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Analysis of Formation Flight for Energy Saving Using LES-Generated Wake Flow Fields

Vechtel, Dennis and Fischenberg, Dietrich and Schwithal, Jana (2016) Analysis of Formation Flight for Energy Saving Using LES-Generated Wake Flow Fields. Deutscher Luft- und Raumfahrt-Kongress, 13.-15. Sep. 2016, Braunschweig.

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Wake vortices are an inevitable result of the lift generation and can pose a threat to any aircraft, which accidentally encounters the wake of another aircraft. However, wake vortices can also be used in a benefi-cial way. Due to its rotational direction, the air flows upwards outside of the vortex pair, giving additional energy to any aircraft located in these regions. This method to save energy is performed by migratory birds, resulting in birds flying in a typical V-formation. This study deals with the question, whether it is possible with a standard autopilot to keep the aircraft’s position accurately in the optimal region of the fuel saving sweet spot with atmospheric disturbances and fluctuating vortex core positions without accidentally encountering the hazardous areas of the wake. For this purpose, a simulation study was performed applying three-dimensional flow fields generated with large eddy simulations (LES). Here, even with young vortices the target sweet spot position can vary in lateral and vertical direction with a magnitude of a few metres at a constant distance behind the generator aircraft. Hence, also the vortex induced forces and moments change continuously. Preliminary simulations with an A320 flying in the wake of an A340, utilizing the regular autopi-lot of the DLR A320 simulation model without a dedicated formation keeping mode, show that, nevertheless, the autopilot does not incidentally encounter hazardous regions within the wake. This indicates that it could be sufficient for a formation keeping autopilot for civil transport aircraft to be designed as outer loop for the regular autopilot.

Item URL in elib:https://elib.dlr.de/106127/
Document Type:Conference or Workshop Item (Speech)
Title:Analysis of Formation Flight for Energy Saving Using LES-Generated Wake Flow Fields
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Fischenberg, DietrichDLR-FT-FDSUNSPECIFIED
Schwithal, Janajana.schwithal (at) dlr.deUNSPECIFIED
Date:15 September 2016
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:No
Keywords:Formation Flight; LES; FLight Simulation
Event Title:Deutscher Luft- und Raumfahrt-Kongress
Event Location:Braunschweig
Event Type:national Conference
Event Dates:13.-15. Sep. 2016
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 - Systems and Cabin
Location: Braunschweig
Institutes and Institutions:Institute of Flight Systems > Flight Dynamics and Simulation
Deposited By: Vechtel, Dennis
Deposited On:20 Sep 2016 15:23
Last Modified:09 Mar 2017 16:04

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