted. the evaluation of the TM and the procedure data Correlation of the numerical model have been focused. In order to increase the accuracy and feasibility of thermal mathematical model correlation, structural and complete models are considered for the balance test separately. In this study, the results of thermal balance test for the structural thermal model has been compared with the numerical analysis and the correlation procedure is illustrated. The results achieved by this procedure shows that all the requirements by the standard are satisfied in this level.
Hamed R. Najafi; Esmaiel Moeini; Seyed Mohammad Hossein Karimian; Hamed Alisadeghi
Volume 8, Issue 1 , April 2015, , Pages 19-25
Abstract
The intention of this paper is to discuss the results obtained from tests conducted at Amirkabir University of Technology Thermal Control Lab on multilayer insulation (MLI) blankets designed and fabricated in university, describing the thermal performance of test specimens at different environmental ...
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The intention of this paper is to discuss the results obtained from tests conducted at Amirkabir University of Technology Thermal Control Lab on multilayer insulation (MLI) blankets designed and fabricated in university, describing the thermal performance of test specimens at different environmental temperatures. We have evaluated the MLI performance by experimentally measuring our MLI’s emissivity factor. For this purpose we have defined our experiments based on the effective emissivity model. Fabricated MLI blankets are tested in a vacuum chamber at an approximate pressure of 10-6mbar and temperatures of approximately 30°C and -70°C, while subjected to heat with the power input in the range of 1.0 to 2.5 Watts. Results show that the measured effective emissivity is within the range of other reported experimental data.
