GALCIT Colloquium

High-temperature gas-material interactions are critical processes in the development of hypersonic flight systems for space exploration and national defense. To be safe and effective throughout the extreme conditions of re-entry, designs must anticipate and be robust to changes in the aerodynamic shape and surface roughness due to ablation and oxidation.  Hand-in-hand with the development of computational capabilities has been a need for data to both validate models and identify key physical mechanisms. 

This talk will focus on multi-scale experiments on carbon fibers, the backbone of thermal protection materials for hypersonic flight. We will discuss how X-ray imaging at high resolution has become an invaluable tool to understand and quantify the response of porous materials subjected to extreme conditions. The core of the talk will focus on novel synchrotron light source experiments on carbon fibers where the ablation phenomenon is resolved in 4D, at high temperature, using real-time X-ray micro-tomography. From the high spatial and temporal resolution scans we were able resolve asymptotic regimes in carbon oxidation occurring at different flight conditions, from reaction-limited to the diffusion-limited regime. These data constitute the basis for predictive modeling tools for carbon ablation and high speed vehicle design.