Effects of spalled particles thermal degradation on a hypersonic flow field environment

Abstract

The presence of spalled particles might affect the flow field and the material, thereby influencing the aerodynamic heating rates of the thermal protection system. In order to study the impact of particles on the flowfield, a two-way coupling is performed between a Lagrangian particle trajectory model and a hypersonic aerothermodynamics flow solver. Time-accurate solutions are computed for argon and air flowfields. Single-particle and multiple-particle simulations are performed and results are studied. The studies in the argon environment indicated that the particles start sublimating soon after they cross the shock and keep sublimating during the remainder of their time in the flow. In the air environment, the particles start releasing carbon vapor soon after their ejection, and the magnitudes of different carbon products vary based on the particle’s location relative to the shock. Similar behavior is observed for multiple-particle simulations but with an increase in the amount of released carbon vapor that diffuses and convects over a larger area. A single-particle simulation is also run by adding additional gas phase reactions, and it is found that the production rate of certain carbon products (C1 and CN) increases. A parametric study is conducted based on parameters that affect the motion of the particles. The results of the comprehensive study show that the carbon vapor released by spalled particles tends to change the composition of the flow field, particularly the upstream region of the shock, which affects the heat flux incident on the test sample.