Performance of a Low Density Ablative Heat Shield Material

Covington, Michael A.; Heinemann, Jürgen; Goldstein, H. E.; Chen, Y.-K.; Terrazas-Salinas, Imelda; Balboni, John; Olejniczak, Joseph; Martinez, Edward

doi:10.2514/1.12403

Cited by 45 publications

(11 citation statements)

References 4 publications

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“…Adequate arcjet test data were not available for the present work [3,19]. Thus, the results of this study were compared against those of Chen and Milos [8].…”

Section: A Computational Modelsmentioning

confidence: 87%

“…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%

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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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“…Adequate arcjet test data were not available for the present work [3,19]. Thus, the results of this study were compared against those of Chen and Milos [8].…”

Section: A Computational Modelsmentioning

confidence: 87%

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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“…Even if ablated surface roughness caused the flow over the test article to transition to turbulence at some time during the test, it is almost impossible to determine when the transition occurred. Nevertheless, fully turbulent flow simulations over the wedge model were performed 16 American Institute of Aeronautics and Astronautics Ts TC1 TC2 TC3 TC4 TC1 TC3 Ts TC1 TC2 TC3 TC4 TC1 TC2 TC3 to establish upper bounds on the surface recession and temperature, at least for the one turbulence model used: the algebraic Baldwin-Lomax turbulence model.…”

Section: Turbulent Simulationsmentioning

confidence: 99%

“…The ablating material used in these tests was Phenolic Impregnated Carbon Ablator (PICA), which is a low density TPS material developed at NASA ARC in the 1990s. 15,16 PICA was used to construct the heatshield for the Stardust sample-return capsule and the Mars Science Laboratory entry vehicle.…”

Section: 14mentioning

confidence: 99%

Computational Analysis of Arc-Jet Wedge Tests Including Ablation and Shape Change

Goekcen

Chen

Skokova

et al. 2010

10th AIAA/ASME Joint Thermophysics and Heat Transfer Conference

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Coupled fluid-material response analyses of arc-jet wedge ablation tests conducted in a NASA Ames arc-jet facility are considered. These tests were conducted using blunt wedge models placed in a free jet downstream of the 6-inch diameter conical nozzle in the Ames 60-MW Interaction Heating Facility. The fluid analysis includes computational Navier-Stokes simulations of the nonequilibrium flowfield in the facility nozzle and test box as well as the flowfield over the models. The material response analysis includes simulation of two-dimensional surface ablation and internal heat conduction, thermal decomposition, and pyrolysis gas flow. For ablating test articles undergoing shape change, the material response and fluid analyses are coupled in order to calculate the time dependent surface heating and pressure distributions that result from shape change. The ablating material used in these arc-jet tests was Phenolic Impregnated Carbon Ablator. Effects of the test article shape change on fluid and material response simulations are demonstrated, and computational predictions of surface recession, shape change, and in-depth temperatures are compared with the experimental measurements.= mass fraction of species i h = enthalpy, MJ/kg h • = total enthalpy, MJ/kg h •cl = centerline total enthalpy, MJ/kḡ h • = mass-averaged total enthalpy, ρ u h • dA/ ρ u dA, MJ/kg h w = wall enthalpy, MJ/kg I = arc current, Amp M = Mach numbeṙ m = mass flow rate, g/s p = pressure, kPa p box = facility test box pressure, torr p 1 , p 2 = pressure gages on the calibration plate centerline (Fig. 2b), kPa p • = total or stagnation pressure, kPa p •2 = model stagnation pressure or pitot pressure, kPa p s = model surface pressure, kPa Q 6 , Q 7 , Q 8 = heat flux gages on the calibration plate centerline (Fig. 2b), W/cm

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“…대한 안정성을 가지는 것이 장점이기 때문에 열적 노화 및 삭마현상이 발생되는 것을 방지하는 역할을 위한 적용 및 응용 연구에 노력을 기울이고 있다 [1]. 삭마 효과는 고열 또 는 에너지의 축적이 재료 표면에 발생되어 표면을 깎아내 리는 현상을 의미한다 [2].…”

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Microstructure and Ablation Performance of CNT-phenolic Nanocomposites

Wang¹,

Kwon²,

Park³

et al. 2013

Composites Research

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Highly ablation resistant carbon nanotube (CNT)-phenolic composites were fabricated by the addition of low concentrations of CNT nanofiller. Tensile and compressive properties as well as ablative resistance were significantly improved by the addition of only 0.1 and 0.3 wt% of uniformly dispersed CNTs. An oxygen-keroseneflame torch and a field emission scanning electron microscope (FE-SEM) were used to evaluate the ablative properties and microstructures of these CNT-phenolic composites. Thermal gravimetric analysis (TGA) revealed that the ablation rate was lower for the 0.3 wt% CNT-phenolic composites than for neat phenolic or the composite with 0.1 wt% CNT. Ablative mechanisms for all three materials were investigated using this TGA in conjunction with microstructural studies using a FE-SEM. The microstructural studies revealed that CNT acted as an ablation resistant phase at high temperatures, and that the uniformity of dispersion of the CNT played an important role in this resistance to ablation.

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Performance of a Low Density Ablative Heat Shield Material

Cited by 45 publications

References 4 publications

Significance of Nonequilibrium Surface Interactions in Stardust Return Capsule Ablation Modeling

Significance of Nonequilibrium Surface Interactions in Stardust Return Capsule Ablation Modeling

Computational Analysis of Arc-Jet Wedge Tests Including Ablation and Shape Change

Microstructure and Ablation Performance of CNT-phenolic Nanocomposites

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