Three-Temperature Thermochemical Nonequilibrium Model with Application to Slender-Body Wakes

Abstract

Hypersonic fluid dynamic simulations commonly model thermochemical nonequilibrium processes with the two-temperature model, which consists of a translational–rotational and vibrational–electronic–electron temperature. However, constricting the free-electron energy, by grouping it with the vibrational, the two-temperature model does not model certain nonequilibrium phenomena, which decreases the fidelity of the solution. A three-temperature model, consisting of a translational–rotational, vibrational, and electron–electronic temperature, increases the degrees of freedom of the simulation, permitting the electron temperature to be independent, and thus captures more nonequilibrium physics than the two-temperature model. Such a three-temperature model was implemented within a computational-fluid-dynamics framework for the simulation of hypersonic flows, with particular attention paid to wake flowfields. Validation was completed against the RAM C-II flight test data, and an assessment of the three-temperature model’s performance within the wake was completed. Finally, a study characterizing the wake behind a generic, slender cone geometry was completed, in which the nonequilibrium processes were shown to extend a significant distance into the wake.