Abstract
To protect a spacecraft entering planetary atmosphere from severe aerodynamic heating, an appropriate thermal protection system must be designed by a sophisticated simulator which provides a precise prediction of heat load at the vehicle surface. In a hypersonic speed, highly nonequilibrium flow is formed at the front of the vehicle, and thus thermochemical modeling is crucial for predicting the aerodynamic heating. Although some models have been proposed by comparing flight data so far, we should know the uncertainty in the models for obtaining a high fidelity prediction of the hypersonic flow. In this study, we have investigated on uncertainty quantification and sensitivity analysis for the present and advanced thermochemical models. Since computational costs for the uncertainty quantification using conventional Monte-Carlo approach and full Navier-Stokes code are considerably expensive with number of uncertainty variables, we have performed the uncertainty quantification for the thermochemical models via non-intrusive polynomial chaos approach coupling with viscous shock-layer code, which works with much lower computational costs. In the analysis on O2 and N2 dissociations of the reentry flowfield, the stand-off distance of the detached shock wave is deviated by the uncertainty of the reaction rate constants especially for the nitrogen dissociation.
