Abstract: The thermal properties of high-alumina fibrous insulation which filled in metallic thermal protection system were investigated. The effective thermal conductivities of the fibrous insulation were measured under an atmospheric pressure from 10-2 to 105 Pa. In addition, the changes of the specific heat and Rosseland mean extinction coefficient were experimentally determined under various surrounding temperatures up to 973 K. The spectral extinction coefficients were obtained from transmittance data in the wavelength range of 2.5– 25 μm using Beer’s law. Rosseland mean extinction coefficients as a function of temperature were calculated based on spectral extinction coefficients at various temperatures. The results show that thermal conductivities of the sample increase with increasing temperature and pressure. Specific heat increases as temperature increases, which shows that the capacity of heat absorption increases gradually with temperature. Rosseland mean extinction coefficients of the sample decrease firstly and then increase with increasing the temperature.

Key words: Effective thermal conductivity, Extinction coefficient, Transmittance, Thermal physical properties