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Experimental Investigation of Air Jets to Control Shock-Induced Dynamic Stall

Gardner, Anthony Donald and Richter, Kai and Mai, Holger and Neuhaus, Dietmar (2014) Experimental Investigation of Air Jets to Control Shock-Induced Dynamic Stall. Journal of the American Helicopter Society, 59 (2), pp. 1-11. American Helicopter Society. doi: 10.4050/JAHS.59.022003. ISSN 0002-8711.

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Official URL: http://ingentaconnect.com/content/ahs/jahs/2014/00000059/00000002/art00003


This paper shows experimental results for dynamic stall control on a dynamically pitching OA209 airfoil at Mach 0.5, with Reynolds numbers 1.9 × 106 and 0.85 × 106 . The control was by supersonic constant blowing on the suction side of the airfoil. Dry compressed air was blown normal to the airfoil chord, from portholes at 10% chord, with diameter 1% chord. At both Reynolds numbers, the OA209 without blowing experienced shock-induced stall with a hysteresis in lift and pitching moment around the static values, rather than the overshoot in forces typically associated with a dynamic stall vortex. The forces and the stall control were primarily functions of the maximum angle of attack, with full control of stall possible for maximum angles of attack of 14◦ and less. The higher Reynolds number required relatively more blowing (higher Cq , Cμ ) to control the dynamic stall. Drag was reduced 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. Increasing the jet spacing resulted in equivalent flow control with less air use. Jets spaced at 20% chord and mass flux ratio Cq = 0.004 (momentum ratio Cμ = 0.016) resulted in a reduction of the pitching moment peak by 60%. The flow control with air jets was uncritical regarding the aerodynamic damping.

Item URL in elib:https://elib.dlr.de/89037/
Document Type:Article
Title:Experimental Investigation of Air Jets to Control Shock-Induced Dynamic Stall
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Gardner, Anthony Donaldtony.gardner (at) dlr.deUNSPECIFIED
Richter, Kaikai.richter (at) dlr.deUNSPECIFIED
Mai, Holgerholger.mai (at) dlr.deUNSPECIFIED
Neuhaus, Dietmardietmar.neuhaus (at) dlr.deUNSPECIFIED
Journal or Publication Title:Journal of the American Helicopter Society
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
DOI :10.4050/JAHS.59.022003
Page Range:pp. 1-11
Publisher:American Helicopter Society
Keywords:Control Shock-Induced, higher Reynolds number, dynamic stall, aerodynamic damping
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:Rotorcraft (old)
DLR - Research area:Aeronautics
DLR - Program:L RR - Rotorcraft Research
DLR - Research theme (Project):L - The Virtual Aerodynamic Rotorcraft (old)
Location: Göttingen , Köln-Porz
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Helicopters
Institute of Aeroelasticity > Aeroelastic Experiments
Institute of Materials Physics in Space > Leitungsbereich MP
Deposited By: Micknaus, Ilka
Deposited On:12 May 2014 08:58
Last Modified:08 Mar 2018 18:45

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