Numerical Simulation Of Spectral Radiation Characteristics Of Carbon Fiber Composites Based On FDTD Method

High-temperature flames and high-speed aircraft flying with air will generate a lot of heat,and the release of huge heat from the heat source will bring safety hazards and cause safety accidents.Good thermal protection can improve the safety of high-speed aircraft and avoid disintegration accidents caused by heat.Carbon fiber has good heat resistance and corrosion resistance,and is widely used in the thermal protection of high-speed aircraft and spacecraft.Theoretical calculations based on spectral radiation characteristics can provide a theoretical basis for improving material structure and enhancing thermal protection.In this paper,the finite difference time domain method(Finite Difference Time Domain)method is used to establish the physical model of parallel vertical arrangement of carbon fibers(2D random arrangement)and non-parallel arrangement of carbon fiber longitudinal axes(3D random arrangement)according to the literature.Determine the accuracy of the simulation calculation grid.According to the influence of the random arrangement of carbon fiber,content and radius on its spectral radiation characteristics,calculate the four different content of equal radius and non-equal radius in three random arrangement modes,the carbon fiber is 2.5?mTrends in scattering and absorption factors in the 15 ?m band.For the structural arrangement,the analysis compares the random arrangement and uniform arrangement,the relative deviation of 3D random arrangement and 2D random arrangement on carbon fiber scattering,absorption factor or scattering and absorption cross section.The influence of matrix on the spectral radiation characteristics of carbon fiber composites was calculated and analyzed.The SiC matrix and Mg matrix were added into carbon fiber,and the scattering and absorption factors of carbon fiber composites were changed after carbon nanotubes were added into SiC matrix.The results show that the carbon fiber content,arrangement,radius and matrix will affect the spectral radiation characteristics of carbon fiber and its composite materials.The uniform arrangement model replaces the random arrangement model,and the 2D random arrangement replaces the 3D random arrangement calculation.The carbon fiber scattering factor and the absorption factor are greatly deviated,and the influence of the random arrangement of the carbon fiber on the spectral radiation characteristics is not negligible.In-depth analysis of the spectral radiation characteristics of carbon fiber composites can provide a theoretical basis for improving the structure of carbon fiber and its composite materials,making it better used in thermal protection.