Thermal protection system crack growth simulation using advanced grid morphing techniques

An extension of previous [Titov, E., Zhong, J., Levin, D., and Picetti, D., "Simulation of RCC Crack Growth Due to Carbon Oxidation in High-Temperature Gas Environments," Journal of Thermophysics and Heat Transfer, Vol. 23, No. 3, July-Sept 2009, pp. 489-501.] modeling of crack damage growth in reinforced carbon-carbon specimens is presented in this work. The specimens were studied in an arcjet and represented a portion of the space shuttle wing [Lewis, R., "Quick Look Report," Atmospheric Reentry Materials and Structures, 2004.] and a high-velocity meteoroid impact [Curry, D. M., Pham, V. T., Norman, I., and Chao, D. C, "Oxidation of Reinforced Carbon-Carbon Subjected to Hypervelocity Impact," NASA TP 2000-209760, March 2000.]. The test geometry and flow conditions rendered 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 the bare, exposed carbon surface. The purpose of this work is to improve the predictive modeling of crack growth damage assessment by developing procedures that use coupled, advanced topology-based surface and grid-meshing tools. A recessing three-dimensional surface morphing procedure was developed and tested by comparison with arcjet experimental results. A multiblock structured adaptive meshing was used to model the computational domain changes due to the wall recession. This approach made it possible to model full three-dimensional crack growth scenarios as well as to include the presence of realistic reinforced carbon-carbon material features such as delamination, both of which affect damage growth because they enable higher atomic oxygen penetration. Comparison with the arcjet data show that the inclusion of these two factors further improves the comparison between modeling and data. The predicted channel growth and shape change were found to agree with arcjet observations, and local gas flowfield 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.