Boundary Layer Stability Analysis of Mars Science Laboratory Aeroshell

Johnson, Heath B.; Candler, Graham V.; Wright, Michael J.

doi:10.2514/6.2006-920

Cited by 13 publications

(9 citation statements)

References 17 publications

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“…3,4 Blunt re-entry capsules with a sphere-cone shaped forebody like the Mars Science Laboratory (MSL) support modal growth of boundary-layer instabilities on the conical part of the heat shield strong enough to trigger laminarturbulent transition. [5][6][7] Configurations where the forebody consists of a spherical segment only, like the Apollo capsule or the Orion Crew Exploration Vehicle (CEV), require a much higher Reynolds number for the onset of modal disturbance growth. 8 Owing to the strong bow shock, the boundary-layer edge Mach number remains subsonic or slightly supersonic on the spherical heat shield, which excludes the possibility of second mode amplification.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Roughness Effects on Transition on Spherical Capsules

Hein

Theiß

Giovanni

et al. 2018

2018 AIAA Aerospace Sciences Meeting

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The state of the boundary layer on space re-entry vehicles significantly affects the design of the thermal protection system. However, the physical mechanism that leads to the laminar-turbulent boundary-layer transition on blunt spherical capsules remains an open question in literature. This work numerically assesses the potential of roughness-induced non-modal disturbance growth on re-entry capsules with a spherical-section forebody by optimal transient-growth theory and direct numerical simulation. Two different sets of wind-tunnel experiments are considered. Optimal transient-growth studies have been performed for the blunt capsule experiments at Mach 5.9 in the Hypersonic Ludwieg tube Braunschweig (HLB) of the Technische Universität Braunschweig. In some of these measurements, the capsule model was equipped with a specifically designed patch of distributed micron-sized surface roughness. The transient-growth results for the HLB capsule are compared to corresponding numerical data for a Mach 6 blunt capsule experiment in the Adjustable Contour Expansion (ACE) facility of the Texas A&M University (TAMU) at lower Reynolds number. Similar trends are observed for both configurations. In particular, a rather low maximum energy gain is noted for the surface temperature conditions of the experiments. It is shown that the surface temperature dependence of the optimal transient-growth results is very similar for both capsule configurations. Moreover, the generation of stationary disturbances by well-defined roughness patches on the capsule surface is studied for the conditions of the HLB experiment using direct numerical simulations (DNS). To help explain the observed laminar-turbulent transition downstream of the roughness patch in some of the HLB capsule experiments, additional simulations were carried out to study the evolution of unsteady perturbations within the steady disturbance flow field due to the roughness patch. However, the DNS did not provide any indication of modal or non-modal disturbance growth in the wake of the roughness patch, and hence, the physical mechanism underlying the observed onset of transition remains unknown.

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Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Roughness Effects on Transition on Spherical Capsules

Hein

Theiß

Giovanni

et al. 2018

2018 AIAA Aerospace Sciences Meeting

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“…For the design of future returning space vehicles, those correlations should be replaced by the methods based on stability theory and transient growth considerations as demanded by Reshotko [2]. So far, stability analyses have only been performed for the MSL capsule, where transition was dominated by ¦rst-mode and cross- §ow instabilities [3,4] and recently by Theiss et al [5] for an Apollo-shaped capsule. Because of a strong favourable pressure gradient, the boundary layer in the latter investigation did not feature any ampli¦ed modal disturbances at similar freestream conditions to [4].…”

Section: Introductionmentioning

confidence: 99%

Investigation on the wake flow instability behind isolated roughness elements on the forebody of a blunt generic reentry capsule

Theiß

Hein

2017

Progress in Flight Physics

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Numerical results on modal disturbance growth in the wake §ow downstream of a roughness element submerged in the boundary layer of a typical reentry capsule at an angle of attack are presented. Laminar base §ow computations were conducted for di¨erent roughness heights and planform shapes. The modal instability characteristics of the wake §ow were studied by spatial two-dimensional (2D) eigenvalue analysis. For all cases considered, the varicose wake modes are most ampli¦ed in terms of maximum N -factors, with the cylindrical roughness element being the most e¨ective shape.

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“…The transition stability of this geometry has already been shown to be highly marginal 36 , and it is not clear that the parameter Re θ /M is a valid transition criterion for this flowfield. However, it is hoped that it will provide at least a qualitative insight and that it is consistent with the approximate nature of this entire analysis.…”

Section: Impact Of Frozen Energy On Transition Behaviormentioning

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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Boundary Layer Stability Analysis of Mars Science Laboratory Aeroshell

Cited by 13 publications

References 17 publications

Numerical Investigation of Roughness Effects on Transition on Spherical Capsules

Numerical Investigation of Roughness Effects on Transition on Spherical Capsules

Investigation on the wake flow instability behind isolated roughness elements on the forebody of a blunt generic reentry capsule

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

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