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Flight dynamics simulation of formation flight for energy saving using LES-generated wake flow fields

Vechtel, Dennis and Fischenberg, Dietrich and Schwithal, Jana (2018) Flight dynamics simulation of formation flight for energy saving using LES-generated wake flow fields. CEAS Aeronautical Journal. Springer. DOI: 10.1007/s13272-018-0318-z ISSN 1869-5590

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Official URL: https://link.springer.com/article/10.1007%2Fs13272-018-0318-z


Wake vortices are an inevitable result of 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 beneficial 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 of saving energy is used by migratory birds, resulting in these birds flying in typical V-formations. This study deals with the question, whether it is possible with a standard autopilot (without a dedicated formation flight mode) to keep the aircraft’s position accurately at a desired position in the wake flow field without accidentally encountering those areas of the wake where steady-state flight is impossible, even in the presence of atmospheric disturbances (e.g. turbulence) and fluctuating vortex core positions. For this purpose, simulations were performed applying three-dimensional flowfields generated with large eddy simulations. Here, even with young vortices, the target sweet spot position varies in the lateral and vertical directions 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 while flying at the same relative position to the leading aircraft. Preliminary simulations with an A320 flying in the wake of an A340, utilizing the regular autopilot of the comprehensive DLR A320 flight simulation model without a dedicated formation-keeping mode, show that the autopilot does not accidentally 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 the outer loop of the regular autopilot.

Item URL in elib:https://elib.dlr.de/120778/
Document Type:Article
Title:Flight dynamics simulation of formation flight for energy saving using LES-generated wake flow fields
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Vechtel, DennisDennis.Vechtel (at) dlr.deUNSPECIFIED
Fischenberg, DietrichDietrich.Fischenberg (at) dlr.deUNSPECIFIED
Schwithal, JanaJana.Schwithal (at) dlr.dehttps://orcid.org/0000-0003-3554-0560
Date:July 2018
Journal or Publication Title:CEAS Aeronautical Journal
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:No
DOI :10.1007/s13272-018-0318-z
Keywords:Formation flight, Large-eddy Simulation, Fuel save Simulation study, Flight control, Autopilot
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 - Flight Physics
Location: Braunschweig
Institutes and Institutions:Institute of Flight Systems > Flight Dynamics and Simulation
Deposited By: Vechtel, Dennis
Deposited On:09 Jul 2018 15:06
Last Modified:31 Jul 2019 20:18

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