An experimental study of effective thermal conductivity of high temperature insulations

An experimental apparatus was designed and fabricated to measure the effective thermal conductivities and simulate the temperature and pressure history of reentry of a launch vehicle into a planetary atmosphere with a maximum temperature of 1600°C. An improved testing method was used to test the thermal conductivities of an alumina fibrous insulation at environmental pressures from 0.03 Pa to 10⁵ Pa with the average temperature of the sample increased to 864°C and its density being 128 kg/m³. A method based on temperature difference is used to compute the in-plane effective thermal conductivity, and the result shows that the in-plane thermal conductivity along the y axis is 1.47 times that along the x axis. The influences of temperature and pressure on the contribution of three heat transfer mechanisms to the effective thermal conductivities were compared.