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Impact of Coupled Radiation and Ablation on the Aerothermodynamics of Meteor EntriesA high-fidelity approach for simulating the aerothermodynamic environments of meteor entries is developed. Two primary components of this model are coupled radiation and coupled ablation. Coupled radiation accounts for the impact of radiation on the flow field energy equations, while coupled ablation explicitly models the injection of ablation products within the flow field and radiation simulations. For a meteoroid with a velocity of 20 km/s, coupled radiation reduces the stagnation point radiative heating by over 60%. For altitudes below 40 km, the impact of coupled radiation on the flow field structure is shown to be fundamentally different, as a result of the large optical thicknesses, than that seen for reentry vehicles, which do not reach such altitudes at velocities greater than 10 km/s. The impact of coupled ablation (with coupled radiation) is shown to provide at least a 70% reduction in the radiative heating relative to the coupled-radiation-only cases. This large reduction is partially the result of the low ionization energies, relative to air species, of ablation products. The low ionization energies of ablation products, such as Mg and Ca, provide strong photoionization and atomic line absorption in regions of the spectrum that air species do not. MgO and CaO are also shown to provide significant absorption. Turbulence is shown to impact the distribution of ablation products through the shock- layer, which results in up to a 100% increase in the radiative heating downstream of the stagnation point. To create a database of heat transfer coefficients the developed model was applied to a range of cases. This database considered velocities ranging from 14 to 20 km/s, altitudes ranging from 20 to 50 km, and nose radii ranging from 1 to 100 m. The heat transfer coefficients from these simulations are below 0.045 for the range of cases (with turbulence), which is significantly lower than the canonical value of 0.1.
Document ID
20170006495
Acquisition Source
Langley Research Center
Document Type
Conference Paper
Authors
Johnston, Christopher O.
(NASA Langley Research Center Hampton, VA, United States)
Stern, Eric C.
(NASA Ames Research Center Moffett Field, CA, United States)
Date Acquired
July 12, 2017
Publication Date
June 5, 2017
Subject Category
Fluid Mechanics And Thermodynamics
Report/Patent Number
NF1676L-27230
Meeting Information
Meeting: AIAA Thermophysics Conference
Location: Denver, CO
Country: United States
Start Date: June 5, 2017
End Date: June 9, 2017
Sponsors: American Inst. of Aeronautics and Astronautics
Funding Number(s)
WBS: WBS XYZ123
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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