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Investigations of dynamic stall and dynamic stall control on helicopter airfoils

Gardner, Anthony (2016) Investigations of dynamic stall and dynamic stall control on helicopter airfoils. DLR-Forschungsbericht. DLR-FB-2016-55. Habilitation. 181 S.

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Investigations into dynamic stall and dynamic stall control on airfoils are detailed using pitching airfoil experiments and numerical investigations at Mach 0.3, 0.4 and 0.5 on the airfoils EDI-M109, EDI-M112 and OA209. Two-dimensional dynamic stall was investigated, and the effects of the wind tunnel interference, rotation and the finite wing on the three-dimensional stall process were detailed. The curvature of the stall vortex and its effect in reducing the strength of the dynamic stall compared to a two-dimensional treatment was investigated using CFD and experiments with high-speed pressure sensitive paint (PSP) and pressure transducers. Stall control was designed based on its ability to increase the lift in CFD simulations of static stall and implemented by using constant and pulsed blowing with high-pressure air jets in the vertical direction, and the stall was demonstrated to be significantly reduced at all Mach numbers investigated. Optimal mass flux and jet spacing were found for Mach 0.3 and Mach 0.5, and depended on the test case investigated. Optimums for deep stall were around Cμ =0.12 for M=0.3 and Cμ =0.02 for M=0.5. Pulsed blowing was found to be at best as effective as constant blowing with the same mass flux, for the jet configuration and test cases investigated. Flow control by blowing reduced drag for separated flow, but the energy required in compressed air to achieve this was more than the savings in drag, and no cases were found in which flow control resulted in a reduction in total power used.

Item URL in elib:https://elib.dlr.de/109438/
Document Type:Monograph (DLR-Forschungsbericht, Habilitation)
Title:Investigations of dynamic stall and dynamic stall control on helicopter airfoils
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Gardner, AnthonyUNSPECIFIEDhttps://orcid.org/0000-0002-1176-3447UNSPECIFIED
Refereed publication:Yes
Open Access:No
Number of Pages:181
Keywords:Flow control, dynamic stall, helicopter, airfoil, DNW-TWG, DLR-TAU, wind-tunnel interference, 3D effects
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:rotorcraft
DLR - Research area:Aeronautics
DLR - Program:L RR - Rotorcraft Research
DLR - Research theme (Project):L - The Virtual Aerodynamic Rotorcraft (old)
Location: Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Helicopters
Deposited By: Bachmann, Barbara
Deposited On:27 Jan 2017 13:59
Last Modified:06 Feb 2018 16:20

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