Stagnation-Point Heat Transfer Rates for Pioneer-Venus Probes

Park, Chul; Ahn, Hyo-Keun

doi:10.2514/2.6426

Cited by 69 publications

(20 citation statements)

References 23 publications

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“…Park's method is also more applicable to low dynamic pressures. The current work has the original nonequilibrium capability in MAT integrated back into the program, but replaces the earlier models with an expanded finite rate model proposed by Park that contains oxidation and additional reactions [6,7,20].…”

Section: B Multicomponent Ablative Thermochemistry Surface Interactimentioning

confidence: 98%

“…Various studies by Park and Ahn [6], Park [7], and Chen and Milos [8] have examined nonequilibrium surface interactions on heat shields reentering the Earth's or other planets' atmospheres; however, these efforts typically have not extended the models in those studies to compute ablation. Park derived a numerical model [7] for the Stardust return capsule that used finite rate ablation to calculate the species concentrations on the surface, with a reaction set that included sublimation, nitridation, and one oxidation reaction.…”

mentioning

confidence: 98%

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Significance of Nonequilibrium Surface Interactions in Stardust Return Capsule Ablation Modeling

Beerman

Lewis

Starkey

et al. 2009

Journal of Thermophysics and Heat Transfer

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The gas-surface modeling of high-density materials exposed to high-pressure atmospheric reentry conditions was extended to include low-density materials interacting with low-pressure atmospheric conditions. The fully implicit ablation thermal response code and multicomponent ablation thermochemistry program were extended to include nonequilibrium surface conditions for the Stardust return capsule. The Stardust return capsule reentered Earth's atmosphere experiencing low pressure and had a low-density heat shield material. The material response of the Stardust return capsule was previously only modeled with surface equilibrium. Validation against Stardust reentry flight data showed that the equilibrium assumption led to an overprediction of recession and that the inclusion of nonequilibrium reduced the overprediction of this parameter. Incorporating the Park finite rate model nonequilibrium surface conditions led to a reduction in the calculated value of recession at the stagnation point from 1.12 to 0.72 cm in a nominal simulation of the Stardust return capsule. The nonequilibrium recession was closer to the measured recession of 0.65 cm. Incorporating nonequilibrium conditions also decreased the calculated total heat load from 28 to 19 kJ=cm 2 . The improved material response method is applicable to a range of reentries, including future missions such as the Orion crew exploration vehicle. NomenclatureB = preexponential factor, s 1 B 0 = dimensionless mass blowing rate, _ m= e u e C M C H = Stanton number for heat transfer C i = mass fraction for species i C M = Stanton number for mass transfer c p = specific heat, J=kg-K D i = diffusion coefficient for species i, m 2 =s E = activation temperature, K F = view factor H r = recovery enthalpy, J=kg h = enthalpy, J=kg h = partial heat of charring, J=kg k = Boltzmann constant, J=K M = molecular weight, kg=mole m = mass, kg _ m = mass flux, kg=m 2 s p = pressure, N=m 2 q c = conductive heat flux, W=m 2 q rad = radiative heat flux, W=m 2 T = temperature, K u = velocity, m=s v w = mass injection velocity, m=s x = moving coordinate system, y s, m Y = element mass fraction y = stationary coordinate, m = surface absorption = efficiency of gas-surface interaction = volume faction of resin " = surface emissivity = blowing reduction parameter = density, kg=m 3 = Stefan-Boltzmann constant, W=m 2 K 4 = decomposition reaction order Subscripts c = char d = density component e = boundary-layer edge g = pyrolysis gas i = surface species k = element or gaseous base species s = surface v = original w = wall

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Section: B Multicomponent Ablative Thermochemistry Surface Interactimentioning

confidence: 98%

mentioning

confidence: 98%

Significance of Nonequilibrium Surface Interactions in Stardust Return Capsule Ablation Modeling

Beerman

Lewis

Starkey

et al. 2009

Journal of Thermophysics and Heat Transfer

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“…A reaction efficiency is a function of experimental conditions and may depend in general on temperature, pressure, gas and surface composition, and competing surface reaction mechanisms. In simple ablation models, surface reactions are assumed to be first order in reactant concentration, uncoupled and operating in parallel, with rates specified by temperature-dependent reaction efficiencies extracted from various experiments [4][5][6]. In more sophisticated surface reaction models that consider competing rate processes (adsorption, desorption, Eley-Rideal and Langmuir-Hinshelwood reactions, sublimation, etc.)…”

Section: Introductionmentioning

confidence: 99%

Laboratory Investigation of the Active Nitridation of Graphite by Atomic Nitrogen

Zhang¹,

Pejaković²,

Marschall³

et al. 2012

Journal of Thermophysics and Heat Transfer

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“…Due to the high enthalpy of the freestream, thermochemical nonequilibrium was expected in the shock layer, excluding the use of Park et al [22] and Park and Ahn's [23] one-temperature assumption for CO 2 -N 2 flows. A two-temperature model was thus used to simulate the thermal nonequilibrium, coupling translational-rotational and vibrational-electron-electronic modes.…”

Section: A Flowfield Modelingmentioning

confidence: 99%

Venus Entry Flow over a Decomposing Aeroshell in X2 Expansion Tube

Banerji¹,

Leyland²,

Fahy³

et al. 2018

Journal of Thermophysics and Heat Transfer

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The effects of phenolic decomposition on shock-layer radiation were investigated experimentally in X2 expansion tube for a Venus entry flow. A carbon-phenolic composite aeroshell was subjected to a flow with a flight equivalent velocity of 9.35 km ⋅ s −1 . Emission spectroscopy was used to measure boundary-layer radiation in parts of the ultraviolet (380-480 nm) and visible (620-700 nm) spectrum, and it was compared to control measurements taken with a cold steel model. With the composite model in place, the calibrated spectral radiance measured was seen to increase for the O (645.598 nm) atomic line and the N 2 (391.22 nm) band head, but it decreased for the C 2 Swan band (420-480 nm). The recorded data were then compared to numerical spectra produced by two-dimensional axisymmetric computational fluid dynamic simulations coupled to a radiation solver. Both of the applied chemistry models overpredicted CN violet Δν 0 band radiation, which demonstrated strong self-absorption at these conditions. Better comparisons were achieved for the C 2 Swan band radiation. At visible wavelengths, peak intensities were underestimated by the numerical simulations. Several possible reasons were hypothesized for these discrepancies.

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Stagnation-Point Heat Transfer Rates for Pioneer-Venus Probes

Cited by 69 publications

References 23 publications

Significance of Nonequilibrium Surface Interactions in Stardust Return Capsule Ablation Modeling

Significance of Nonequilibrium Surface Interactions in Stardust Return Capsule Ablation Modeling

Laboratory Investigation of the Active Nitridation of Graphite by Atomic Nitrogen

Venus Entry Flow over a Decomposing Aeroshell in X2 Expansion Tube

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