Analysis and Ground Test of Aerothermal Effects on Spherical Capsule Geometries

MacLean, Matthew; Mundy, Erik; Wadhams, Timothy; Holden, Michael; Parker, Ronald A.

doi:10.2514/6.2008-4273

Cited by 14 publications

(16 citation statements)

References 37 publications

(47 reference statements)

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“…In Eq. (15), R N represents the radius of curvature of the spherical capsule geometry used in the experiments by MacLean et al [5]. In Eq.…”

Section: A Description Of Deterministic Fay-riddell Correlationmentioning

confidence: 99%

“…To represent an uncertain variable from each uncertainty source, we consider recombination efficiency and the binary collision integral for N 2 -O interaction. A recent work by MacLean et al [5], which included both experimental and numerical studies on the hypersonic aerodynamic heating of spherical capsule geometries, demonstrated a significant variation of the surface heat flux with different recombination efficiencies (e.g., catalytic wall conditions) and at different freestream velocities. Another study by Bose et al [6] demonstrated the effect of uncertainty in the binarycollision integrals on surface heat flux for a Martian entry problem.…”

mentioning

confidence: 98%

“…Another study by Bose et al [6] demonstrated the effect of uncertainty in the binarycollision integrals on surface heat flux for a Martian entry problem. The UQ in CFD simulations of the current study is performed for a particular test case and capsule geometry selected from the work of MacLean et al [5], where the freestream velocity for the experiment was 4167 m=s at a stagnation enthalpy of 9:9 MJ=kg. In the current work, the freestream velocity is modeled as an inherent uncertain variable described with a normal probability distribution.…”

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confidence: 99%

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Uncertainty and Sensitivity Analysis for Reentry Flows with Inherent and Model-Form Uncertainties

Hosder¹,

Bettis²

2012

Journal of Spacecraft and Rockets

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The objective of this paper is to introduce a computationally efficient methodology for the quantification of mixed (inherent and model-form) uncertainties and global sensitivity analysis (SA) in hypersonic reentry flow computations. The uncertainty-quantification (UQ) approach is based on the second-order UQ theory, using a stochastic response surface obtained with nonintrusive polynomial chaos. The global nonlinear SA is based on Sobol variance decomposition, which uses polynomial chaos expansions. The methodology was used to quantify the uncertainty and sensitivity information for surface heat flux to the spherical nonablating heat shield of a reentry vehicle at an angle of attack of 0 deg. Three uncertainty sources were treated in computational fluid dynamics simulations: inherent uncertainty in the freestream velocity, model-form uncertainty in the recombination efficiency used in partially catalytic wall-boundary condition, and model-form uncertainty in the binary-collision integrals. The SA showed that the velocity and recombination efficiency were the major contributors to the heat-flux uncertainty for the reentry case considered. The UQ and SA were performed with three different levels of input uncertainty in velocity, which revealed the importance of characterizing the velocity with well-defined uncertainty levels in the study of reentry flows because the variations in this quantity can drastically impact the accuracy of the heat-flux prediction. Nomenclature C = mass fraction CoV = coefficient of variation, D 1=2 = D = statistical variance H = enthalpy, J h = enthalpy, J=kg h D = dissociation enthalpy, J=kg k = multiplicative factor Le = Lewis number n = number of random variables p = pressure, N=m 2 _ q = heat transfer rate, W=m 2 R N = radius of curvature, m S = Sobol index S T = total Sobol indices T = temperature, K V = velocity, m=s x = lateral direction of the flow = spectral modes = stochastic output variable = recombination efficiency h f = heat of formation, J=kg = coefficient of viscosity, kg=m s = mean = standard random variable a = standard aleatory uncertain variable e = standard epistemic uncertain variable = density, kg=m 3 = random basis function 1;1 = diffusion collision integral 2;2 = viscosity collision integral Subscripts e = boundary layer edge o = total or stagnation condition sp = stagnation point w = wall 1 = freestream

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“…In Eq. (15), R N represents the radius of curvature of the spherical capsule geometry used in the experiments by MacLean et al [5]. In Eq.…”

Section: A Description Of Deterministic Fay-riddell Correlationmentioning

confidence: 99%

mentioning

confidence: 98%

mentioning

confidence: 99%

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Uncertainty and Sensitivity Analysis for Reentry Flows with Inherent and Model-Form Uncertainties

Hosder¹,

Bettis²

2012

Journal of Spacecraft and Rockets

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“…This smaller capsule is a scaled-down version of the split-sting mount studied in the previous section of this work. The data taken on the forebody of this smaller capsule has been studied extensively by MacLean, et al 19 . The detailed geometry and test conditions for the tests are given there so they will not be repeated here, but the model is shown installed in the facility in Fig 35. All tests were performed at a nominal Mach number near 10 at a range of enthalpies in both air and nitrogen from cold flow up to approximately 15 MJ/kg.…”

Section: Experimental Study On the Effect Of Jet Interaction In Thmentioning

confidence: 99%

Experimental and Numerical Study of Laminar and Turbulent Base Flow on a Spherical Capsule

MacLean

Mundy

Wadhams

et al. 2009

47th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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A review is presented of ground test measurements on a spherical capsule model with aftbody measurements of heating and pressure for a range of enthalpies and Reynolds numbers to obtain datasets of fundamental validation data for CFD codes and to develop a database for design-of-experiment of future studies. These measurements have been made using several sting mounting arrangements and significant differences in heating of up to 100% have been observed. Increasing relative heat transfer with increasing Reynolds numbers has been observed which may be indicative of transitional behavior on the aftbody. The relative heating on the aftbody has also been found to be exceptionally sensitive to the flow total enthalpy. Measurements of jet and cavity interaction on the otherwise smooth aftbody have also been explored and a non-dimensional correlation developed for design of future test articles. Finally, comparisons with the US3D code using a DES methodology have been made with the data and generally good agreement to within one standard deviation has been found. The most significant limitations have been found in modeling transition and in matching heating and pressure locally near separation points.

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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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Analysis and Ground Test of Aerothermal Effects on Spherical Capsule Geometries

Cited by 14 publications

References 37 publications

Uncertainty and Sensitivity Analysis for Reentry Flows with Inherent and Model-Form Uncertainties

Uncertainty and Sensitivity Analysis for Reentry Flows with Inherent and Model-Form Uncertainties

Experimental and Numerical Study of Laminar and Turbulent Base Flow on a Spherical Capsule

High Enthalpy Studies of Capsule Heating in an Expansion Tunnel Facility

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