Geissler, Wolfgang and Raffel, Markus and Dietz, Guido and Mai, Holger (2005) Helicopter Aerodynamics with Emphasis Placed on Dynamic Stall. EUROMECH Colloquium 464b Wind Energy, 2005-10-04 - 2005-10-07, Oldenburg, Deutschland (Europa).
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Dynamic Stall is a flow phenomenon which occurs on helicopter rotor blades during forward flight mainly on the retreating side of the rotor disc. This phenomenon limits the speed of the helicopter and its manoeuvrability. Strong excursions in drag and pitching moment are typical unfavourable characteristics of the Dynamic Stall process. However compared to the static polar the lift is considerably increased. Looking more into the flow details it is obvious that a strong concentrated vortex, the Dynamic Stall Vortex, is created during the up-stroke motion of the rotor blade starting very close to the blade leading edge. This vortex is growing very fast, is set into motion along the blade upper surface until it lifts off the surface to be shed into the wake. The process of vortex lift off from the surface leads to the excursions in forces and moment mentioned above. The Dynamic Stall phenomenon does also occur on blades of stall regulated wind turbines under yawing conditions as well as during gust loads. Time scales occurring during this process are comparable on both helicopter and wind turbine blades. In the present paper the different aspects of unsteady flows during the Dynamic Stall process are discussed in some detail. Some possibilities are also pointed out to favourably influence dynamic stall by either static or dynamic flow control devices.
|Document Type:||Conference or Workshop Item (Speech)|
|Title:||Helicopter Aerodynamics with Emphasis Placed on Dynamic Stall|
|In ISI Web of Science:||No|
|Keywords:||dynamic stall, helicopter, rotor blades|
|Event Title:||EUROMECH Colloquium 464b Wind Energy|
|Event Location:||Oldenburg, Deutschland (Europa)|
|Event Dates:||2005-10-04 - 2005-10-07|
|HGF - Research field:||Aeronautics, Space and Transport (old)|
|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|
|Institutes and Institutions:||Institute of Aerodynamics and Flow Technology > Helicopters|
Institute of Aeroelasticity
Institute of Aerodynamics and Flow Technology > High Speed Configurations
|Deposited By:||Daniela Erdmann|
|Deposited On:||29 Aug 2007|
|Last Modified:||27 Apr 2009 13:00|
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