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Active Management of Flap-Edge Trailing VorticesThe vortex hazard produced by large airliners and increasingly larger airliners entering service, combined with projected rapid increases in the demand for air transportation, is expected to act as a major impediment to increased air traffic capacity. Significant reduction in the vortex hazard is possible, however, by employing active vortex alleviation techniques that reduce the wake severity by dynamically modifying its vortex characteristics, providing that the techniques do not degrade performance or compromise safety and ride quality. With this as background, a series of experiments were performed, initially at NASA Langley Research Center and subsequently at the Berlin University of Technology in collaboration with the German Aerospace Center. The investigations demonstrated the basic mechanism for managing trailing vortices using retrofitted devices that are decoupled from conventional control surfaces. The basic premise for managing vortices advanced here is rooted in the erstwhile forgotten hypothesis of Albert Betz, as extended and verified ingeniously by Coleman duPont Donaldson and his collaborators. Using these devices, vortices may be perturbed at arbitrarily long wavelengths down to wavelengths less than a typical airliner wingspan and the oscillatory loads on the wings, and hence the vehicle, are small. Significant flexibility in the specific device has been demonstrated using local passive and active separation control as well as local circulation control via Gurney flaps. The method is now in a position to be tested in a wind tunnel with a longer test section on a scaled airliner configuration. Alternatively, the method can be tested directly in a towing tank, on a model aircraft, a light aircraft or a full-scale airliner. The authors believed that this method will have significant appeal from an industry perspective due to its retrofit potential with little to no impact on cruise (devices tucked away in the cove or retracted); low operating power requirements; small lift oscillations when deployed in a time-dependent manner; and significant flexibility with respect to the specific devices selected.
Document ID
20090008660
Acquisition Source
Langley Research Center
Document Type
Conference Paper
Authors
Greenblatt, David (National Academy of Sciences - National Research Council Hampton, VA, United States)
Yao, Chung-Sheng (NASA Langley Research Center Hampton, VA, United States)
Vey, Stefan (Technische Univ. Berlin, Germany)
Paschereit, Oliver C. (Technische Univ. Berlin, Germany)
Meyer, Robert (Deutsche Forschungsanstalt fuer Luft- und Raumfahrt Berlin, Germany)
Date Acquired
August 24, 2013
Publication Date
June 23, 2008
Subject Category
Aircraft Stability And Control
Report/Patent Number
LF99-7241
Meeting Information
Meeting: 4th AIAA Flow Control Conference
Location: Seattle, WA
Country: United States
Start Date: June 23, 2008
End Date: June 26, 2008
Funding Number(s)
WBS: WBS 877868.02.07.07.05.02
Distribution Limits
Public
Copyright
Public Use Permitted.

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