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High Reynolds number testing of a laminar airfoil under forced harmonic pitching oscillations at cryogenic conditions

Mai, Holger and Hebler, Anne and Koch, Stefan (2019) High Reynolds number testing of a laminar airfoil under forced harmonic pitching oscillations at cryogenic conditions. IFASD 2019 - International Forum on Aeroelasticity and Structural Dynamics, 10.-13. Juni 2019, Savannah, GA (USA).

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Abstract

Steady and unsteady aerodynamic testing of a pitching 2D laminar airfoil model was conducted at high Reynolds numbers under cryogenic conditions. The influence of the unsteady laminar-turbulent boundary layer transition on the aeroelastic stability and flutter behavior was investigated to assess the risk of applying this technology to transport aircraft. In first tests the influence of free transition on a typical laminar CAST-10/2 airfoil on its aeroelastic stability could be derived. As the aim of the present test was to obtain unsteady aerodynamic data for an oscillating laminar airfoil in the high Reynolds number regime, a new hydraulic pitching mechanism was built that could be operated in an environment of low temperatures down to 100 K. Furthermore a new wind-tunnel model with NLF-0415 airfoil shape was built and equipped with unsteady pressure sensors, hot-film sensors and accelerometers. During the test systematic variations of the Mach number at constant Reynolds number and a variation of the Reynolds number at constant Mach number were performed. Steady lift and moment polars were recorded at Reynolds numbers of up to 14·106. As a first result, nonlinear behavior as already found for the CAST-10/2 airfoil in the transonic regime for low Reynolds numbers of 2·106, can also be found for the NLF-0415 airfoil for Reynolds numbers of up to 8·106.

Item URL in elib:https://elib.dlr.de/127974/
Document Type:Conference or Workshop Item (Speech)
Title:High Reynolds number testing of a laminar airfoil under forced harmonic pitching oscillations at cryogenic conditions
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Mai, HolgerHolger.Mai (at) dlr.deUNSPECIFIED
Hebler, Anneanne.hebler (at) dlr.dehttps://orcid.org/0000-0002-5450-9211
Koch, StefanStefan.Koch (at) dlr.deUNSPECIFIED
Date:2019
Refereed publication:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:laminar airfoil, laminar-turbulent transition, flutter, unsteady aerodynamics, cryogenic wind tunnel, NLF-0415
Event Title:IFASD 2019 - International Forum on Aeroelasticity and Structural Dynamics
Event Location:Savannah, GA (USA)
Event Type:international Conference
Event Dates:10.-13. Juni 2019
Organizer:AIAA
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 - Flight Physics
Location: Göttingen
Institutes and Institutions:Institute of Aeroelasticity > Aeroelastic Experiments
Deposited By: Grischke, Birgid
Deposited On:26 Jun 2019 17:20
Last Modified:26 Jun 2019 17:20

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