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Transition of (quasi-) 2D boundary layers A completed “Patenschaft” (2010-2014)

Costantini, Marco (2015) Transition of (quasi-) 2D boundary layers A completed “Patenschaft” (2010-2014). Airbus PhD Day 2015 „Airbus EG PhD technical session“, 29. - 30. Okt. 2015, Toulouse, France.

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Abstract

Experiments were conducted in the Cryogenic Ludwieg-Tube Göttingen to study the influence of surface imperfections, streamwise pressure gradient, Reynolds number, Mach number, and a non-adiabatic surface on boundary-layer transition. The temperature-sensitive paint technique has been used to detect transition. The influence on boundary-layer transition of surface thermal gradients was examined using a two-dimensional model with a natural laminar flow (NLF) airfoil as cross-section. Various combinations of flow conditions and angles of attack were employed to investigate different stability situations at chord Reynolds numbers up to 13 Mio. The unfavorable impact of surface temperatures larger than the adiabatic-wall temperature was identified to be dependent on the considered boundary-layer-stability situation. For certain stability situations, it was shown that a non-adiabatic model surface can strongly influence the boundary-layer transition location. When transition is induced by a positive (adverse) pressure gradient, however, the sensitivity to the wall-temperature ratio is reduced. Forward-facing steps of different height were installed on two spanwise-invariant wind tunnel models and their effect on transition was examined at high chord Reynolds numbers, various streamwise pressure gradients, and Mach numbers from 0.35 to 0.77. Transition was found to gradually move towards the step location with increasing step Reynolds numbers and relative step height. Larger flow acceleration had a favorable influence on the transition Reynolds number even in the presence of forward-facing steps, but its effect was less pronounced as the step Reynolds number was increased. The plots of the relative change in transition location as a function of the step Reynolds number gave good correlation of the results obtained with both wind tunnel models.

Item URL in elib:https://elib.dlr.de/98745/
Document Type:Conference or Workshop Item (Speech)
Title:Transition of (quasi-) 2D boundary layers A completed “Patenschaft” (2010-2014)
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Costantini, MarcoMarco.Costantini (at) dlr.deUNSPECIFIED
Date:2015
Refereed publication:No
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:Boundary layer transition; forward-facing steps; non-adiabatic surface; Temperature-Sensitive Paint
Event Title:Airbus PhD Day 2015 „Airbus EG PhD technical session“
Event Location:Toulouse, France
Event Type:Other
Event Dates:29. - 30. Okt. 2015
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
Location: Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Experimental Methods
Deposited By: Micknaus, Ilka
Deposited On:16 Dec 2015 08:57
Last Modified:10 May 2016 23:32

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