Practical Navier-Stokes computation of flowfields with ablation products injection

CFD codes typically treat fluid/solid boundary conditions in a simplified manner such as constant prescribed temperature or heat flux with zero mass transfer. However, thermal protection materials strongly interact with the flow so that simple CFD surface boundary conditions cannot realistically be used for TPS design. In order to obtain a better estimation of the wall heat flux over an ablating surface, a two-dimensional axisymmetric full Navier-Stokes equation solver is used coupled with surface mass balance and an ablation model. The wall composition is computed basing on equilibrium reactions with the solid phase (graphite) and the species are not allowed to react with each other as they diffuse across the boundary layer. The effect of gas injection in the boundary layer is studied focusing the attention on the wall heat flux and its reduction due to the blowing effect. Flat plate tests are presented. Results are compared with the most commonly used blowing rate correction equations.