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Fluid Mechanics Seminar
Analysis of meteoroid ablation based on plasma wind-tunnel experiments, surface characterization, and numerical simulations
Thierry Magin
Professor
Aerodynamics, VKI
Thursday, February 14, 2019, 3:30 pm
ASE 2.202

Meteoroids largely disintegrate during their entry in the atmosphere, contributing significantly to the input of cosmic material to Earth. Yet, their atmospheric entry is not well understood. Experimental studies on meteoroid material degradation in high-enthalpy facilities are scarce and when the material is recovered after testing, it rarely provides sufficient quantitative data for the validation of simulation tools. In this work, we investigate the thermo-chemical degradation mechanism of a meteorite in a high-enthalpy ground facility able to reproduce atmospheric entry conditions. A testing methodology involving measurement techniques previously used for the characterization of thermal protection systems for spacecraft is adapted for the investigation of ablation of alkali basalt (employed here as meteorite analogue) and ordinary chondrite samples. Both materials are exposed to a cold-wall stagnation point heat flux of 1.2 MW/m2. Numerous local pockets that formed on the surface of the samples by the emergence of gas bubbles revealed the frothing phenomenon characteristic during material degradation. Time resolved optical emission spectroscopy data of ablated species allowed us to identify the main radiating atoms and ions of potassium, calcium, magnesium, and iron. Surface temperature measurements provided maximum values of 2280K for the basalt and 2360K for the  chondrite samples. We also developed a material response model by solving the heat conduction equation and  accounting for evaporation and oxidation reaction processes in a 1D Cartesian domain. The simulation results are in good agreement with the data collected during the experiments, highlighting the importance of iron oxidation to the material degradation.

Contact  Dr. David Goldstein david@ices.utexas.edu or (512) 471-4187

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