The energy equilibrium equation and discrete ordinate methods are combined to establish the one-dimensional steady heat transfer mathematical model of multi-layer thermal insulations （MTIs） in metallic thermal prote...The energy equilibrium equation and discrete ordinate methods are combined to establish the one-dimensional steady heat transfer mathematical model of multi-layer thermal insulations （MTIs） in metallic thermal protection systems. The inverse problem of heat transfer is solved by the genetic algorithm and data from the steady heat transfer experiment of fibrous thermal insulations. The density radiation attenuation coefficient, the albedo of fibrous thermal insulations and the surface emissivity of reflective screens are optimized. Finally, the one-dimensional steady heat transfer model of MTIs with optimized thermal physical parameters is verified by experimental data of the effective MTI conductivity.展开更多
A composite coating with inner and outer layers was prepared for the thermal protection of woven silica fiber fabrics.Using a sol mixture of a silica sol and AlF3/SiO2 particles mixed in the stoichiometric molar ratio...A composite coating with inner and outer layers was prepared for the thermal protection of woven silica fiber fabrics.Using a sol mixture of a silica sol and AlF3/SiO2 particles mixed in the stoichiometric molar ratio for mullite,hollow silica spheres and short mullite fibers were added to the inner layer and outer layer,respectively.The phase composition and thermal evolution of the coating,along with the interfacial microstructure between the coating and the matrix,were characterized by means of X-ray diffraction,differential scanning calorimetry/thermogravimetry,scanning electron microscopy,and tensile strength testing.Mullite whiskers grew between 950°C and 1200°C and helped prevent thermal cracking during the drying and densification processes.The hollow silica spheres might play dual roles,weakening the adhesion between the coating and the fibers by reducing their direct contact,but strengthening the joining between the coating and substrate by embedding themselves among the fabrics.展开更多
文摘The energy equilibrium equation and discrete ordinate methods are combined to establish the one-dimensional steady heat transfer mathematical model of multi-layer thermal insulations （MTIs） in metallic thermal protection systems. The inverse problem of heat transfer is solved by the genetic algorithm and data from the steady heat transfer experiment of fibrous thermal insulations. The density radiation attenuation coefficient, the albedo of fibrous thermal insulations and the surface emissivity of reflective screens are optimized. Finally, the one-dimensional steady heat transfer model of MTIs with optimized thermal physical parameters is verified by experimental data of the effective MTI conductivity.
基金supported by the National Natural Science Foundation of China(Grant Nos.51272171,51372164)
文摘A composite coating with inner and outer layers was prepared for the thermal protection of woven silica fiber fabrics.Using a sol mixture of a silica sol and AlF3/SiO2 particles mixed in the stoichiometric molar ratio for mullite,hollow silica spheres and short mullite fibers were added to the inner layer and outer layer,respectively.The phase composition and thermal evolution of the coating,along with the interfacial microstructure between the coating and the matrix,were characterized by means of X-ray diffraction,differential scanning calorimetry/thermogravimetry,scanning electron microscopy,and tensile strength testing.Mullite whiskers grew between 950°C and 1200°C and helped prevent thermal cracking during the drying and densification processes.The hollow silica spheres might play dual roles,weakening the adhesion between the coating and the fibers by reducing their direct contact,but strengthening the joining between the coating and substrate by embedding themselves among the fabrics.
