Coupled Fluids-Radiation Analysis of a High-Mass Mars Entry Vehicle

Palmer, Grant; Allen, Gary; Tang, Chun; Brown, J. J.

doi:10.2514/6.2011-3495

Cited by 8 publications

(6 citation statements)

References 29 publications

(50 reference statements)

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“…As a rule of thumb, when Γ > 0.01, it generally indicates that the flow is strongly coupled [38]. For the condition being studied, stagnation-point radiative heat flux was calculated to be 3410 W ⋅ cm −2 via a tangent slab approximation, based on stagnation line temperatures and species number densities calculated and described in Sec.…”

Section: B Radiation Modelingmentioning

confidence: 99%

Venus Entry Flow over a Decomposing Aeroshell in X2 Expansion Tube

Banerji¹,

Leyland²,

Fahy³

et al. 2018

Journal of Thermophysics and Heat Transfer

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The effects of phenolic decomposition on shock-layer radiation were investigated experimentally in X2 expansion tube for a Venus entry flow. A carbon-phenolic composite aeroshell was subjected to a flow with a flight equivalent velocity of 9.35 km ⋅ s −1 . Emission spectroscopy was used to measure boundary-layer radiation in parts of the ultraviolet (380-480 nm) and visible (620-700 nm) spectrum, and it was compared to control measurements taken with a cold steel model. With the composite model in place, the calibrated spectral radiance measured was seen to increase for the O (645.598 nm) atomic line and the N 2 (391.22 nm) band head, but it decreased for the C 2 Swan band (420-480 nm). The recorded data were then compared to numerical spectra produced by two-dimensional axisymmetric computational fluid dynamic simulations coupled to a radiation solver. Both of the applied chemistry models overpredicted CN violet Δν 0 band radiation, which demonstrated strong self-absorption at these conditions. Better comparisons were achieved for the C 2 Swan band radiation. At visible wavelengths, peak intensities were underestimated by the numerical simulations. Several possible reasons were hypothesized for these discrepancies.

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Section: B Radiation Modelingmentioning

confidence: 99%

Venus Entry Flow over a Decomposing Aeroshell in X2 Expansion Tube

Banerji¹,

Leyland²,

Fahy³

et al. 2018

Journal of Thermophysics and Heat Transfer

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“…In recent years, a number of studies have been performed to determine the vehicle and mission requirements that would enable the human exploration of Mars [1][2][3][4]. High-mass crewed Mars vehicles would be larger than previously-flown unmanned robotic spacecraft and would experience higher levels of radiative heating.…”

Section: Introductionmentioning

confidence: 99%

Experimental Validation of CO2 Radiation Simulations

Palmer

Cruden

2012

43rd AIAA Thermophysics Conference

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“…if the coupling is neglected. The dependance of the ratio between the actual radiative eating and what it would be if the flow was adiabatic q r /q r ad and the Goulard number Γ has indeed been demonstrated numerically or used by various authors (see for example [42,65,80,125,136,141,155,183,188,186,210]). As depicted in figures 4.1 for different atmospheres, the function linking both (using the logarithm of Γ) can be expressed in the form of a sigmoïd: decreasing from a certain value slightly smaller than 1.0 for uncoupled flows down to another constant value for fully-coupled flows.…”

Section: Non-adiabatic Radiative Heat Fluxmentioning

confidence: 81%

“…For example, Hollis et al suggest to use the same a = 3 for Titan atmospheric entry [80], as do Palmer et al for Mars entry due to the preponderance of CO [141]. Additional radiation coupling studies for Titan can be found in [136,183].…”

Section: Non-adiabatic Radiative Heat Fluxmentioning

confidence: 99%

On binary scaling and ground-to-flight extrapolation in high-enthalpy facilities

Looringhe¹,

Arwid²

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The binary scaling law is commonly used to study the aerothermodynamics of hypersonic vehicles in high-enthalpy facilities. It enables the duplication of the shock layer in the vicinity of the stagnation point, including binary chemistry and nonequilibrium processes, through the reproduction of the Péclet and wall Damköhler numbers. These are both conserved through the duplication of the composition of the gas, the free-stream enthalpy h ∞ and the product of a density and a length-scale of the flow ρL.Binary scaling is built on the assumption of a flow devoid of radiation coupling and governed by binary reactions. These two conditions drastically narrow down the envelope of flows for which binary scaling can be used. Moreover, diffusive transport and wall chemistry have never been addressed although they can have an important impact on the wall heat flux.The first part of this thesis consists in an effort to better understand the theoretical role and effect of the different assumptions done to build the binary scaling. It is first shown that diffusive transport and wall chemistry should scale appropriately. Second, that non-binary chemistry will cause the shock layer in the laboratory flow to be hotter and less dissociated. A methodology is proposed to identify clearly what free-stream conditions will affect the least the flow variables of interest. Lastly, that radiation coupling will be weaker in the laboratory flow than in flight, causing the enthalpy contained in the shock layer to be greater in the laboratory flow.These findings are verified in the second part with two experiments. The first experiment was performed in the Plasmatron plasma wind tunnel at the von Karman Institute, Belgium. Binary scaled boundary layers were obtained for flows where diffusion and wall chemistry contribute significantly to the heat flux. The stagnation point heat fluxes were measured and exhibit a good agreement with the theoretical scaling law. This also validates the use of the binary scaling law in subsonic high-enthalpy facilities.The second experiment was performed in the X2 expansion tube at the Centre for Hypersonics, Australia. Three flows were obtained over cylinders of different radii, adapting the free-stream density according to the binary scaling law. The free-stream conditions were determined in order to ensure a significant radiative coupling. Its effect could clearly be identified through measurements of the shock standoff distance, stagnation point heat flux, and shock layer radiation. A new method, based on a mix of experiments, computational fluid dynamics, and informed use of engineering correlations is proposed to perform ground to flight extrapolation for cases for which the radiative coupling is non-negligible. Declaration by authorThis thesis is composed of my original work, and contains no material previously published or written by another person except where due reference has been made in the text. I have clearly stated the contribution by others to jointly-authored works that I have include...

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Coupled Fluids-Radiation Analysis of a High-Mass Mars Entry Vehicle

Cited by 8 publications

References 29 publications

Venus Entry Flow over a Decomposing Aeroshell in X2 Expansion Tube

Venus Entry Flow over a Decomposing Aeroshell in X2 Expansion Tube

Experimental Validation of CO2 Radiation Simulations

On binary scaling and ground-to-flight extrapolation in high-enthalpy facilities

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