Strongly Coupled Computation of Material Response and Nonequilibrium Flow for Hypersonic Ablation

44th AIAA Thermophysics Conference

2013

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This paper describes the coupling of a Navier-Stokes solver to a material response code to simulate nonequilibrium gas-surface interactions. The Navier-Stokes solver used in this study is LeMANS, which is a three-dimensional computational fluid dynamics code that can simulate hypersonic reacting flows including thermo-chemical nonequilibrium effects. The material response code employed in this study is MOPAR, which uses the one-dimensional control volume finite-element method to model heat conduction and pyrolysis gas behavior. This coupling is demonstrated using a test case based on the Stardust sample return capsule. Coupled simulations are performed at three different trajectory conditions. The effects of the pyrolysis gas chemistry are evaluated by assuming that the gas is either in chemical equilibrium or composed entirely of non-reacting phenol. The results show that the non-reacting pyrolysis gas assumption produces higher convective heat fluxes, surface temperatures, and mass blowing rates. These effects are mainly due to the composition of the pyrolysis gas. The additional species produced by the pyrolysis gas in the chemical equilibrium case react with oxygen and nitrogen atoms in the gas-phase. This results in fewer atoms participating in the exothermic surface reactions, which reduces the heat transfer to the vehicle.

Section: A Navier-stokes Solvermentioning

confidence: 99%

mentioning

confidence: 99%

Coupled Flow Field Simulations of Charring Ablators with Nonequilibrium Surface Chemistry

Alkandry

Boyd

44th AIAA Thermophysics Conference

2013

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“…To account for the injection of metals into the flow from the vehicle surface, a blowing boundary condition is used in LeMANS [11]. The temperature, T w , blowing mass flow rate, _ m w w v w , and the species mass fraction, Y w;i , are all specified at the wall.…”

Section: Modeling Of Atv Entry Emissionsmentioning

confidence: 99%

Hypersonic Flow and Radiation Analysis of the Automated Transfer Vehicle Jules Verne

Boyd¹,

Journal of Spacecraft and Rockets

Wiebenga

et al. 2013

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Hypersonic flowfield and radiation analyses are performed before and after flight to study the physical conditions experienced by the automated transfer vehicle Jules Verne during reentry before breakup. Results are compared to those obtained with a miniature Echelle spectrograph operated from an airborne platform, measuring the flux density of atomic line emissions from oxygen and nitrogen, as well as many metals. Molecular emissions from CN and AlO are also detected. The vehicle lost its solar panels at 86 km and first broke up at 75 km. The main cargo cabin held together until 68 km. Postflight analyses focus on altitudes of 86, 75, and 68 km. A first analysis includes only air species, correctly predicting the observed oxygen and nitrogen atomic line intensities. N 2 band emission is systematically overestimated by at least a factor of 20, indicating a need for revision of the radiation model for this system. A second analysis includes blowing of metals (aluminum, sodium, potassium, and magnesium) from the vehicle surface. The blowing rates are inferred by requiring the computed and measured emissions to match. Magnesium and aluminum originate from ablation of structural elements, while sodium and potassium may have originated as impurities in paint.

“…The second type of application addresses compressible, reacting flows: for example, the interaction of an atmospheric flow over the porous heat shield of a re-entry vehicle [11][12][13]. Previous works on surface coupling have been based on a methodical analysis of all physical phenomena, which is then presented as surface balance equations [6].…”

Section: Flux-balancing At the Boundarymentioning

confidence: 99%

An introduction to the derivation of surface balance equations without the excruciating pain

International Journal of Heat and Mass Transfer

Zhang

Tagavi

2017

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Analyzing complex fluid flow problems that involve multiple coupled domains, each with their respective set of governing equations, is not a trivial undertaking. Even more complicated is the elaborate and tedious task of specifying the interface and boundary conditions between various domains. This paper provides an elegant, straightforward and universal method that considers the nature of those shared boundaries and derives the appropriate conditions at the interface, irrespective of the governing equations being solved. As a first example, a well-known interface condition is derived using this method. For a second example, the set of boundary conditions necessary to solve a baseline aerothermodynamics coupled plain/porous flow problem is derived. Finally, the method is applied to two more flow configurations, one consisting of an impermeable adiabatic wall and the other an ablating surface.