Evaluation of Finite-Rate Gas/Surface Interaction Models for Carbon-Based Ablator

Abstract

Two sets of finite-rate gas/surface interaction model between air and the carbon surface are studied. The first set is an engineering model with one-way chemical reactions, and the second set is a more detailed model with two-way chemical reactions. Each of these two proposed models intends to cover the carbon surface ablation conditions including the low-temperature rate-controlled oxidation, the midtemperature diffusion-controlled oxidation, and the high-temperature sublimation. The prediction of carbon surface recession is achieved by coupling a material thermal response code and a Navier–Stokes flow code. The material thermal response code used in this study is the Two-Dimensional Implicit Thermal-Response and Ablation Program, which predicts charring material thermal response and shape change on hypersonic space vehicles. The flow code solves the reacting full Navier–Stokes equations using the data parallel line relaxation method. Recession analyses of stagnation tests conducted in NASA Ames Research Center arc-jet facilities with heat fluxes ranging from 45 to are performed and compared with data for model validation. The ablating material used in these arc-jet tests is phenolic impregnated carbon ablator. Computational predictions of surface recession and shape change are in good agreement with measurement for arc-jet conditions.