On Catalytic Recombination Rates in Hypersonic Stagnation Heat Transfer

Goulard, R.

doi:10.2514/8.7444

Cited by 309 publications

(89 citation statements)

References 11 publications

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“…The latter is suggested as 2∕3 by Lees [4]. Goulard [5] suggested a similar heat flux equation for frozen boundary layer with arbitrary catalytic efficiencies at the wall and at any degree of dissociation: …”

Section: Literature Review a Local Heat Transfer Simulationmentioning

confidence: 99%

Hypersonic Aerothermochemistry Duplication in Ground Plasma Facilities: A Flight-to-Ground Approach

Sakraker

Turchi

Chazot

2015

Journal of Spacecraft and Rockets

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High conservative safety margins, applied to the design of spacecraft thermal protection systems for planetary entry, need to be reduced for higher efficiency of future space missions. Ground testing of such protection systems is of great importance during the design phase. This study covers a methodology for simulating the complex hypersonic entry aerothermochemistry in a plasma wind tunnel for a given spacecraft geometry without any assumption on axisymmetry or bluntness. A demonstration of this proposed methodology is made on the Qubesat for Aerothermodynamic Research and Measurements on AblatioN, QARMAN mission, which is a rectangular reentry CubeSat with a cork-based ablative thermal protection system in the front unit. The reacting boundary-layer profiles of the hypersonic entry probe compare well with the ones developing at the stagnation region of the plasma test model, defined with the proposed flight-to-ground duplication method.

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Section: Literature Review a Local Heat Transfer Simulationmentioning

confidence: 99%

Hypersonic Aerothermochemistry Duplication in Ground Plasma Facilities: A Flight-to-Ground Approach

Sakraker

Turchi

Chazot

2015

Journal of Spacecraft and Rockets

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“…For detailed study of heterogeneous recombination, the PES for interaction of Al 4 O 6 cluster with oxygen molecule and two separated oxygen atoms (adsorbed Figure 7 The PES for interaction of Al4O6 cluster with oxygen molecule (1) and two separated oxygen atoms (2) Figure 8 Coe©cient of heterogeneous recombination of oxygen atoms on the Al2O3: experimental data (samples A (1), B (2), and C (3) from [14]) and calculated QCT results (4) and gas-phase) at the di¨erent internuclear distances were calculated (Fig. 7).…”

Section: Progress In Flight Physicsmentioning

confidence: 99%

“…The heat §uxes to surfaces with di¨erent catalytic properties can di¨er by several times. Despite the fact that since the 1950s [1], it has been well known that heterogeneous atom recombination signi¦cantly a¨ects heat transfer at hypersonic §ight velocities, the mechanisms and rates of the processes, which determine the interaction between the gas and the surface, have been much less closely studied than the kinetics and the homogeneous chemical reaction rates. The complexity of the problem of determining the catalytic properties of the surface is associated with the fact that even at room temperatures, there are no direct methods of measuring the recombination coe©cients γ i and chemical energy accommodation β i .…”

Section: Introductionmentioning

confidence: 99%

Simulation of oxygen atom heterogeneous recombination on Al₂O₃fromab initioapproach

Kovalev

Kroupnov

Pogosbekian

et al. 2012

Progress in Flight Physics

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To analyze the catalytic properties of heat shield materials of space vehicles, the cluster model of oxygen atom adsorption on Al 2 O 3 surface is constructed on the basis of density functional theory. The potential energy surface (PES) corresponding to orientation interaction of the O atom with this cluster is calculated. It was found a number of important PES features for subsequent description of heterogeneous catalytic processes with an application of molecular dynamics methods. In the framework of quasi-classical approach, the modeling of heterogeneous recombination of oxygen atoms on the surface of cluster through Eley Rideal mechanism was conducted by molecular dynamics methods. Modeling results revealed that for correct description of investigated process, PES has to be calculated with taking into account internal relaxation of some top cluster layers.

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“…The effects of catalysis on surface heat transfer rates have been studied since at least the late 1950s by workers such as Lees (1956), Fay & Riddell (1958), Goulard (1958), Chung &Anderson (1961), andInger (1963). Most of the early work concerned the stagnation-point heat transfer rate within a stream of dissociated air, with the main emphasis on reducing the diffusive surface heat flux by using non-catalytic material.…”

Section: Introductionmentioning

confidence: 99%

“…The catalytic recombination rate coefficient is defined as the fraction of the total number of atoms impinging on a unit surface area that recombine per unit time (see e.g. Goulard 1958or Miller et al 1995 and, therefore, has a range of 0 to 1. The upper limit refers to a fully catalytic material where the surface reactions occur instantaneously, and the lower limit to a non-catalytic wall with no surface reactions.…”

Section: Introductionmentioning

confidence: 99%

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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On Catalytic Recombination Rates in Hypersonic Stagnation Heat Transfer

Cited by 309 publications

References 11 publications

Hypersonic Aerothermochemistry Duplication in Ground Plasma Facilities: A Flight-to-Ground Approach

Hypersonic Aerothermochemistry Duplication in Ground Plasma Facilities: A Flight-to-Ground Approach

Simulation of oxygen atom heterogeneous recombination on Al₂O₃fromab initioapproach

High-speed flow with discontinuous surface catalysis

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On Catalytic Recombination Rates in Hypersonic Stagnation Heat Transfer

Cited by 309 publications

References 11 publications

Hypersonic Aerothermochemistry Duplication in Ground Plasma Facilities: A Flight-to-Ground Approach

Hypersonic Aerothermochemistry Duplication in Ground Plasma Facilities: A Flight-to-Ground Approach

Simulation of oxygen atom heterogeneous recombination on Al2O3fromab initioapproach

High-speed flow with discontinuous surface catalysis

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Simulation of oxygen atom heterogeneous recombination on Al₂O₃fromab initioapproach