Inverse Estimation of the Mars Science Laboratory Entry Aeroheating and Heatshield Response

Mahzari, Milad; Braun, Robert D.; White, Todd R.; Bose, Deepak

doi:10.2514/1.a33053

Cited by 39 publications

(19 citation statements)

References 30 publications

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“…Mahzari et al 16 used MEDLI flight data to compare material response predictions from NASA's MR code FIAT 17 with reentry data. They applied the temperatures of the near surface thermocouples as boundary conditions to FIAT.…”

Section: Analysis Methods and Statisticsmentioning

confidence: 99%

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Comparisons of PICA In-depth Material Performance and Ablator Response Modeling from MEDLI Arc Jet Tests

Smith

White

Martin

2015

45th AIAA Thermophysics Conference

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Descent and Landing Instrumentation (MEDLI) project performed extensive arc jet tests for development, qualification, and calibration of instrumented heat shield plugs. The arc jet test results are entered into a comprehensive database so that broad trends across the test series can be compared. Using the nearsurface thermocouple measurements as a boundary condition in numerical simulations, comparisons are made with other thermocouple measurements taken deeper within the TPS test article. The temperature prediction accuracy is quantified for the tested material and material response code and is found to be highly dependent on the distance between the boundary condition thermocouple and the deeper reference thermocouple. It is found that predicted temperatures are consistently greater than measured values indicating the PICA material model is generally conservative for in-depth temperature predictions. NomenclatureSymbols N = Number of samples T = Temperature, • C Subscripts i = index of the sample F = FIAT M = Measured

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Section: Analysis Methods and Statisticsmentioning

confidence: 99%

“…This phenomenon was also not predicted with the flight data using the same TC driving technique. 16 Using the MEDLI arc jet database, further analysis of the "hump" phenomenon has been performed. The analysis, as well as a preliminary model, are presented in Ref.…”

Section: Limitations and Biasmentioning

confidence: 99%

Comparisons of PICA In-depth Material Performance and Ablator Response Modeling from MEDLI Arc Jet Tests

Smith

White

Martin

2015

45th AIAA Thermophysics Conference

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“…As a result, any changes to the nominal environment require reevaluation of the inverse analysis with the new recession profile. The data extracted from inverse analysis are assigned a confidence interval via Monte Carlo analysis [26] of the various input parameters. For MISP1, a recession profile uncertainty is also incorporated into the confidence intervals by allowing the recession rate to be scaled by a constant, which is given a flat distribution between 0.66 and 1.28 (these being the range of errors in [25]) in the Monte Carlo analysis.…”

Section: Comparison With Flight Datamentioning

confidence: 99%

“…In the general formulation of the heat balance equations, it is not possible to separate convective heating from the environment from convective removal of ablation products. Only the in-depth conduction is measured in flight, and other terms must be inferred through inverse analysis [26].…”

Section: Comparison With Flight Datamentioning

confidence: 99%

Radiative Heating During Mars Science Laboratory Entry: Simulation, Ground Test, and Flight

Cruden

Brandis

White

et al. 2016

Journal of Thermophysics and Heat Transfer

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The heat shield of the Mars Science Laboratory was equipped with thermocouple stacks to measure in-depth heating of the thermal protection system during atmospheric entry. The heat load derived from the thermocouples in the stagnation region was found to be 33% lower than corresponding postflight predictions of convective heating alone. It was hypothesized that this difference could be attributed to radiation from the shock-heated gas, a mechanism not considered in preflight analyses of flowfields. To test the hypothesis and quantify the contribution of shock-layer radiation to total surface heating, ground tests and simulations (both flow and radiation) were performed at several points along the best-estimated entry trajectory of the Mars Science Laboratory. The present paper provides an assessment of the quality of the radiation model and its impact to stagnation point heating. The impact of radiative heating is shown to account for 43% of the heat load discrepancy. Additional possible factors behind the remaining discrepancy are discussed. Nomenclature B λ T = Planck (blackbody) function at temperature, T, W∕cm 2 · sr · μm D = shock-tube diameter, m d = shock standoff distance, m e λ x = emission coefficient at position x, W∕cm 2 · sr · μm L λ x = spectral radiance at position x, W∕cm 2 · sr · μm L λ x; θ = spectral radiance at position x at off-normal angle θ, W∕cm 2 · sr · μm _ m = mass blowing rate, kg∕m 2 · s q = heat flux or irradiance Tx = temperature at position x, K v = velocity, m∕s x = position along stagnation line or perpendicular to heat shield, cm or m y = position along heat shield surface, m δ = boundary-layer thickness, m θ = off-normal angle, rad λ = wavelength, nm p c = ablation product density, kg∕m 3

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“…Temperatures on the outer face of a heat shield can exceed 2000 °C under hypersonic entry conditions [4] and oxygencontaining atmospheric gases (e.g., O2, CO2) may dissociate to oxygen atoms in the boundary layer, leading to aggressive oxidation of carbonaceous material. Ablative heat shields are currently overdesigned as a result of large uncertainties in the understanding of the oxidation mechanisms [1,4]. A better understanding of the oxidation process would enable improved carbon-oxygen kinetic rate models for computational fluid dynamics (CFD) [5][6][7] and direct simulation Monte Carlo (DSMC) simulations of heat shield behavior during hypersonic flight [8,9].…”

Section: Introductionmentioning

confidence: 99%

Reactive and Inelastic Scattering Dynamics of Hyperthermal O and O2 from a Carbon Fiber Network

Poovathingal¹,

Qian²,

Murray³

et al. 2021

Preprint

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The reactive and inelastic scattering dynamics of ground-state atomic and molecular oxygen from a carbon fiber network at 1023-1823 K was investigated with a molecular beam-surface scattering technique. A molecular beam containing hyperthermal O and O2 with a mole ratio of 0.92:0.08 and nominal velocity of 8 km s-1 was directed at the network, and time-of-flight distributions of the scattered products were collected at various angles with the use of a rotatable mass spectrometer detector. O atoms exhibited both impulsive scattering (IS) and thermal desorption (TD) dynamics, where the TD O-atom flux increased with surface temperature and the IS O-atom flux remained relatively constant. While the majority of the TD O atoms desorbed promptly after the beam pulse struck the network, signatures of thermal processes occurring over long residence times were also observed. Evidence of O2 reactions was not observed, and the behavior of the inelastically scattered O2 was invariant to the temperature of the network and showed both IS and TD dynamics. The dominant reactive product was CO, whereas CO2 was a minor product. Both these products showed only TD dynamics. The observed flux of CO initially increased with temperature and then reached a plateau above which the flux no longer increased with temperature, over the temperature range studied. Thermally desorbed CO products exited the network promptly or after relatively long residence times, and two populations of CO with long residence times were distinguished. Hysteresis was observed in the temperature-dependent flux of thermally desorbed O and CO, with opposing trends for the two products. This work follows similar studies in our laboratory where the target materials were vitreous carbon and highly oriented pyrolytic graphite. The data suggest that the chemical reactivity of the three forms of sp2 carbon surfaces is similar and that the differences arise from the variations of the morphology.

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Inverse Estimation of the Mars Science Laboratory Entry Aeroheating and Heatshield Response

Cited by 39 publications

References 30 publications

Comparisons of PICA In-depth Material Performance and Ablator Response Modeling from MEDLI Arc Jet Tests

Comparisons of PICA In-depth Material Performance and Ablator Response Modeling from MEDLI Arc Jet Tests

Radiative Heating During Mars Science Laboratory Entry: Simulation, Ground Test, and Flight

Reactive and Inelastic Scattering Dynamics of Hyperthermal O and O2 from a Carbon Fiber Network

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