Two-dimensional implicit thermal response and ablation program for charring materials

The TITAN program for predicting charring material ablation and shape change of thermal protection materials is presented. The governing equations include energy conservation and a three-component decomposition model. The surface energy balance condition is solved with a moving grid to calculate the shape change due to surface recession. The governing equations are discretized with a finite volume approximation with a general body-fitted coordinate system. A time-accurate solution is achieved by an implicit time-marching technique with Gauss-Seidel line relaxation with alternating sweeps. Benchmark solutions are calculated and compared with available solutions to check code consistency and accuracy. For fully coupled solid-fluid simulation, this technique has been directly integrated with both a high-fidelity Navier-Stokes solver and an aerothermal flowfield engineering correlation code. Representative computations, including a slender hypersonic reentry vehicle and a flat-faced cylinder model in an arcjet test, are presented and discussed in detail.