AEM Department Head Search Seminar: Dr. Tom Schwartzentruber - Today @ 2:30
Erin Carter
Gas-Surface Interactions for Hypersonics and Near-Space
Materials used for hypersonic vehicles and low-orbiting satellites must withstand harsh environments. Hypersonic flight generates a shock-heated, partially dissociated gas. Reactive atomic oxygen and nitrogen drive chemical reactions on material surfaces resulting in ablation or complex oxide layer formation. In low earth orbit, the outer region of Earth’s atmosphere is comprised mainly of oxygen atoms. Satellite materials must withstand collisions with reactive oxygen atoms at orbital velocity (7-8 km/s). For near-space altitudes, the flow transitions from continuum to free-molecular and gas-surface scattering dominates lift and drag.
This presentation describes new gas-surface interaction models that can be used in rarefied or continuum flow solvers to simulate low orbit satellites and hypersonic vehicles. The models were developed using recent molecular beam experimental data. The first type of model uses molecular beam scattering data for mixtures of dissociated air species reacting with high temperature carbon materials. This data is used to construct a 20-reaction air-carbon ablation model for use in large-scale CFD simulations of hypersonic flows. The second type of model is based on beam-surface scattering data for orbital velocity oxygen atoms impacting various satellite materials, including near-specular scattering materials that have the potential for low drag and high lift/drag. Instead of relying on conventional assumptions of either fully diffuse or specular reflection, this new model will provide quantitative predictions of satellite aerodynamics in low earth orbit.
Bio: Dr. Schwartzentruber received his PhD from the University of Michigan in 2007 and joined the faculty at the University of Minnesota the same year. His expertise involves molecular simulation of nonequilibrium gases and gas-surface interactions. He specializes in particle simulation methods such as direct simulation Monte Carlo (DSMC) and molecular dynamics (MD). Schwartzentruber is also an expert in coupling these methods with each other and with continuum (CFD) methods to efficiently simulate practical engineering flows. Together with his research group, Schwartzentruber has published 82 journal articles, more than 110 full-length AIAA conference papers, and a textbook on Nonequilibrium Gas Dynamics and Molecular Simulation. He and his students have received four best paper awards from the AIAA and he is currently an Associate Fellow of the AIAA.
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