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The effect of internal energy on chemical reaction rates as predicted by Bird's quantum-kinetic model

Gallis, Michail A.; Torczynski, J.R.

The effect of non-equilibrium internal energy excitation on the reaction rates predicted by Bird's Quantum-Kinetic (Q-K) model for dissociation and exchange reactions is analyzed. The effect of vibrational non-equilibrium is treated explicitly by the Q-K model. The effect of rotational non-equilibrium is introduced as a perturbation to the effect of vibrational non-equilibrium in chemical reactions. For dissociation reactions, a small but measurable improvement in the rates is observed. For exchange reactions, the change is negligible. These findings are in agreement with experimental observations and theoretical predictions. The results from one-dimensional stagnation-streamline and two-dimensional axi-symmetric DSMC code implementations of the original and modified Q-K models are compared for a typical re-entry flow. The influence of rotational non-equilibrium in promoting chemical reactions is seen to be small for this type of flow. © 2012 American Institute of Physics.