Loosely Coupled Simulation for Two-Dimensional Ablation and Shape Change

The central focus of this study is to demonstrate that time-accurate solutions for multidimensional ablation and shape change of thermal protection system materials may be obtained by loose coupling of a high-fidelity flow solver with a material thermal response code. In this study, the flow code solves the nonequilibrium Navier-Stokes equations using the data-parallel line-relaxation (DPLR) method. The material response code is the latest version of the Two-dimensional Implicit Thermal Response and Ablation Program (TITAN). In TITAN, the governing equations, which include a three-component decomposition model and a surface energy balance with thermo-chemical ablation, are solved with a robust moving-grid scheme to predict the shape change caused by surface recession. Coupling between the material response and flow codes is required for many multidimensional ablation simulations, because the magnitude and distribution of the surface heat flux are very sensitive to shape change. This paper demonstrates the application of the TITAN-DPLR system to problems with large-scale recession and shape change. Ablation and thermal response simulations are presented for iso-q and flat-faced arc-jet test models and also for a wedge with a cylindrical leading edge exposed to hypersonic flow at various angles of attack.