Thermodynamic performance of carbon in hyperthermal environments

Dolton, T.; Goldstein, H. E.; Maurer, R.

doi:10.2514/6.1968-754

Cited by 14 publications

(11 citation statements)

References 14 publications

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“…This overall density is 4-8 times lower than more-conventional carbon phenolics. In general, the reactions that occur on the surface of PICA, as with other carbon materials [18], can be divided into three regimes: rate-controlled oxidation, diffusioncontrolled oxidation, and sublimation [3]. Arcjet testing by Covington et al [19] at heating rates of 1150 and 1630 W=cm 2 found that diffusion-controlled recession occurs in PICA under those conditions.…”

Section: B Heat Shield Materials Selectionmentioning

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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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 Heat Shield Materials Selectionmentioning

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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“…The diffusion velocity is calculated using Fick's law (Eq. (26)) and a constant Schmidt number (Eq. (27)) which yields acceptable results for species with similar molecular weights.…”

Section: Governing Equations and Gas Phase Modelsmentioning

confidence: 99%

High-Order Shock-Fitting Method for Hypersonic Flow with Graphite Ablation and Boundary Layer Stability

Mortensen

Zhong

2012

42nd AIAA Fluid Dynamics Conference and Exhibit

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A high-order shock-fitting method with thermochemcial nonequilibrium and finite rate boundary conditions for graphite ablation is presented. The method is suitable for direct numerical simulation of boundary layer stability with graphite ablation. Validation with three computational data sets and one set of experimental data is shown. Stability results of the method for a 7 o half angle blunt cone at Mach 15.99 are compared with ideal gas computations that set their wall temperature and wall blowing from the real gas simulation. Weak planar fast acoustic waves are used to perturb the steady base flow. In the nose region wall normal velocity fluctuations increase three orders of magnitude and then decrease rapidly as the wall mass flux decreases on the cone surface. In the nose region perturbation amplitudes of vibration temperature are two orders of magnitude larger than perturbation ampitudes of translation-rotation temperature. NomenclatureC Mass fraction c v,s Species translation-rotation heat capacity at constant volume J/kgK D Species diffusion coefficient m 2 /s e Specific total energy J/kg e v,s Species specific vibration energy J/kg e v Specific vibration energy J/kg h o Stagnation enthalpy J/kg h o s Species heat of formation J/kg M s Species molecular weight kg/mol m Mass flux per area kg/m 2 · s n Surface normal nms Number of molecular species ns Number of species Q T −V,s Species vibration energy transfer rate J/s R Universal gas constant, 8.3143 J/mol · K r Sphere radius s Surface streamline v w Wall normal velocity m/s Subscripts ∞ Freestream n Normal component s Species t Tangential component w Wall Symbols δ ij Kronecker delta ω sRate of species production kg/m 3 · s ρ Density kg/m 3

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“…For C 3 and CO 2 there are three vibrational modes where two modes have a degeneracy of unity and one has a degeneracy of two. The characteristic vibration temperatures and their degeneracies were taken from Park 18 for N 2 , O 2 and NO, from Dolton et al 19 for C 3 , and from McBride 20 for CO 2 , C 2 , CO, and CN. To model chemical nonequilibrium eight dissociation reactions and sixteen exchange reactions are used.…”

Section: Governing Equations and Gas Phase Modelsmentioning

confidence: 99%

Numerical Simulation of Graphite Ablation Induced Outgassing Effects on Hypersonic Boundary Layer Receptivity over a Cone Frustum

Mortensen

Zhong

2013

51st AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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A new thermochemical nonequilibrium linear stability theory code with a gas phase model including multiple carbon species is developed and validated. A high-order shockfitting method with thermochemical nonequilibrium and surface chemistry boundary conditions for graphite ablation along with the new linear stability theory code are used to study hypersonic boundary layer receptivity and stability for a 7 o half angle blunt cone at Mach 15.99. The real gas results are compared with ideal gas computations that set their wall temperature and wall blowing from the real gas simulation. Weak planar fast acoustic waves are used to perturb the steady base flow. A 525 kHz disturbance was found to be unstable for the real gas simulation and stable for both ideal gas simulations. The second mode for the 525 kHz disturbance becomes the dominant instability mode on the cone frustum for the thermochemical nonequilibrium simulation.

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Thermodynamic performance of carbon in hyperthermal environments

Cited by 14 publications

References 14 publications

Significance of Nonequilibrium Surface Interactions in Stardust Return Capsule Ablation Modeling

Significance of Nonequilibrium Surface Interactions in Stardust Return Capsule Ablation Modeling

High-Order Shock-Fitting Method for Hypersonic Flow with Graphite Ablation and Boundary Layer Stability

Numerical Simulation of Graphite Ablation Induced Outgassing Effects on Hypersonic Boundary Layer Receptivity over a Cone Frustum

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