Boundary layer suction

Boundary layer suction

Boundary layer suction is technique in which an air pump is used to extract the boundary layer at the wing or the inlet of an aircraft. Improving the air flow can reduce drag. Improvements in fuel efficiency have 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 Pfenninger in the Second World War and has been researched almost continuously since. In the 1990s tests [http://www.nasa.gov/centers/dryden/pdf/88653main_H-2382.pdf] were done by NASA with 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.

See also

* The pusher configuration is an alternative way to re-energize the boundary layer, but is only used on the fuselage.

External links

* [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 generator with suction


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать реферат

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

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”