Simulation of TPS crack growth due to carbon oxidation using advanced grid morphing techniques

A carbon wall oxidation model coupled with CFD was employed to study the flow in the expanding crack channel caused by the oxidation of the channel carbon walls. A recessing 3D surface morphing procedure was developed and tested by comparison with arcjet experimental results. A multi-block structured adaptive meshing was used to model the computational domain changes due to the wall recession. Wall regression rates for reinforced carbon-carbon (RCC) samples, that were tested in a high enthalpy arcjet environment, were computationally obtained and used to assess the channel expansion rate and highly three dimensional shape change. The studied specimens were the RCC samples, modeling a portion of the Space Shuttle wing, that has been studied in ground-based arcjet tests¹ and the high velocity meteoroid impact holes subjected to the arcjet flow conditions that were presented in Ref. 2. The test geometry and flow conditions render the flow regime as transitional to continuum, therefore, a Navier-Stokes based gas dynamic approach with the temperature jump and velocity slip correction to the boundary conditions was used. The modeled mechanism for wall material loss was atomic oxygen reaction with bare carbon. The predicted channel growth and shape change was found to agree with arcjet observations. Local gas flow field results were found to affect the oxidation rate in a manner that cannot be predicted by previous mass loss correlations. The method holds promise for future modeling of materials gas-dynamic interactions for hypersonic flight.