TY - JOUR

T1 - Reflected shock waves in air components and their mixtures: Validation of theoretical models

AU - Kravchenko, Denis

AU - Kunova, Olga

AU - Kustova, Elena

AU - Melnik, Maksim

PY - 2024/5/1

Y1 - 2024/5/1

N2 - Nonequilibrium flows of air components behind reflected shock waves are systematically studied on the basis of several theoretical models for the rate coefficients of fully coupled vibrational energy exchanges and chemical reactions. Numerical simulations are performed in the frame of the state-to-state approach under initial conditions corresponding to recent shock-tube experiments in mixtures O2/Ar, NO/Ar, NO/N2/Ar. The model takes into account partial vibrational relaxation between the incident and reflected shock waves, state-resolved dissociation, recombination, exchange reactions with formation of NO in the vibrationally excited states, as well as vibrational–vibrational and vibrational–translational energy transitions. It is shown that for oxygen, relaxation between the incident and reflected shocks is not frozen, and taking it into account in the most test cases considerably improves the agreement of calculated and experimentally measured pressure. For NO-containing mixtures, the effect of intermediate relaxation is weaker. Average deviation of the number density of molecular species with respect to the experimental one is analyzed for several hundreds of numerical simulations; on the basis of these estimates, recommendations are given for the best choice of model parameters. These recommendations can be used for modeling high-temperature flows, in particular, under reentry conditions.

AB - Nonequilibrium flows of air components behind reflected shock waves are systematically studied on the basis of several theoretical models for the rate coefficients of fully coupled vibrational energy exchanges and chemical reactions. Numerical simulations are performed in the frame of the state-to-state approach under initial conditions corresponding to recent shock-tube experiments in mixtures O2/Ar, NO/Ar, NO/N2/Ar. The model takes into account partial vibrational relaxation between the incident and reflected shock waves, state-resolved dissociation, recombination, exchange reactions with formation of NO in the vibrationally excited states, as well as vibrational–vibrational and vibrational–translational energy transitions. It is shown that for oxygen, relaxation between the incident and reflected shocks is not frozen, and taking it into account in the most test cases considerably improves the agreement of calculated and experimentally measured pressure. For NO-containing mixtures, the effect of intermediate relaxation is weaker. Average deviation of the number density of molecular species with respect to the experimental one is analyzed for several hundreds of numerical simulations; on the basis of these estimates, recommendations are given for the best choice of model parameters. These recommendations can be used for modeling high-temperature flows, in particular, under reentry conditions.

KW - High-temperature flow

KW - Model validation

KW - Reflected shock wave

KW - State-to-state kinetics

KW - Vibrational-chemical coupling

UR - https://www.mendeley.com/catalogue/bcfd221b-787f-3344-a0d8-a7bc3b6c473c/

U2 - 10.1016/j.actaastro.2024.02.011

DO - 10.1016/j.actaastro.2024.02.011

M3 - Article

VL - 218

SP - 47

EP - 58

JO - Acta Astronautica

JF - Acta Astronautica

SN - 0094-5765

ER -