Zusammenfassung der Ressource
Boundary Layer Control
- Air particles flow in two directions over a wing, one at right angles to the
leading edge, other follows leading edge
- Produces spanwise flow
- Spanwise flow thickens boundary layer towards the wing tip,
especially during low speed flight with high angle of attack
- Wing fences reduce effects of spanwise flow
- Flow separation risk is increased with spanwise flow
- Vortex Generator
- Improves boundary layer control
- Small and low aspect ratio wing placed vertically on surface of a large wing
- Produces lift and has associated tip vortex which is comparable to induced drag
- Vortex is large relative to generator because of small aspect ratio
- Takes high energy air from outside boundary layer and mixes it with low energy air in boundary layer
- Generator must be right size and right location to go through boundary layer
- Stall Strips (Wedges)
- TYpically consist of small piece of aluminium triangular cross section, often 6 - 12 inches long
- Initiates flow separation earlier than at other positions along the wing
- Causes wing root to stall before outer portions, ensuring a progressive outward stall
- Minimizes risk of spinning and giving maximum aileron control throughout stall