Structural Design And Experimental Verification Of High Temperature Seal

Due to the phenomenon of gap flow and aerodynamic heating during the re-entry of space vehicles,no matter for cruise and glide vehicles,re-entry warheads or manned spacecraft,the control surface and the opening gaps of the fuselage all need to be heat sealed.The main way to realize the thermal seal is to fill the gap with heat insulation sealing material,which produces two kinds of high temperature thermal seal structure forms: baseline seals and Ceramic wafer seals.Since the GRC research center of NASA started the research on thermal seal in the late 1980 s,there have been relatively few studies on this aspect in China,and the preparation technology of high-temperature thermal seal is not perfect yet.However,with the development of space technology,the development of reusable vehicle and hypersonic vehicle’s key technology of high temperature thermal sealing technology has become the weak link of thermal protection system and one of the core issues that need to be solved urgently.On the issue of the aircraft door gap seal,in this paper,the author designed an improved heat sealing structure,explored the comprehensive the preparation technology of baseline high temperature heat seal.In addition,an experimental platform was designed for the high temperature resilience and insulation of thermal seals,and the key parameters affecting the mechanical properties of their elastic components were explored.In this paper,based on the traditional baseline high temperature thermal seal structure,in order to improve the material integrity of the internal core and the resilience energy of components,the structural forms of inner heat insulation layer core,braid spring,outer heat insulation layer and casing are proposed.In addition,the preparation of each component is also explored in detail.On the insulating layer type packing is explored for the preparation of weaving process,loose cotton core filling body and fiber coated core technology,for the preparation of weaving spring explores the close type weave,double wire weaving weaving process,such as additional external heat insulation layer and the preparation of cladding layer and the preparation methods of overall heat seal is made a thorough exploration and research.The compression elastic energy of braided spring is studied.Based on the establishment of the analysis model,this paper explores the influence of these parameters on the compression stiffness of braided spring through a series of tests on key parameters such as pipe diameter,wire diameter and braided density,and obtains the relationship between these parameters and compression stiffness through numerical fitting.Aiming at the normal temperature and high temperature elastic energy test of high temperature thermal seals,a thermally coupled platform with mechanical testing machine and high frequency induction heating for atmospheric environment was designed,and the elastic energy test research was carried out for different stru ctural schemes designed.In the thermal insulation properties of the materials,on the basis of the qualitative comparison experiment was carried out through design to keep high temperature heat seal compression state of the test fixture,using quartz lamp array heating equipment solutions for different materials of high temperature heat seal test,the performance of insulation by comparing the test results and the appearance of the structure characteristics,select the best material structure scheme,and a ccording to the core body of different preparation technology on the study of comparative tests.Repeated tests were carried out on the high temperature reusable performance of high temperature thermal seals,and the test results showed that the expected index requirements were met.