Transport coefficients for high temperature nonequilibrium air flows

Fertig, Markus; Dohr, A.; Fruehauf, H.-H.

doi:10.2514/6.1998-2937

Cited by 24 publications

(13 citation statements)

References 13 publications

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“…The collision cross sections are taken from a study by Gupta et al [13]. However, for e-N and e-O pairs, the model by Fertig et al [16,17] is used. The diffusion coefficients are expressed using Curtiss and Hirschfelder's formula [18].…”

Section: B Physical Modelsmentioning

confidence: 99%

Aerodynamic-Heating Analysis of Sample-Return Capsule in Future Trojan-Asteroid Exploration

Takahashi

Yamada

2018

Journal of Thermophysics and Heat Transfer

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In sample-return missions, the reentry velocity of a sample-return capsule is expected to be approximately 15 km∕s; however, the reentry velocity of the Hayabusa sample-return capsule was 11.8 km∕s. Strong aerodynamic heating caused by a high velocity can damage the capsule during reentry. To overcome this, two designs of highvelocity reentry capsules were proposed. In one design, a rigid flare was attached to decrease the ballistic coefficient by increasing the front projected area. In the other design, the conventional Hayabusa sample-return capsule was used with no modifications. In this study, the aerodynamic heating of the high-velocity reentry capsules and the Hayabusa sample-return capsule was analyzed using numerical simulations. Plasma flow in the shock layer at the front of the capsules and expansion flow in the wake region around the capsules were investigated. The profiles of convective and radiative heat fluxes on the surfaces of these capsules were predicted. The heat fluxes at the stagnation points predicted by the present numerical simulation were in good agreement with that of the empirical models. At the strongest aerodynamic-heating altitude, the total heat fluxes at the rear of the high-velocity reentry capsules and the Hayabusa sample-return capsule were approximately 2% of those in front of the capsules. Nomenclature A = area, m 2 a = model parameter B = blackbody function, W∕m 3 B C = ballistic coefficient C = mass fraction C d = drag coefficient D = effective diffusion coefficient, m 2 ∕s f = function h = enthalpy, J∕kg I = radiation intensity, W∕m 3 Kn GLL = gradient-length-local Knudsen number k = Boltzmann constant, J∕K M = molar mass, kg∕mol m = mass, kg N A = Avogadro constant, mol −1 n = normal direction coordinate, m q = heat flux, W∕m 2 R N = nose radius, m s = one-dimensional coordinate, m T = temperature, K u, V = velocity, m∕s γ = catalytic coefficient θ = angle, rad κ = absorption coefficient, m −1 λ = mean free path, m ρ = density, kg∕m 3 Ω = solid angle, sr Subscripts ele, e = electron i = chemical species rot, R = rotation stag = stagnation trs, T = translation vib, V = vibration w = wall λ = wavelength ∞ = freestream Superscripts conv = convection rad = radiation

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Section: B Physical Modelsmentioning

confidence: 99%

Aerodynamic-Heating Analysis of Sample-Return Capsule in Future Trojan-Asteroid Exploration

Takahashi

Yamada

2018

Journal of Thermophysics and Heat Transfer

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“…stagnation enthalpy, Pitot pressure and Mach number) have been derived using various Probe techniques 6,26) developed at IRS. Numerical data such as transport coefficients, dynamic viscosity and effective probe radii were calculated with the Upwind Relaxation Algorithm for Nonequilibrium flows of the University of Stuttgart (URANUS) 27) . Most physical properties of the candidate materials and gases were supported by the supplier or can be found in literature.…”

Section: Methodology For Determination Of Recombination Coefficientsmentioning

confidence: 99%

Catalysis of Metallic and Ceramic TPS-Materials

Herdrich

Fertig

2009

Trans. JSASS Space Tech. Japan

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A facility for the determination of total and spectral emission coefficients is described. Values of measured total emission coefficients of the different high temperature ceramics such as HfO2, Al2O3, Yt2O3 and the metals/alloys Tungsten, TZM and PM1000 in the temperature regime of 750-1800 K are given. The drastic influence of the oxidation state of PM1000 on the emissivity is discussed. Additionally, results of an investigation of the influence of surface roughness and surface topology on emissivity are presented. Therefore, three SSiC samples with root-mean-squared roughness surface roughness from Rq = 0.05 to Rq = 0.66 have been prepared using common finishing operations. The tests showed that the emissivity increased about 10 % with an increase of the surface roughness even in the regime where Rq values are in the same magnitude or much smaller than the maximum emitting wavelength. Knowledge on emissivity is a basis for the analysis of thermo-chemical behavior and related properties (i.e. recombination coefficients) as the two properties influence each other. In a second step a high enthalpy inductively heated plasma wind tunnel (PWK3) is described and a methodology to derive recombination coefficients is explained. Recombination coefficients for the above mentioned materials have been determined in pure oxygen plasma. The methodology for the determination of recombination coefficients of ceramic and metallic Thermal Protection System (TPS) materials in single species gases used at IRS and its latest improvements are presented. Test results for the recombination coefficients in oxygen plasma are shown between 1469 and 2072 K.

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“…Additionally, the effective diffusion coefficient of electrons is expressed as sections are given by the works of Gupta et al [11], except for e-N and e-O pairs, for which the model of Fertig et al [12,13] is used. For composite chemical reactions in thermochemical nonequilibrium flow, we assume that the air is composed…”

Section: Governing Equationsmentioning

confidence: 99%

Numerical analysis on the effect of angle of attack on evaluating radio-frequency blackout in atmospheric reentry

Jung

Kihara

Abe

et al. 2016

Journal of the Korean Physical Society

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A three-dimensional numerical simulation model that considers the effect of the angle of attack was developed to evaluate plasma flows around reentry vehicles. In this simulation model, thermochemical nonequilibrium of flowfields is considered by using a four-temperature model for high-accuracy simulations. Numerical simulations were performed for the orbital reentry experiment of the Japan Aerospace Exploration Agency, and the results were compared with experimental data to validate the simulation model. A comparison of measured and predicted results showed good agreement. Moreover, to evaluate the effect of the angle of attack, we performed numerical simulations around the Atmospheric Reentry Demonstrator of the European Space Agency by using an axisymmetric model and a three-dimensional model. Although there were no differences in the flowfields in the shock layer between the results of the axisymmetric and the three-dimensional models, the formation of the electron number density, which is an important parameter in evaluating radio-frequency blackout, was greatly changed in the wake region when a non-zero angle of attack was considered. Additionally, the number of altitudes at which radio-frequency blackout was predicted in the numerical simulations declined when using the three-dimensional model for considering the angle of attack.

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Transport coefficients for high temperature nonequilibrium air flows

Cited by 24 publications

References 13 publications

Aerodynamic-Heating Analysis of Sample-Return Capsule in Future Trojan-Asteroid Exploration

Aerodynamic-Heating Analysis of Sample-Return Capsule in Future Trojan-Asteroid Exploration

Catalysis of Metallic and Ceramic TPS-Materials

Numerical analysis on the effect of angle of attack on evaluating radio-frequency blackout in atmospheric reentry

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