Fundamental Studies of Vibrationally Resolved Air Kinetics in the Vicinity of a Partially Catalytic Surface
Abstract
Catalytic reactions on the surface of thermal protection systems have a pronounced effect on the near-surface flow composition and can account for a large portion of the total heat flux. For example, two-thirds of the total heat flux to a ceramic leading edge at Mach 15 and at 35 km altitude can be due to chemical reactions occurring on the surface. Characterization of a gas surface interaction is thus an important component in vehicle analysis and design. Certain oxides formed on protective surfaces or used as protective coatings, such as SiO2, are partially catalytic- they enable surface recombination reactions with incomplete thermal accommodation of molecular products. These products may desorb from a surface in vibrationally and electronically excited states thus potentially changing the heat flux distribution as species deposit the energy downstream. The rate of thermochemical processes in the gas phase and composition near catalytic surfaces can also be altered in the presence of such non-thermal species. This is important to consider for the design of sharp leading edges and for the characterization of catalytic properties of materials in testing facilities. The non-thermal flux of molecular species leaving a surface presents a challenge for conventional multi-temperature models. This is due to their intrinsic assumption of a vibrational temperature established in the flow. The last decade showed remarkable progress in state-resolved aerothermochemistry models albeit proposed exclusively for the gas phase away from surfaces. These state-resolved models do not rely on a concept of internal temperatures, which makes them an ideal tool for the analysis of non-thermal reactions.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 29, 2024
- Source ID
- FA95502310274
Entities
People
- Daniil A Andrienko
Organizations
- Air Force Office of Scientific Research
- Regents of the University of Colorado
- United States Air Force