Development of a material response model for non-charring ablative materials and twodimensional/axisymmetric geometries is presented. This model is loosely coupled to a computational fluid dynamics code as a boundary condition subroutine to allow for prediction of the fluid/surface interactions that occur for an ablating material in hypersonic flow. This coupled solution technique is applied to the case of the IRV-2 vehicle and axisymmetric material response results are compared with a similar coupling procedure that uses a one-dimensional material response code. The effect of multidimensional material response appears to have little impact on the flow field for this case, but the in-depth temperature profiles of the IRV-2 vehicle are considerably different when comparing the axisymmetric and one-dimensional results.

Hypersonic flowfield and radiation analyses are performed before and after flight to study the physical conditions experienced by the automated transfer vehicle Jules Verne during reentry before breakup. Results are compared to those obtained with a miniature Echelle spectrograph operated from an airborne platform, measuring the flux density of atomic line emissions from oxygen and nitrogen, as well as many metals. Molecular emissions from CN and AlO are also detected. The vehicle lost its solar panels at 86 km and first broke up at 75 km. The main cargo cabin held together until 68 km. Postflight analyses focus on altitudes of 86, 75, and 68 km. A first analysis includes only air species, correctly predicting the observed oxygen and nitrogen atomic line intensities. N 2 band emission is systematically overestimated by at least a factor of 20, indicating a need for revision of the radiation model for this system. A second analysis includes blowing of metals (aluminum, sodium, potassium, and magnesium) from the vehicle surface. The blowing rates are inferred by requiring the computed and measured emissions to match. Magnesium and aluminum originate from ablation of structural elements, while sodium and potassium may have originated as impurities in paint.

For the purpose of predicting the environment encountered by hypersonic, ablating vehicles employing non-charring thermal protection systems, the coupling of a Navier-Stokes solver to both a material response code and finite-rate surface chemistry code is described. The Navier-Stokes solver used in this study is LeMANS, a three-dimensional computational fluid dynamics code used to simulate hypersonic flow fields including gasphase nonequilibrium thermochemistry. The material response solver used in this study is MOPAR, an implementation of the one-dimensional control-volume finite-element method for modeling heat conduction and pyrolysis gas behavior. The finite-rate surface chemistry code used in this study is a generalized framework that allows for any number of several types of surface reactions, such as adsorption/desorption, Eley-Rideal recombination, Langmuir-Hinshelwood recombination, oxidation/reduction, and sublimation/condensation to be considered. The test case used in this study is the nosetip of the IRV-2 vehicle, which employed a thermal protection system composed of non-charring carbon. A detailed discussion is given of the strategies used to couple the flow field solver, the surface chemistry solver, and the material response solver. The results produced using two finite-rate surface chemistry models are compared to previous results produced using the assumption of chemical equilibrium at the surface of the vehicle for a number of trajectory points of the IRV-2 vehicle.

The Method of Manufactured Solutions is used to perform order of accuracy code verification tests on some features of a hypersonic computational fluid dynamics (CFD) code and a material response code. The CFD verification tests include results for a two species gas mixture in thermal nonequilibrium, and the material response results are for an anisotropic material. After verifying the two codes separately, a verification test is performed with the codes loosely coupled so that the material response code provides updated boundary conditions to the CFD code. In the cases tested, the observed order of accuracy of the CFD code is less than the theoretical order. The tests of the material response code, however, show the expected order of accuracy.