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

MacLean, Matthew; Holden, Michael

doi:10.2514/6.2006-2946

Cited by 36 publications

(40 citation statements)

References 24 publications

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“…For Run 4, the measured shock is significantly farther away than the prediction. In previous work analyzing CO 2 test cases in the reflected shock tunnel facility, this same behavior was observed 30 . In that case as well, the shock stand-off was measured to be larger than predicted by a much more significant margin and the predicted heat transfer decreased significantly with increased shock stand-off distance.…”

Section: Laminar Forebody Cases In Reacting Airmentioning

confidence: 49%

“…At low to medium enthalpy levels with moderate levels of chemical and vibrational non-equilibrium the method has been found to predict a freestream state that correlates accurately with measurements made in the test section. However, at high enthalpies where there is significant chemical and thermal activity, questions remain about the capability of the physical model to describe the very rapid expansion from reservoir to the test section 29,30 .…”

Section: B Candler Nozzle Codementioning

confidence: 99%

See 1 more Smart Citation

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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Section: Laminar Forebody Cases In Reacting Airmentioning

confidence: 49%

Section: B Candler Nozzle 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 follow-up numerical study found that shock shape and stand-off distance matched experimental observation when 42% of the total energy was artificially frozen in vibration. 11 As discussed by the authors, such a result is clearly aphysical and especially so when one considers that the original calculation had 3.6% of the total energy frozen in vibration. Additionally, frozen vibrational energy was seen to have a greater impact upon the shock stand-off distance than frozen chemical energy.…”

Section: A Cubrc Resultsmentioning

confidence: 99%

Evaluation of Hypervelocity Carbon Dioxide Blunt Body Experiments in an Expansion Tube Facility

Sharma

Swantek

Flaherty

et al. 2011

49th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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This work represents efforts to study high-enthalpy carbon dioxide flows in anticipation of the upcoming Mars Science Laboratory (MSL) and future missions. The current study extends the previous presentation of experimental results by the comparison now with axisymmetric simulations incorporating detailed thermochemical modeling. The work is motivated by observed anomalies between experimental and numerical studies in hypervelocity impulse facilities. In this work, experiments are conducted in the Hypervelocity Expansion Tube (HET) which, by virtue of its flow acceleration process, exhibits minimal freestream dissociation in comparison to reflected shock tunnels. This simplifies the comparison with computational result as freestream dissociation and considerable thermochemical excitation can be neglected. Shock shapes of the Laboratory aeroshell and spherical geometries are compared with numerical simulations. In an effort to address surface chemistry issues arising from high-enthalpy carbon dioxide ground-test based experiments, spherical stagnation point and aeroshell heat transfer distributions are also compared with simulation. The shock stand-off distance has been identified in the past as sensitive to the thermochemical state and as such, is used here as an experimental measureable for comparison with CFD and two different theoretical models. For low-density, small-scale experiments it is seen that models based upon assumptions of large binary scaling values are unable to match the experimental and numerical results. Very good agreement between experiment and CFD is seen for all shock shapes and heat transfer distributions fall within the non-catalytic and super-catalytic solutions.

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“…In contrast, several observations have been previously made in the LENS-I reflected shock tunnel in high-enthalpy reacting air and carbon dioxide test gases where macroscopic discrepancies were clearly visible using this comparison technique. [33,34] The comparison of the measured and predicted surface pressure for all six runs is shown in Fig. 12.…”

Section: Experimental Data Comparisons To Cfdmentioning

confidence: 99%

High Enthalpy Studies of Capsule Heating in an Expansion Tunnel Facility

Dufrene

MacLean

Holden

2012

43rd AIAA Thermophysics Conference

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Measurements were made on an Orion heat shield model to demonstrate the capability of the new LENS-XX expansion tunnel facility to make high quality measurements of heat transfer distributions at flow velocities from 3 km/s (h 0 = 5 MJ/kg) to 8.4 km/s (h 0 = 36 MJ/kg). Thirty-nine heat transfer gauges, including both thin-film and thermocouple instruments, as well as four pressure gauges, and high-speed Schlieren were used to assess the aerothermal environment on the capsule heat shield. Only results from laminar boundary layer runs are reported. A major finding of this test series is that the highenthalpy, low-density flows displayed surface heating behavior that is observed to be consistent with some finite-rate recombination process occurring on the surface of the model. It is too early to speculate on the nature of the mechanism, but the response of the gages on the surface seems generally repeatable and consistent for a range of conditions. This result is an important milestone in developing and proving a capability to make measurements in a ground test environment and extrapolate them to flight for conditions with extreme non-equilibrium effects. Additionally, no significant, isolated stagnation point augmentation ("bump") was observed in the tests in this facility. Cases at higher Reynolds number seemed to show the greatest amount of overall increase in heating on the windward side of the model, which may in part be due to small-scale particulate.

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

Cited by 36 publications

References 24 publications

Analysis and Ground Test of Aerothermal Effects on Spherical Capsule Geometries

Analysis and Ground Test of Aerothermal Effects on Spherical Capsule Geometries

Evaluation of Hypervelocity Carbon Dioxide Blunt Body Experiments in an Expansion Tube Facility

High Enthalpy Studies of Capsule Heating in an Expansion Tunnel Facility

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