Understanding gas–phase chemical kinetics is important for modeling hypersonic flows. This paper discusses quasiclassical trajectory analysis, in which gas–phase interactions are simulated using ab initio quantum chemistry data. N2 N2, N2 N, and N2 O2 collisions are studied for conditions at thermal equilibrium and nonequilibrium. The nitrogen dissociation rate with all collision partners is found to be similar for a given thermal environment: the largest deviation is 50% at thermal nonequilibrium, and at equilibrium the N2 N2 and N2 N rates are within 15% of each other. The vibrational energy decrease due to nitrogen dissociation, a necessary input to computational fluid dynamics, also behaves similarly for all collision partners and strongly depends on the degree of thermal nonequilibrium. Using data for nitrogen dissociation and oxygen dissociation with partner N2, the effect of each reactant state on dissociation is quantified. The effect of the collision partner’s internal energy on simple dissociation is found to be small and likely negligible. Finally, the effect of vibrational energy on simple dissociation is found to be stronger than the effect of rotational energy. These rigorous statistical analyses enable the development of physics-based models for computational fluid dynamics.
Bibliographical noteFunding Information:
This work was sponsored by the Air Force Office of Scientific Research under grant numbers FA9550-16-1-0161 and FA9550-17-0250. J. D. Bender was supported in this work by the U.S. Department of Energy Computational Science Graduate Fellowship under grant number DE-FG02-97ER25308. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the funding agencies or the U.S. Government.
© 2018 by Ross S. Chaudhry.