- Boundary layer suction
Boundary layer suction is technique in which an
air pumpis used to extract the boundary layerat the wingor the inlet of an aircraft. Improving the air flow can reduce drag. Improvements in fuel efficiencyhave been estimated as high as 30%.
The boundary layer
The air molecules at the surface of a wing are effectively stationary (see the
no-slip condition). If the flow is smooth, known as laminar flow, the velocity of the air increases steadily as measurements are taken further away from the surface. However the smooth flow is often disturbed by the boundary layer breaking away from the surface and creating a low pressure region immediately behind the airfoil (see flow separation). This low pressure region results in increased overall drag. Attempts have been made over the years to delay the onset of this flow separation by careful design and smooth surfaces.
Use of suction
As flow separation results from the velocity deficit that is characteristic of boundary layers, suction attempts to remove the boundary layer from the surface before it can separate. The technology was first developed by
Werner Pfenningerin the Second World Warand has been researched almost continuously since. In the 1990s tests [http://www.nasa.gov/centers/dryden/pdf/88653main_H-2382.pdf] were done by NASAwith a F16XL.
Loek Boermans is researching the technology for use in
gliders at the Technical University of Delft. However about 500 watts of power would be needed to drive the pumps and this would mean covering the glider with solar panels and would increase the cost greatly. There are also structural problems to be overcome before the ultimate glider could be manufactured.
pusher configurationis an alternative way to re-energize the boundary layer, but is only used on the fuselage.
* [http://www.dg-flugzeugbau.de/leistung-e.html DGflugzeugbau article]
* [http://www.nasa.gov/centers/dryden/pdf/88653main_H-2382.pdf NASA report on F16 program]
* [http://www.iag.uni-stuttgart.de/transition/publications/trans_publ-200Xwww.htm combination] of
vortex generatorwith suction
Wikimedia Foundation. 2010.
Look at other dictionaries:
Boundary layer — For the anatomical structure, see Boundary layer of uterus. Boundary layer visualization, showing transition from laminar to turbulent condition In physics and fluid mechanics, a boundary layer is that layer of fluid in the immediate vicinity of… … Wikipedia
Divergent boundary — In plate tectonics, a divergent boundary or divergent plate boundary (also known as a constructive boundary or an extensional boundary) is a linear feature that exists between two tectonic plates that are moving away from each other. Divergent… … Wikipedia
Convergent boundary — In plate tectonics, a convergent boundary, also known as a destructive plate boundary (because of subduction), is an actively deforming region where two (or more) tectonic plates or fragments of lithosphere move toward one another and collide. As … Wikipedia
Vortex generator — A vortex generator is an aerodynamic surface, consisting of a small vane that creates a vortex.Peppler, I.L.: From The Ground Up , page 23. Aviation Publishers Co. Limited, Ottawa Ontario, Twenty Seventh Revised Edition, 1996. ISBN 09690054 9 0]… … Wikipedia
SCHRENK — GERMANY (see also List of Individuals) 16.5.1901 Wain/D 18.8.1990 Ottobeuren/D Oskar Schrenk graduated in 1924 from Stuttgart Technical University to submit a PhD thesis to the Aachen University of Technology in 1935. Schrenk became in the… … Hydraulicians in Europe 1800-2000
Future aircraft developments — A number of ideas are being worked on for future aircraft developments. Some are new, some have been tried before but may prove more practicable with modern technology. History tells us that many of these projects will come to nothing, but a few… … Wikipedia
Nissan P35 — The Nissan P35 was a planned Group C car built by Nissan Motors for competition in the World Sportscar Championship. Developed by Nissan Performance Technology Inc. (NPTI), which had formerly raced under the name Electramotive in the United… … Wikipedia
отсос пограничного слоя — (из проточной части турбины) [А.С.Гольдберг. Англо русский энергетический словарь. 2006 г.] Тематики энергетика в целом EN boundary layer suction … Справочник технического переводчика
отсос пограничного слоя в корне лопатки турбины — — [А.С.Гольдберг. Англо русский энергетический словарь. 2006 г.] Тематики энергетика в целом EN boundary layer suction at rootBLSR … Справочник технического переводчика
tornado — tornadic /tawr nad ik, nay dik/, adj. tornadolike, adj. /tawr nay doh/, n., pl. tornadoes, tornados. 1. a localized, violently destructive windstorm occurring over land, esp. in the Middle West, and characterized by a long, funnel shaped cloud… … Universalium