Boltzmann rovibrational collisional coarse-grained model for internal energy excitation and dissociation in hypersonic flows

A. Munafò, M. Panesi, and T. E. Magin
Phys. Rev. E 89, 023001 – Published 5 February 2014

Abstract

A Boltzmann rovibrational collisional coarse-grained model is proposed to reduce a detailed kinetic mechanism database developed at NASA Ames Research Center for internal energy transfer and dissociation in N2N interactions. The coarse-grained model is constructed by lumping the rovibrational energy levels of the N2 molecule into energy bins. The population of the levels within each bin is assumed to follow a Boltzmann distribution at the local translational temperature. Excitation and dissociation rate coefficients for the energy bins are obtained by averaging the elementary rate coefficients. The energy bins are treated as separate species, thus allowing for non-Boltzmann distributions of their populations. The proposed coarse-grained model is applied to the study of nonequilibrium flows behind normal shock waves and within converging-diverging nozzles. In both cases, the flow is assumed inviscid and steady. Computational results are compared with those obtained by direct solution of the master equation for the rovibrational collisional model and a more conventional multitemperature model. It is found that the proposed coarse-grained model is able to accurately resolve the nonequilibrium dynamics of internal energy excitation and dissociation-recombination processes with only 20 energy bins. Furthermore, the proposed coarse-grained model provides a superior description of the nonequilibrium phenomena occurring in shock heated and nozzle flows when compared with the conventional multitemperature models.

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  • Received 21 August 2013

DOI:https://doi.org/10.1103/PhysRevE.89.023001

©2014 American Physical Society

Authors & Affiliations

A. Munafò1,*, M. Panesi2,†, and T. E. Magin1,‡

  • 1Aeronautics and Aerospace Department, von Karman Institute for Fluid Dynamics, Chaussée de Waterloo 72, 1640 Rhode-Saint-Genèse, Belgium
  • 2Department of Aerospace Engineering, Talbot Laboratory, University of Illinois at Urbana-Champaign, 104 South Wright Street, Urbana, Illinois 61801, USA

  • *munafo@vki.ac.be
  • Corresponding author: mpanesi@illinois.edu
  • magin@vki.ac.be

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Issue

Vol. 89, Iss. 2 — February 2014

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