Predictions of Ablating Hypersonic Vehicles Using an Iterative Coupled Fluid/Thermal Approach

Kuntz, David W.; Hassan, Basil; Potter, Donald L.

doi:10.2514/2.6594

Cited by 78 publications

(33 citation statements)

References 23 publications

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“…Ablation in the context of hypersonic flow around vehicles and test bodies has been discussed recently by, for example, Kuntz et al (2001) (numerical calculations) and Silton and Goldstein (2000) (experimental and numerical results). The experimental results of the latter show irregular ablation (cf.…”

Section: Model Calculationsmentioning

confidence: 99%

High-Resolution Simulations of the Impacts of Asteroids into the Venusian Atmosphere II: 3D Models

Korycansky¹,

Zahnle

Low

2002

Icarus

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We compare high-resolution 2D and 3D numerical hydrocode simulations of asteroids striking the atmosphere of Venus. Our focus is on aerobraking and its effect on the size of impact craters. We consider impacts both by spheres and by the real asteroid 4769 Castalia, a severely nonspherical body in a Venus-crossing orbit. We compute mass and momentum fluxes as functions of altitude as global measures of the asteroid's progress. We find that, on average, the 2D and 3D simulations are in broad agreement over how quickly an asteroid slows down, but that the scatter about the average is much larger for the 2D models than for the 3D models. The 2D models appear to be rather strongly susceptible to the "butterfly effect," in which tiny changes in initial conditions (e.g., 0.05% change in the impact velocity) produce quite different chaotic evolutions. By contrast, the global properties of the 3D models appear more reproducible despite seemingly large differences in initial conditions. We argue that this difference between 2D and 3D models has its root in the greater geometrical constraints present in any 2D model, and in particular in the global conservation of enstrophy in 2D that forces energy to pool in large-scale structures. It is the interaction of these artificial large-scale structures that causes slightly different 2D models to diverge so greatly. These constraints do not apply in 3D and large scale structures are not observed to form. A one-parameter modified pancake model reproduces the expected crater diameters of the 3D Castalias reasonably well. c 2002 Elsevier Science (USA)

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Section: Model Calculationsmentioning

confidence: 99%

High-Resolution Simulations of the Impacts of Asteroids into the Venusian Atmosphere II: 3D Models

Korycansky¹,

Zahnle

Low

2002

Icarus

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“…2 was that a simple marching of the coupled problem was employed herein, whereas a predictor-corrector scheme was employed by the authors in Ref. 2. In their approach, the aerothermodynamic environment for each time step was computed by a CFD code and then corrected by iteration at each time step.…”

Section: Applicationmentioning

confidence: 99%

“…However, some efforts at performing a coupled analysis have been reported (Refs. [1][2][3] where computational solutions of the flowfield and the ablating material were performed in an iterative fashion. While much success has been achieved using an uncoupled analysis for design, it is of interest to obtain higher fidelity (coupled) analyses in order to better assess the system and quantify design margins.…”

Section: Introductionmentioning

confidence: 99%

Implementation of a Blowing Boundary Condition in the LAURA Code

Thompson

Gnoffo

2008

46th AIAA Aerospace Sciences Meeting and Exhibit

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“…Stagnation pressures above 80 atm and mass uxes above 10 kg/(m 2 ¢ s) may not be applicable to any known or planned ight, but surface temperatures above 4400 K may be reasonable. 1 Whether transient or steady, such a surface temperature implies sublimation-drivenmass transfer. The best estimates for equilibrium vapor pressure and thence sublimation are derived from the free energy calculations of Leider et al 24 and Lee and Sanborn 25 : The experimental work of Baker et al 12;28 is best interpreted with these calculations rather than JANAF data.…”

Section: Resultsmentioning

confidence: 99%

Comparison of Surface Chemical Kinetic Models for Ablative Reentry of Graphite

Havstad

Ferencz

2002

Journal of Thermophysics and Heat Transfer

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A general formulation for surface chemical reactions is used with a nite element heat conduction code to compare computations of the ablated mass ux from carbon bodies experiencing conditions representative of Earth reentry. Several credible models for the surface chemical kinetics are exercised with the formulation and are compared both to each other and to test data obtained by the Passive Nosetip Technology program in the mid-1970s. Sublimation of C 5 and C 7 is shown to be a concern for surface temperatures greater than about 3900 K. The best match between measurements and the calculations is obtained with surface chemical models that use the usual CO formation reactions and the sublimation of C 1 -C 3 but that also include CN formation and the sublimation of C 5 and C 7 . For surface temperatures above 3500 K and for similar assumptions for the equilibrium vapor pressure and evaporation coef cients of the sublimated species, the net reaction rate approach and the surface site occupation approach give similar ablated mass uxes. Nomenclatureenergy, J/kg F = Gibbs free energy, J/gmol F = radiation view factor f = kinetic rate factor, 1=m 2 s or nondimensional H 0 298 = enthalpy of formation at 298 K, J/gmol h = enthalpy, J/kg h = Planck's constant, J ¢ s k = Boltzmann's constant, J/molecule ¢ K k = reaction rate constant, 1=m 2 s L = number of surface species l = surface species index M = molecular weight, kg/kmol m = mass per molecule, kg P m = mass ux, kg/m 2 s N 0 = Avogadro's number, 1=kmol P = pressure, N/m 2 P 0 = reference pressure, atmosphere, 0.101325 MPa p = pressure, N/m 2 Q = number of surface reactions q = chemical species index P q = heat ux, J/m 2 s R = linear correlation coef cient R u = universal gas constant, J/kmol ¢ K or J/gmol ¢ K r = forward reaction rate, m 2 s S = surface kinetic factor, 1/m 2 s or nondimensional T = temperature, K W = number of gaseous species w = gaseous species index X = mole fraction of gaseous species 125. Senior Member AIAA.°= concentration,kmol/kg " = emissivity " = parameter in surface species reaction constant = stoichiometric coef cient of surface reactants µ = surface species population fractioņ = stoichiometric coef cient of surface products ¹ = stoichiometric coef cient of gaseous products º = stoichiometric coef cient of gaseous reactants ¾ = Stefan-Boltzmann constant, J/m 2 s ¢ K 4 8 = modi cation factor in heat transfer relation Subscripts a = activation ab = ablation abspec = ablated species blow = blowing cw = cold wall diff = diffusion emittradn = emitted radiation eq = equilibrium er = erosion f = forward f = formation condn = uid conduction HAL = heating augmentation level i = mass species index incradn = incident radiation k = element index m = reaction index p = pressure pyrgas = pyrolysis gas q = reaction index r = recovery ref = reference re radn = re ected radiation s = species index s,l = solid to liquid solcondn = solid conduction stag = stagnation T = temperature und = underside u = universal v = volume w = wall º = vibrational 508 Downloaded...

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Predictions of Ablating Hypersonic Vehicles Using an Iterative Coupled Fluid/Thermal Approach

Cited by 78 publications

References 23 publications

High-Resolution Simulations of the Impacts of Asteroids into the Venusian Atmosphere II: 3D Models

High-Resolution Simulations of the Impacts of Asteroids into the Venusian Atmosphere II: 3D Models

Implementation of a Blowing Boundary Condition in the LAURA Code

Comparison of Surface Chemical Kinetic Models for Ablative Reentry of Graphite

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