A Comparison of Methods to Compute High-Temperature Gas Thermal Conductivity

Palmer, Grant; Wright, Michael J.

doi:10.2514/6.2003-3913

Cited by 61 publications

(59 citation statements)

References 20 publications

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“…Viscous transport and thermal conductivity are modeled using the binary collision-integral based mixing rules presented by Gupta et al, [17] which have been shown [18,19] to be good approximations of the more accurate Chapman-Enskog relations in this flow regime. The self-consistent effective binary diffusion method [20] is used to compute the species diffusion coefficients.…”

Section: Numerical Methodologymentioning

confidence: 99%

Modeling of Shock Tunnel Aeroheating Data on the Mars Science Laboratory Aeroshell

Wright

Olejniczak

Brown

et al. 2006

Journal of Thermophysics and Heat Transfer

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A series of shots are run in the T5 shock tunnel at California Institute of Technology to measure heating levels on a 70 blunt cone at angle of attack in an environment representative of the Mars Science Laboratory entry. Twenty shots are obtained in CO 2 over a range of enthalpies and pressures chosen to span the laminar and turbulent flow regimes. The data indicate that the lee side turbulent heating augmentation predicted by flight simulations is valid and must be accounted for during the design of the thermal protection system. Computational fluid dynamic simulations are generally in good agreement with the laminar data when employing a supercatalytic wall model, whereas turbulent simulations are in reasonable agreement when a noncatalytic wall model is used. The reasons for this discrepancy are unknown at this time. The turbulent heating augmentation is shown to be inversely related to freestream enthalpy. Changes in angle of attack between 11 and 16 are shown to have minimal impact on measured and computed heating. A transition criterion based on momentum thickness Reynolds number, analogous to that used in flight predictions, predicts onset with reasonable accuracy, although transition is observed to occur later than the current design criterion indicates.

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Section: Numerical Methodologymentioning

confidence: 99%

Modeling of Shock Tunnel Aeroheating Data on the Mars Science Laboratory Aeroshell

Wright

Olejniczak

Brown

et al. 2006

Journal of Thermophysics and Heat Transfer

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“…Vibrationdissociation coupling is currently modeled using the T-Tv approach of Park 14 or with some preliminary implementation of CVDV coupling 15 . Transport properties are appropriately modeled in DPLR for high enthalpy flow 16,17 using the binary collision-integral based mixing rules from Gupta, et al 18 . Diffusion coefficients are modeled using the self-consistent effective binary diffusion (SCEBD) method 19 .…”

Section: A Data-parallel Line-relaxation (Dplr) Codementioning

confidence: 99%

Analysis and Ground Test of Aerothermal Effects on Spherical Capsule Geometries

MacLean

Mundy

Wadhams

et al. 2008

38th Fluid Dynamics Conference and Exhibit

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A review is presented of ground test experiments of a 146-mm spherical capsule model with forebody and aftbody symmetry plane measurements of heating and pressure for a range of enthalpies and Reynolds numbers to obtain a dataset of fundamental validation data for CFD codes and to develop a database for design-of-experiment of future studies. Comparisons with laminar experiments are made using CFD demonstrating the influence of thermochemical non-equilibrium on the aerodynamic and aerothermal character of the body. For laminar flows in nitrogen up to 10MJ/kg, the good agreement with available measurements suggests that the description of the chemical and thermal activity of the gas is adequate. Analysis of the forebody heating found that a catalytic recombination probability of 0.002 to 0.010 was required to match the measured heat flux. For laminar flows in air up to 14 MJ/kg, some significant differences between CFD and measurements highlight the inadequacy of the current chemical and thermal models to predict the state of the gas after the rapid expansion in the nozzle. Analysis of forebody heating in these cases found that catalytic recombination probability near 1.0 was required to match measured heat flux, suggesting that potentially some type of excitation may be involved that is not properly modeled. Finally, the non-equilibrium excitation may be collision related as limited evidence suggests that the phenomenon becomes more benign as the number of collisions increases.

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“…Vibration-dissociation coupling is currently modeled using the T-Tv approach of Park 16 with an exponent on both temperatures of 0.50. Transport properties are appropriately modeled in DPLR for this type of flow 17,18 using the binary collision-integral based mixing rules from Gupta, et al 19 . Diffusion coefficients are modeled using the self-consistent effective binary diffusion (SCEBD) method 20 .…”

Section: A Dplr Codementioning

confidence: 99%

Numerical Assessment of Data in Catalytic and Transitional Flows for Martian Entry

MacLean

Holden²

2006

9th AIAA/ASME Joint Thermophysics and Heat Transfer Conference

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The conditions for a typical run from the MSL phase two study of transition that was performed in the LENS facility have been analyzed to understand the sensitivity to the freestream conditions of the facility. A simplified analysis technique has been used based on energy accounting to freeze specified portions of the chemical or vibrational energy during the expansion process in the nozzle. The effect of freezing this energy results in increased shock standoff distance that better matches the measured shock shape. Based on several cases, it was found that freezing approximately 42% of the total enthalpy of the flow in the vibration mode results in the best agreement with the measured shock shape. This modified condition also results in significantly better agreement with the measured surface heat transfer at the stagnation point and with the measured pressure at the shoulders of the model. Based on this adjusted freestream condition, the surface heat transfer data shows behavior generally consistent with fully-catalytic recombination on the cold wall. This behavior is consistent with previous results obtained in shock tunnel facilities in carbon dioxide, air, and nitrogen. Although the mechanism causing this frozen energy in the flow has not been identified, the sensitivity of the transition onset point of the flowfield to this phenomenon has been estimated to be less than 10% based on a simple transition criterion.

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A Comparison of Methods to Compute High-Temperature Gas Thermal Conductivity

Cited by 61 publications

References 20 publications

Modeling of Shock Tunnel Aeroheating Data on the Mars Science Laboratory Aeroshell

Modeling of Shock Tunnel Aeroheating Data on the Mars Science Laboratory Aeroshell

Analysis and Ground Test of Aerothermal Effects on Spherical Capsule Geometries

Numerical Assessment of Data in Catalytic and Transitional Flows for Martian Entry

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