Heat control
Mehrnoosh Farahani; Vafa Sedghi; seyed mostafa safavi homami; Hamid Mesforoush
Abstract
The ions in the space environment cause the surface and internal charging phenomenon in satellites. The accumulated potential during the charging phenomenon can cause electrostatic discharge and expose the satellite telecommunication components such as antennas and electronic circuits to serious ...
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The ions in the space environment cause the surface and internal charging phenomenon in satellites. The accumulated potential during the charging phenomenon can cause electrostatic discharge and expose the satellite telecommunication components such as antennas and electronic circuits to serious risk. The purpose of this paper is to investigate the possibility of electrostatic discharge on satellite surfaces in low earth orbit (LEO) environment and to reduce this possibility in order to reduce the risk of damage to satellite surfaces and telecommunication components. Therefore, First, the surface charging phenomenon was simulated in an aluminum satellite in low earth orbit and then in polar aurora by SPIS software and the possibility of damage to the antennas was investigated. Then, multi-layer thermal insulation was applied to the system and its effects on the charging phenomenon were investigated. Research has shown that adding MLI layers will increase the risk of electrostatic discharge. Therefore, in the next steps, the effect of the grounding system in reducing the risk was investigated. By connecting the layers to the ground in a proper way, the possibility of discharge between the layers and the body and between the layers with each other is minimized, which led to the achievement of an optimal system in terms of electrostatic aspects
Heat control
Nematollah Fouladi; Mohammad Farahani; Milad Mahdian Dowlatabadi
Abstract
The aim of this study is to evaluate the performance of water-jacket cooling system for thermal protection of exhaust large dimension diffuser at high heat fluxes in a wide range of coolant pressure. For this purpose, using the developed calculation code, the parameters of the water-jacket cooling system ...
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The aim of this study is to evaluate the performance of water-jacket cooling system for thermal protection of exhaust large dimension diffuser at high heat fluxes in a wide range of coolant pressure. For this purpose, using the developed calculation code, the parameters of the water-jacket cooling system are determined so that in addition to satisfying the temperature conditions of the metal body, the total pressure drop has remained in the desired range. In the following, the capability of numerical code to design and performance analysis of the cooling system has been evaluated in coolant pressure of 3 to 50 bar and high heat fluxes up to 3.5 MW/m2. The present studies show that the proper selection of coolant pressure is very important in the design of the cooling system with optimal mass flow rate and minimum coolant dimensions, especially at high heat fluxes, so that increasing the coolant pressure from 3 to 10 bar, in addition to significantly reducing the dimensions of the cooling system, reduces the mass flow rate by 75%.
Heat control
Mohamad Reza Nasresfahani; Mohamad Nasresfahani; hossein Nazemi; mojtaba forghani; hadi gorabi
Abstract
One of the most common methods to increase the adhesion of aluminum surfaces is the use of anodized coatings. However, if we heat the manufactured products before adhering due to the hydration of the anodized coating, cracking and morphological changes, the adhesive capacity will be severely reduced. ...
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One of the most common methods to increase the adhesion of aluminum surfaces is the use of anodized coatings. However, if we heat the manufactured products before adhering due to the hydration of the anodized coating, cracking and morphological changes, the adhesive capacity will be severely reduced. As part of the research presented in this study, methods such as non- sealing of the anodize, primer application before heating the coating, sandblasting before and after the anodizing coating, and use of FPL (Forest Products Laboratory) replacement coating have been used to investigate the adhesive behavior of the coating. According to the results, not sealing the anodized coating and priming it before heating will increase the adhesiveness of the coating in all cases. Sandblasting after coating had no significant effect on adhesion. Sandblasting before anodizing improves adhesion by altering the texture of roughness and morphology. FPL can also be used to replace anodized coatings. They were less sensitive to heating and storage
