Consistent multi-internal-temperatures models for nonequilibrium nozzle flows

A vibrational collisional model based on the database of the University of Bari is used to investigate nonequilibrium phenomena in nitrogen nozzle flows. For the cases studied, the vibrational distribution in the divergent section appeared to significantly deviate from a Boltzmann distribution. Multiquanta Vibration-Translation processes are shown to have a major influence on the recombination of the flow and on the shape of the vibrational distribution along the nozzle axis. Based on these results, a reduced model is derived with n groups of vibrational levels with their own internal temperatures to model the shape of the vibrational distribution. In this model, energy and chemistry source terms are calculated self-consistently from the rate coefficients of the vibrational database. For the studied nozzle flows, a good agreement is observed between the results of the vibrational collisional model with 68 levels and those of the reduced model with only 3 groups of levels. (C) 2013 Elsevier B. V. All rights reserved.