Uncertainty Analysis of Laminar Aeroheating Predictions for Mars Entries

Abstract

A Monte Carlo sensitivity and uncertainty analysis is performed for a laminar convective heating prediction in a moderate Mars atmospheric entry condition using a nonequilibrium reacting Navier-Stokes computational fluid dynamics code. The objectives are to isolate the rate limiting mechanisms and identify the chief sources of aeroheating uncertainty. A flux-based wall catalysis formulation is developed and used to define four different catalytic regimes that are then individually analyzed at three different trajectory points. A total of 130 input parameters are statistically varied to short list a handful of parameters that essentially control the heat flux prediction. The uncertainties in these key input parameters are estimated, and a full Monte Carlo uncertainty analysis is performed. The results obtained provide the quantitative contribution of uncertainties in key modeling parameters, such as collision integrals, wall catalysis, and reaction rates to the final heat flux uncertainty. It is found that in high and low catalytic regimes, the collision integrals (which govern the transport properties of the mixture) contribute a large portion of the uncertainty, whereas in the moderately catalytic regime the catalytic properties of the surface contribute almost all of the uncertainty.