Reduced Heat Flux Through Preferential Surface Reactions Leading to Vibrationally and Electronically Excited Product States
Technical Report,30 Sep 2012,30 Nov 2015
University of Minnesota Minneapolis United States
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Instead of characterizing a hypersonic flight environment and then selecting an appropriate thermal protection system TPS that can survive the environment, it would be a significant technological step forward if the TPS could be engineered to alter the hypersonic flight environment itself i.e.the boundary layer. A critical aspect of such a strategy is control over energy deposition pathways during catalytic recombination of dissociated air species on TPS surfaces. Experiments with laser-based diagnostics were used to simultaneously measure the loss of oxygen atoms and the production of oxygen molecules in the ground and electronically excited states as a partially dissociated oxygen flow interacts with a silica surface. Flow models were constructed and numerical calculations were performed to interpret the experimental data. New computational chemistry approaches, capable of modeling nonadiabatic oxygen interactions electronically excited interactions with surface defects, were developed.Through such computational chemistry modeling we determined precisely how and why such excited-state molecules are produced, by determining the specific silica defects and reaction pathways that are responsible.