Estimation of temperature-dependent thermal conductivity and specific heat capacity for charring ablators

Abstract

The accurate assessment of thermal properties is crucial for charring materials simulation and design. In this work, a new inversion method for estimating temperature-dependent thermal conductivity and specific heat capacity from temperature data is presented for charring ablators. Firstly, a one-dimensional thermal response model with surface recession is developed to simulate the thermal behavior of charring ablator. Then based on the developed model, sensitivity analysis is conducted to investigate the correlation between thermal parameters and temperature for determining inversion sequence and find that virgin thermal conductivity has the biggest influence on temperature which should be estimated at first. Finally, the temperature-dependent thermal conductivities and specific heat capacities are obtained by the inversion method from temperature data. The inversion values from simulation temperature data coincide with the reference values, which the average inversion error of thermal conductivities is 4.3% and the average inversion error of specific heat capacities is 3.1%. And the calculated thermal response temperature employing the inversion thermal properties shows a good agreement with the arc jet test data, which the average error is 8.5%. This inversion method can accurately determine unknown temperature-dependent thermal properties such as thermal conductivity and specific heat capacity, which provides an insight into the analysis and design of thermal protection materials for spacecraft.