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Numerical Investigation of Roughness Effects on Transition on Spherical Capsules

Hein, Stefan and Theiß, Alexander and Di Giovanni, Antonio and Stemmer, Christian and Schilden, Thomas and Schröder, Wolfgang and Paredes, Pedro and Choudhari, Meelan M. and Li, Fei and Reshotko, Eli (2018) Numerical Investigation of Roughness Effects on Transition on Spherical Capsules. In: AIAA SciTech Forum - 55th AIAA Aerospace Sciences Meeting, 210059. AIAA. AIAA Scitech 2018, 8.-12. Jan. 2018, Kissimmee, Florida, USA. doi: 10.2514/6.2018-0058. ISBN 978-162410524-1.

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Official URL: https://arc.aiaa.org/doi/abs/10.2514/6.2018-0058


The state of the boundary layer on space reentry 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 nonmodal disturbance growth on reentry 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. 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 by 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 nonmodal disturbance growth in the wake of the roughness patch; and hence, the physical mechanism underlying the observed onset of transition remains unknown.

Item URL in elib:https://elib.dlr.de/119305/
Document Type:Conference or Workshop Item (Speech)
Title:Numerical Investigation of Roughness Effects on Transition on Spherical Capsules
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Di Giovanni, AntonioTU MünchenUNSPECIFIED
Stemmer, ChristianTU MünchenUNSPECIFIED
Schilden, ThomasRWTH AachenUNSPECIFIED
Schröder, WolfgangRWTH AachenUNSPECIFIED
Paredes, PedroNASA Langley Research CenterUNSPECIFIED
Choudhari, Meelan M.NASA Langley Research CenterUNSPECIFIED
Li, FeiNASA Langley Research CenterUNSPECIFIED
Reshotko, EliCase Western Reserve UniversityUNSPECIFIED
Date:January 2018
Journal or Publication Title:AIAA SciTech Forum - 55th AIAA Aerospace Sciences Meeting
Refereed publication:No
Open Access:No
Gold Open Access:No
In ISI Web of Science:No
DOI :10.2514/6.2018-0058
Series Name:AIAA 2018-0058
Keywords:laminar-turbulent transition, blunt re-entry capsule, surface roughness, transient growth, direct numerical simulation (DNS)
Event Title:AIAA Scitech 2018
Event Location:Kissimmee, Florida, USA
Event Type:international Conference
Event Dates:8.-12. Jan. 2018
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:fixed-wing aircraft
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Simulation and Validation (old)
Location: Göttingen
Institutes and Institutions:Institute for Aerodynamics and Flow Technology > High Speed Configurations, GO
Deposited By: Hein, Dr.-Ing. Stefan
Deposited On:22 Mar 2018 14:36
Last Modified:15 Nov 2019 14:26

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