Collisional-radiative and macroscopic models for the thermochemical relaxation of non-equilibrium hypersonic flows
type: Dataset
description: The thermo-chemical relaxation of nitrogen hypersonic flows behind strong shocks and in nozzle expansions is investigated with 1D flow simulations and detailed vibrational kinetics. This work aims at deriving from detailed vibrational models accurate reduced models easy to implement in multidimensional reentry flow codes. First, nonequilibrium couplings between vibrational excitation, dissociation and recombination reactions are considered. Vibrational kinetics is described using accurate vibrational state-to-state rate constant databases of the literature completed with the forced harmonic oscillator model. The key role of multiquanta vibration-translation processes on the relaxation of the vibrational distribution function and the dissociation/recombination processes is put forward behind shocks and in nozzles. The vibrational distributions, which deviate strongly from equilibrium for nozzle expansions, are driven by vibration-translation processes and dissociation/recombination processes. A macroscopic model using groups of vibrational levels is developed to derive consistently the chemical and vibrational energy source terms from the vibrational state-to-state database.This model successfully reproduces the thermal, chemical and vibrational distribution function dynamics predicted by the state-to-state model with one group of levels behind a shock wave, and with three groups of levels in nozzle expansions. In a second step, the detailed vibrational model is extended to ionized nitrogen flows, including in particular a detailed modeling of the resonant electronvibration processes. Behind shocks, these processes control the rate of ionization by feeding energy to the electrons, up until the time when the elastic electron-ion exchanges takes over. It is shown that the widely used assumption of equilibrium between the electron and vibration temperatures predicts a too fast relaxation behind shock waves. In nozzle expansions, it is shown that for low electron concent…
identifier: NNT: 2013ECAP0073
issued: 2026-05-05T14:50:50.162026
language: en
modified: 2026-05-05T14:50:50.162030
contact point: Organization
  fn: CCSD
keyword: cinetique-des-vibrations
keyword: collisional-radiative-models
keyword: ecoulements-hypersoniques
keyword: hypersonic-flows
keyword: infoeu-reposemanticsdoctoralthesis
keyword: modeles-collisionnels-radiatifs
keyword: spiotherengineering-sciences-physicsother
keyword: theses
keyword: vibrational-kinetics
landing page: https://theses.hal.science/tel-00978518

Collisional-radiative and macroscopic models for the thermochemical relaxation of non-equilibrium hypersonic flows
type: Distribution
format: HTML
issued: 2026-05-05T14:50:50.164543
modified: 2026-05-05T14:50:50.152550
access URL: https://theses.hal.science/tel-00978518

test_moissonnage_selune
type: Agent