| With the development of manned spaceflight,astronaut’s extravehicular activity is becoming more and more frequent.Extravehicular environment is very bad,so astronaut must be protected in the closed micro-environment of extravehicular spacesuit to live and work.Extravehicular spacesuit is different with intravehicular spacesuit in structure modeling and operating requirements.Extravehicular spacesuit’s functions and environmental requirements are more complicated than intravehicular spacesuit,and the factors needed to be evaluated and measured in thermal property aspect are much more.So the present intravehicular spacesuit thermal manikin can not meet the requirements of extravehicular spacesuit.It is necessary to systematically study the thermal manikin used in measurement of extravehicular spacesuit.This paper studied the comprehensive performance and application of a novel extravehicular spacesuit thermal manikin and its simulated skin. The optimal simulated skin was determined by elastomer soft materials’ synthetic performance test and fuzzy mathematics theory analysis.Meanwhile,based on heat transfer theory,the theoretical analysis and experimental verification were performed on simulated skin’s steady and unsteady heat transfer.By this novel thermal manikin, the heat transfer of extravehicular liquid cooling garment was analyzed,and the heat transfer model was established in the states of manikin covered with simulated skin and without covered with simulated skin.Based on the model,the relations between liquid cooling garment’s design parameters and heat removing as well as that between the design parameters and heat transfer efficiency were discussed.Finally, the first order differential equation prediction models of liquid cooling garment’s heat removing and heat transfer efficiency were established by grey system theory.The contents and results were described following: (1) The basic function of the novel extravehicular spacesuit thermal manikin and the structure,design principle and characteristics of manikin’s subsystems——shell of manikin,measurement and control system,assisted suspension,were detailed described.Meanwhile,based on lots of experiments,the comprehensive performance of thermal manikin system was analyzed and evaluated,including stability,dynamic response property and accuracy.In the case of relatively stable testing conditions,the stability of thermal manikin was analyzed by the change law of temperature in inner and outer surfaces of manikin,power consumed and insulation value measured by naked thermal manikin.And the influence of environmental temperature,relative humidity and wind velocity on thermal manikin’s stability was analyzed by grey relational degree analysis in grey system theory.In the case of changeable environmental condition or changeable thermal manikin state,manikin’s dynamic response process was analyzed by the changes of temperature in inner and outer surfaces of manikin.In thermal manikin’s accuracy analysis,the repeatability of insulation value measured by thermal manikin was studied,and the accuracy of air layer’s insulation value was analyzed based on the definition of clo value.(2) The newly elastomer materials in polymer soft material field were selected to be alternative simulated skin used in extravehicular spacesuit thermal manikin.The experiments of materials’ physical properties and chemical stability were performed and 16 terms of performance indexes were measured.To evaluate the comprehensive property of each alternative material,the fuzzy mathematics theory was used to do fuzzy decision-making.By synthetic analysis of many kinds of fuzzy decision-making methods,the optimal simulated skin material used in thermal manikin was finally determined.The stability and accuracy of thermal manikin in the state of thermal manikin covered with simulated skin were analyzed and compared with the state of thermal manikin without covered with simulated skin.(3) Research of steady heat transfer and unsteady heat transfer of simulated skin in extravehicular spacesuit thermal manikin was performed.In steady heat transfer analysis,the simulated skin was divided into two classes according to the shape of different manikin sections,which were chest-back section’s simulated skin,analyzed by semi-infinite plate heat transfer theory,and other sections’ simulated skin, analyzed by long cylinder heat transfer theory.The heat transfer differential equation and heat balance equation of simulated skin in these two states were established,and the experimental verification was performed.In a certain environmental condition and at a constant temperature of thermal manikin covered with simulated skin,the power consumed and the temperature in outer surface of simulated skin were measured,and the comparative analysis of experimental results and theoretical results shows that simulated skin’s steady heat transfer analysis has a high precision.In simulated skin’s unsteady heat transfer analysis,because the unsteady heat transfer analysis method on semi-infinite plate and long cylinder was the same,the chest-back section’s simulated skin was analyzed as an example,and the heat transfer equation was established.The equation was solved by finite difference method in numerical solution,and the explicit finite difference scheme temperature equations of simulated skin’s internal node and boundary node were established.By computer iterative calculation,the temperature variation curves of simulated skin’s outer boundary node were obtained,and the experimental verification was performed.In a certain environmental condition and at a constant temperature of thermal manikin covered with simulated skin,the real time changes of temperature in outer surface of chest-back section’s simulated skin were measured,and the comparative analysis of experimental results and theoretical results shows that simulated skin’s unsteady heat transfer analysis has a high precision.(4) The heat transfer of extravehicular liquid cooling garment used for extravehicular activity was analyzed based on extravehicular spacesuit thermal manikin and its simulated skin.The liquid cooling garment’s heat transfer models were established in the states of manikin covered with simulated skin and without covered with simulated skin.The heat transfer expression of liquid cooling garment with thermal manikin and with air layer,and the expression of liquid cooling garment’s heat removing and heat transfer efficiency were obtained,meanwhile,the experimental verification was performed.In a certain environmental condition and at a constant temperature of thermal manikin covered with simulated skin and wearing liquid cooling garment,liquid cooling garment’s heat removing was measured,and the comparative analysis of experimental results and theoretical results shows that the liquid cooling garment’s heat transfer model has a high precision.Based on the model, the relations between liquid cooling garment’s three design parameters(inlet temperature,flow velocity and tube length) and heat removing,as well as that between the design parameters and heat transfer efficiency were discussed.Results show that the relations in the states of manikin covered with simulated skin and without covered with simulated skin are the same.And under the same condition, when thermal manikin is covered with simulated skin,liquid cooling garment’s heat removing and heat transfer efficiency will be improved.Because the solution of liquid cooling garment’s heat transfer model was complicated,in order to make it easier,the first order differential prediction models of liquid cooling garment’s heat removing and heat transfer efficiency by inputting three design parameters were established in the states of thermal manikin covered with simulated skin and without covered with simulated skin by grey modeling method in grey system theory.By relative residual test,the model’s prediction precision is so high as to surpass 95%. |
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