Unsteady behavior and thermochemical non equilibrium effects in hypersonic double-wedge flows

Ninni, Davide; Bonelli, Francesco; Colonna, Gianpiero; Pascazio, G.

doi:10.1016/j.actaastro.2021.10.040

Cited by 25 publications

(3 citation statements)

References 31 publications

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“…However, accurately characterizing the degree of thermochemical excitation in the experimental freestream is critical for the correct interpretation of experimental data for blunt and slender body studies as well as scramjet studies, and this concept is well documented in literature [4,[14][15][16][17][18][19]. High fidelity state-to-state (StS) thermochemical nonequilibrium models do exist, though their applications have mainly focused on shock waves and converging-diverging nozzle flows where excellent work has been done [20][21][22][23][24][25][26]. Though, as mentioned earlier, converging-diverging nozzle flows are not relevant to the expansion tunnel.…”

Section: Fig 1 the Expansion Tunnel And Corresponding X-t Diagrammentioning

confidence: 99%

State-Specific Study of Air in the Expansion Tunnel Nozzle and Test Section

Hao

Wen

2022

AIAA Journal

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Thermochemical nonequilibrium in expansion tunnel nozzles is investigated numerically using a state-to-state description in one-dimension for representative air conditions. Limiting the multi-quantum jumps of VVT transitions to 3 in both N2 and O2 can accurately simulate the nonequilibrium nozzle flow. The reduction of VVT transitions to VT transitions works well. State-to-state modelling of an actual expansion tunnel nozzle condition yielded agreement with the measured static pressure. A study on the influence of different thermochemical excitation in the freestream at the test section shows that the post-shock radiation emissions can differ by more than 50 %. However, the non-Boltzmann distributions in the freestream has no influence. An evaluation of the discrepancy between the twotemperature and state-to-state models shows that the former generally predicts a faster thermochemical relaxation. Furthermore, the state-to-state results indicate that, in general, the molecular species all have a different vibrational temperature.

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Section: Fig 1 the Expansion Tunnel And Corresponding X-t Diagrammentioning

confidence: 99%

State-Specific Study of Air in the Expansion Tunnel Nozzle and Test Section

Hao

Wen

2022

AIAA Journal

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“…The surface heat flux of the double wedge calculated by 2-T models deviates significantly from experimental results. 10,11 In recent years, with the abundance of computational resources, the state-to-state (STS) method has received wide interest. The STS method treats molecules at different states as different species to participate in the calculation so that the energy state distribution in the relaxation process can be accurately obtained.…”

Section: Introductionmentioning

confidence: 99%

“…The surface heat flux of the double wedge calculated by 2-T models deviates significantly from experimental results. 10,11…”

Section: Introductionmentioning

confidence: 99%

Vibrational non-Boltzmann effects on the dissociation rate of oxygen

Xiong¹,

Han²,

Cao³

2023

Phys. Chem. Chem. Phys.

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Extension of the normal shock wave relations for calorically imperfect gases

Civrais,

White,

Steijl

2023

Shock Waves

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An extension to the normal shock relations for a thermally perfect, calorically imperfect gas, modelling the vibrational excitation with an anharmonic oscillator model and including the influence of electronic modes, is derived and studied. Such additional considerations constitute an extension to the work achieved in the past, which modelled the caloric imperfections with a harmonic oscillator for vibrational energy and did not consider the effect of electronic energy. Additionally, the newly derived expressions provide physical insights into the limitations of experimentation for replicating flight conditions, which is demonstrated through providing solutions at different upstream temperatures. The results are compared with direct simulation Monte Carlo simulations for nitrogen and air, with the extent of the caloric imperfection of the gas showing excellent agreement. For low upstream temperatures, the extended relations are found to be in good agreement with the original normal shock wave expressions, but the results diverge for higher upstream temperatures that would be more representative of real flows. The results show that the new expressions depart from ideal gas theory for Mach numbers in excess of 4.9 at wind-tunnel conditions and for any Mach number above 3.0 at flight conditions. It is also shown that the traditional harmonic oscillator model and the anharmonic oscillator model begin to diverge at Mach number 3.0 for molecular oxygen gas and at Mach number 5.0 for an air mixture at flight conditions.

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Unsteady behavior and thermochemical non equilibrium effects in hypersonic double-wedge flows

Cited by 25 publications

References 31 publications

State-Specific Study of Air in the Expansion Tunnel Nozzle and Test Section

State-Specific Study of Air in the Expansion Tunnel Nozzle and Test Section

Vibrational non-Boltzmann effects on the dissociation rate of oxygen

Extension of the normal shock wave relations for calorically imperfect gases

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