Impact of state-specific flowfield modeling on atomic nitrogen radiation

Christopher O. Johnston and Marco Panesi
Phys. Rev. Fluids 3, 013402 – Published 18 January 2018

Abstract

A hypersonic flowfield model that treats electronic levels of the dominant afterbody radiator N as individual species is presented. This model allows electron-ion recombination rate and two-temperature modeling improvements, the latter which are shown to decrease afterbody radiative heating by up to 30%. This decrease is primarily due to the addition of the electron-impact excitation energy-exchange term to the energy equation governing the vibrational-electronic electron temperature. This model also allows the validity of the often applied quasi-steady-state (QSS) approximation to be assessed. The QSS approximation is shown to fail throughout most of the afterbody region for lower electronic states, although this impacts the radiative intensity reaching the surface by less than 15%. By computing the electronic-state populations of N within the flowfield solver, instead of through the QSS approximation in the radiation solver, the coupling of nonlocal radiative transition rates to the species continuity equations becomes feasible. Implementation of this higher-fidelity level of coupling between the flowfield and radiation solvers is shown to increase the afterbody radiation by up to 50% relative to the conventional model.

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  • Received 11 October 2017

DOI:https://doi.org/10.1103/PhysRevFluids.3.013402

Published by the American Physical Society

Physics Subject Headings (PhySH)

Plasma PhysicsFluid Dynamics

Authors & Affiliations

Christopher O. Johnston*

  • NASA Langley Research Center, Hampton, Virginia 23681, USA

Marco Panesi

  • Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA

  • *christopher.o.johnston@nasa.gov

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Vol. 3, Iss. 1 — January 2018

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