Semi-Empirical 1D Material Response Modeling Using Inverse Methods

Experiments were conducted using both the Interaction Heating Facility (IHF) and Aerodynamic Heating Facility (AHF), two hypersonic arc-jet facilities at NASA Ames Research Center. These tests were performed to understand the material response of ablative thermal protection system materials by exposing them to high-enthalpy flows. Using in-depth thermocouple measurements from a graphite test article, test conditions were determined using NASA’s one-dimensional inverse heat conduction model FIAT-Opt. A least squares fit function was found to recreate these boundary conditions as a reproducible case. Comparisons were also made with results from the one-dimensional model FIAT using CFD-derived facility target conditions. The two cases were additionally compared and validated using thermocouple measurements from another material, as well as calorimetry measurements during the same test. Additional validation against data other test series confirmed the applicability of this approach to modeling cases in other facilities.