A toolkit for characterizing uncertainties in hypersonic flow-induced ablation

A one-dimensional, quasi-steady ablation model with finite rate surface chemistry and frozen equilibrium pyrolysis gases is developed and discussed. This material response model is then coupled to a film-transfer boundary layer model to enable the computation of heat and mass transfer to and from the ablating surface. A shock model is outlined, as well, and all three components are then coupled together to form a stand-alone ablation code.

The coupled models in the code are validated with respect to arcjet experiments, and comparisons are drawn between the ablation code and the unsteady ablation code Chaleur, as well as other computations for a graphite ablator in an arcjet. The coupled code is found to compare very well to both the experimental results and the other calculations. It is also found to have unique computational capabilities due to the use of finite-rate surface chemistry.

Finally, uncertainty propagation using the quadrature method of moments (QMOM) is discussed. The method is applied to a number of simplified sample problems, for both univariate and multivariate scenarios. QMOM is then used to compute the uncertainty in an application of the coupled ablation code using a graphite ablator. The results of this study are discussed, and conclusions about the utility of the method as well as the properties of the ablation code are drawn.