• Dr. Noel Clemens
  • The University of Texas at Austin
  • Location: 112 Robeson Hall
  • Time: 4:00 p.m.
  • Faculty Host: Dr. Lin Ma

Ablation remains a topic of current interest in the aerospace community owing to the need to develop thermal protection systems for spacecraft that undergo entry into planetary atmospheres. Ablation is a complex multi-physics process that involves high-temperature thermochemistry, radiation, gas-surface interactions, turbulent transport, mechanical erosion, etc., all of which combine to make it quite a challenging process to study. A particularly important physical process that remains very difficult to model is the transport of ablation products in high-speed turbulent boundary layers that develop in the presence of surface roughness and strong pressure-gradients. The study of scalar transport is enabled by a new technique that has been developed at The University of Texas at Austin, which uses planar laser-induced fluorescence of the gas-phase products resulting from a sublimating ablator (naphthalene) exposed to a high-speed flow. In this presentation details of the technique will be discussed including measurements of the photo-physical properties of naphthalene such as the temperature variation of the absorption and quenching cross-sections. Such data are necessary to enable the use of the technique for quantitative measurements of the scalar concentration. Results will be shown for the application of the technique to study scalar dispersion in a Mach 5 boundary layer and to visualize ablation on a subscale space capsule model.