Navier-Stokes solutions with surface catalysis for Martian atmospheric entry

Chen, Y.-K; Henline, William D.; Stewart, David A.; Candler, Graham V.

doi:10.2514/3.25468

Cited by 56 publications

(14 citation statements)

References 13 publications

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“…The values of γ w are however consistent with those found in the literature, which also show a large variation. For example, East, Stalker & Baird (1980) use γ w ≈ 3 × 10 −3 which they regard as typical for oxygen and nitrogen recombination on oxidized metallic surfaces with a wall temperature of 300 K. In contrast, Anderson (1973) determined values of γ w using experimental measurements of stagnation-point heat transfer rates in supersonic flow and gave a value for metallic surfaces, including platinum, of 0.09 for 400 ± 100 K. The standard assumption is that γ w increases with temperature, but Chen & Chandler (1993) state, unusually, that it may also be a function of pressure. The free-stream pressures for cases 1 to 4 are included in table 9, and clearly there is no direct relationship between p and γ w in these flows.…”

Section: Comparison With Experimental Resultsmentioning

confidence: 99%

“…Stewart, Rakich &Lanfranco 1983 andScott 1985 and references contained therein). Some more recent studies considered the effects of catalytic walls on a shock/boundary layer interaction (Grumet et al 1991), catalytic effects on a model of Martian atmospheric entry (Chen & Chandler 1993), and hypersonic flow past a sharp cone with finite catalytic walls (Miller et al 1995).…”

Section: Introductionmentioning

confidence: 99%

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High-speed flow with discontinuous surface catalysis

2000

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In a reacting gas flow both gas-phase chemical activity and surface catalysis can increase the rate of heat transfer from the gas to a solid surface. In particular, when there is a discontinuous change in the catalytic properties of the surface, there can be a very large increase in the local heat transfer rate. In this study numerical simulations have been performed for the laminar high-speed flow of a high-temperature, non-equilibrium reacting gas mixture over a flat plate. The surface of the plate is partly catalytic, with the leading region non-catalytic, and a discontinuous change in the catalytic properties of the surface at the catalytic junction. The surface is assumed to be isothermal, and cold relative to the free stream. The gas is assumed to be a mixture of molecular and atomic forms of a diatomic gas in an inert gas forming a thermal bath, giving a three-species mixture with dissociation and recombination of the reactive species. The calculations are performed for a gas with atomic and molecular oxygen in an argon bath, but a full range of gas-phase chemical and surface catalytic effects is considered. Kinetic schemes with frozen gas-phase chemistry, and partial or full recombination of atomic oxygen in the boundary layer are investigated. The catalytic nature of the surface material is given by a catalytic recombination rate coefficient, which varies from zero (non-catalytic) to one (fully catalytic), and the effects on the flow and the surface heat transfer of materials which are non-, partially, or fully catalytic are considered. A self-similar thin-layer analytical model of the change in the gas composition downstream of the catalytic junction is developed. For physically realistic (O(10 −2 )) values of the catalytic recombination rate coefficient, the predictions from this model of the surface values of the atomic oxygen mass fraction and the catalytic surface heat transfer rate are excellent when the only change in the composition of the gas comes from the surface catalysis, and reasonable when there is partial recombination of the gas in the boundary layer due to the gas-phase chemistry. In contrast, when the surface is fully catalytic, the streamwise diffusion terms play a significant role, and the model is not valid. These results should apply to other situations with an attached boundary layer with recombination reactions. A comparison is made between the calculated and experimental measurements of the heat transfer rate at the catalytic junction. With a kinetic scheme which allows partial recombination in the boundary layer, good agreement is found between the experimental and predicted values for surface materials which are essentially non-catalytic. For a catalytic material (platinum), the experimental and numerical heat transfer rates are matched to estimate the value of the catalytic recombination rate coefficient. The values obtained show a considerable amount of scatter, but are consistent with those found in the literature.

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Section: Comparison With Experimental Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High-speed flow with discontinuous surface catalysis

2000

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“…Relative to dissociation energy, vibrational energy is an order of magnitude more important in carbon dioxide than in nitrogen, see for example Rock et al 6 For Martian planetary entry, predicting the aerothermodynamic loading on a vehicle is critical and the role of thermochemical effects has been pointed out in numerous studies. [7][8][9] For example, the increase in transition Reynolds number with increasing stagnation enthalpy was found to be significantly more pronounced in carbon dioxide than in nitrogen. 10,11 In addition to its importance in flight, carbon dioxide thermochemistry can also be significant in flow acceleration to hypersonic velocities in ground testing facilities.…”

Section: A Thermochemistry Of Carbon Dioxide In Ground Test Facilitiesmentioning

confidence: 99%

Expansion Tube Investigation of Shock Stand-Off Distances in High-Enthalpy CO2 Flow Over Blunt Bodies

Sharma

Swantek

Flaherty

et al. 2010

48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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The shock standoff distance in front of a blunt body is sensitive to the thermochemical state of the free stream. Recently, experimental and numerical studies have reported significantly different bow shock profiles in high-enthalpy carbon dioxide flows, a discrepancy that may result from non-equilibrium processes during flow acceleration in ground-based facilities. In this work, an expansion tube is used to create a Mach 5.7 carbon dioxide flow, matching the stagnation enthalpy and the velocity of previous studies. Images of shock layers are obtained for spherical geometries and a scaled model of the Mars Science Lander. Different sphere diameters are used in order to access non-equilibrium and equilibrium stagnation line shock profiles predicted by theory. Mars Science Lander profiles at zero angle of attack are in good agreement with available data from the LENS X expansion tunnel facility, confirming results are facility-independent for the same type of flow acceleration, and indicating the flow velocity is a suitable first-order matching parameter for comparative testing. Heat transfer measurements on the Mars Science Lander are also presented for the three different angle of attacks, and the results are consistent with previous studies. Initial results from a proposed organo-metallic based emission spectroscopy technique for bow shock layer interrogation are also presented.

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“…In studying the Martian atmosphere entry, mainly the limit cases of an ideal catalytic surface (with a maximum rate of heterogeneous recombination of the dissociated carbon dioxide components) and a noncatalytic surface were considered in the literature [16][17][18]. Phenomenological models of the catalytic properties of heat-shield coatings of spacecraft entering the Martian atmosphere based on a detailed analysis of the heterogeneous catalytic reaction mechanism were suggested in [19,20].…”

Section: Introductionmentioning

confidence: 99%

Effect of Physical Adsorption on Heat Fluxes to Catalytic Surfaces in Carbon Dioxide

Kovalev¹,

Afonina²,

Gromov³

2003

AIP Conference Proceedings

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Abstract.A model of the heterogeneous catalysis of a dissociated carbon dioxide mixture on high-temperature heat shield coating has been developed. The model takes into account both chemical and physical adsorption and desorption of oxygen atoms at vacant active sites on the surface; recombination of chemisorbed oxygen atoms with gas phase of O atoms and of CO molecules (Eley -Rideal recombination) and with physisorbed atoms (Langmuir -Hinshelwood recombination). Note that the physisorbed atoms either are desorbed from the surface or diffused to the nearest chemisorbed site. Therefore some of these diffusing atoms will be able either to occupy vacant active sites or to react with chemisorbed atoms.

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Navier-Stokes solutions with surface catalysis for Martian atmospheric entry

Cited by 56 publications

References 13 publications

High-speed flow with discontinuous surface catalysis

High-speed flow with discontinuous surface catalysis

Expansion Tube Investigation of Shock Stand-Off Distances in High-Enthalpy CO2 Flow Over Blunt Bodies

Effect of Physical Adsorption on Heat Fluxes to Catalytic Surfaces in Carbon Dioxide

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