Numerical Simulation Of Thermal Radiation Characteristics Of SiO₂ Ceramic Fiber Fabric Based On FDTD Method

With the development and progress of science and technology,composite materials have become more and more widely used.Due to the excellent performance of SiO₂fiber,it is used as the raw material of various composite materials,and SiO₂ fiber is combined with different matrix to form composite material.In the aviation field,the surface pressure of an aircraft changes drastically during the flight,and the surface temperature rises rapidly.The temperature on the windward surface can reach up to 1000°C.A large amount of heat endangers safety and causes safety accidents.It can be seen that the silica ceramic fiber plays an important role in the thermal protection system of the aviation field.Through the research on the thermal radiation performance of the three-dimensional braided silica fiber composite material,the analysis of the factors affecting the thermal radiation performance of the material provides a theoretical basis for improving the structure of the composite material and improving the thermal radiation performance,and is useful for improving the thermal protection of spacecraft.Important role.This paper selects the silica fiber bundle weaving structure as the research object,and uses the finite difference time domain method to simulate the silica ceramic fiber material.In the study,two-dimensional and three-dimensional structure models were established.Under the two-dimensional structure model,the scattering,absorption cross-section,transmittance and reflectivity of silica fibers in different arrangements and different contents were calculated,and the structure and content of the material were analyzed.Influence of radiation performance.Under the three-dimensional structure model,a three-dimensional two-way,orthogonal,four-way,five-way,six-way,and seven-way weave structure was established.For the six weave structures,five different contents and six different temperatures were calculated for scattering and absorption.Cross-section,transmittance and reflectance,analyze the degree of influence of different contents and different temperatures on material properties.Discuss the scattering and absorption efficiency of silica fiber with three-dimensional woven structure.The influence of temperature on the radiation characteristics of the material is analyzed;the electromagnetic field distribution of the silica fiber material with the same content and different structure is calculated.Research has found that the content of silica fiber has a different effect on the thermal radiation performance of the material,and the content has a greater impact on the scattering performance of the material;the transmittance of the material gradually decreases with the increase of the content,and the reflectivity gradually increases;When the content is the same,the three-dimensional seven-directional woven material has the largest scattering cross section and the best heat dissipation performance among the six woven structures.The three-dimensional five-directional woven silica fiber has the largest absorption cross section and the material has the best absorption efficiency;When the content is the same,the reflectivity of the three-dimensional seven-way woven silica fiber is the best;the scattering performance of the three-dimensional two-way woven silica fiber is better at high temperature,and the temperature has a greater impact on the absorption performance of the three-dimensional woven material.The influence of temperature on the transmittance of the three-dimensional four-way woven silica fiber does not show a large regularity,and other structures show certain regularities.In general,the temperature has a greater influence on the reflectance of the material;The electromagnetic fields of the six braided structures are mainly distributed in the position of the braided fiber bundles.The electromagnetic field strength of the inner fiber bundles is smaller than that of the outer fiber bundles,and the inner electromagnetic field strength of the fiber bundles is the smallest.