Radiative Heating Uncertainty for Hyperbolic Earth Entry, Part 1: Flight Simulation Modeling and Uncertainty

This paper investigates the shock-layer radiative heating uncertainty for hyperbolic Earth entry, with the main focus being a Mars return. A baseline simulation approach involving the Laura Navier-Stokes code with coupled ablation and radiation is presented, with the Hara radiation code being used for the radiation predictions. Flight cases representative of peak heating Mars or asteroid return are defined, and the strong influence of coupled ablation and radiation on their aerothermodynamic environments are shown. Structural uncertainties inherent in the baseline simulations are identified, with turbulence modeling, precursor absorption, grid convergence, and radiation transport uncertainties combining for a +34+34 and -24%-24% structural uncertainty on the radiative heating. A parametric uncertainty analysis, which assumes interval uncertainties, is presented. This analysis accounts for uncertainties in the radiation models, as well as heat of formation uncertainties in the flowfield model. Discussions and references are provided to support the uncertainty range chosen for each parameter. A parametric uncertainty of +47+47 and -28%-28% is computed for the stagnation-point radiative heating for the 15km/s15km/s Mars-return case. A breakdown of the largest individual uncertainty contributors is presented, which includes C3C3 Swings cross section, photoionization edge shift, and Opacity Project atomic lines. Combining the structural and parametric uncertainty components results in a total uncertainty of +81+81 and -52%-52% for the Mars-return case. [PUBLICATION ABSTRACT]