The Study Of Equivalent Thermal Conductivity Of Composite Material Under The Radiation-conduction Coupled Heat Transfer

The low thermal conductivity properties of carbon fiber composite materials make them applied widely in thermal protection, and any object above absolute zero is emitting and absorbing radiant energy, especially at high temperatures. Lattice Boltzmann method is one of the most promising simulation in the field of fluid mechanics and heat transfer and it is also feasible in research on radiation and heat conduction coupled heat transfer problems.From theory, based on the lattice Boltzmann method, this article simulates heat conduction and conduction-radiation thermal coupling for five typical structures of carbon fiber composite materials, for different typical woven structures like 90 degrees two dimensional weaving, chopped carbon fibers randomly arranged, arranged parallel to each other axially, and different pyrolytic carbon microstructures like regular smooth laminar tissue and isotropic smooth laminar tissue, coarse laminar tissue, the main contents include:(1) Based on Lattice Boltzmann method, for carbon fiber composite insulation structures, establish the heat conduction model, compile the calculation procedure of conducting and radiation using Fortran language and verify its reliability;(2) Calculate anisotropic heat-conducting performance of five structures between 273 K to 1273 K, analyze the effect of temperature, thickness, weave structure and microstructure of pyrolytic carbon have on its heat-conducting performance;(3) Calculate the equivalent heat transfer performance parameter of five structures under the coupled thermal radiation heat transfer, analyze the effect of temperature have on heat radiation, and compare the impact of heat radiation have on the heat-conducting performance of three different knitting structures and three different pyrolytic carbon microstructures of carbon fiber composite materials respectively.The study found that the temperature, the thickness and the woven structure of the carbon fiber composite materials all have a significant influence on the heat-conducting performance. Considering the equivalent heat transfer performance under radiation, they have little different with the same performance under pure thermal at low temperatures, however at the high temperatures more than 600 K, equivalent heat transfer performance higher than the same performance under pure thermal, providing design reference for the engineering application.