Vortex generator

A vortex generator (VG) is an aerodynamic device, consisting of a small vane usually attached to a lifting surface (or airfoil, such as an aircraft wing)[1] or a rotor blade of a wind turbine.

When the airfoil or the body is in motion relative to the air, the VG creates a vortex,[1][3] which, by removing some part of the slow-moving boundary layer in contact with the airfoil surface, delays local flow separation and aerodynamic stalling, thereby improving the effectiveness of wings and control surfaces, such as flaps, elevators, ailerons, and rudders.

[3] VGs are typically rectangular or triangular, about as tall as the local boundary layer, and run in spanwise lines usually near the thickest part of the wing.

A turbulent boundary layer is less likely to separate than a laminar one, and is therefore desirable to ensure effectiveness of trailing-edge control surfaces.

For swept-wing transonic designs, VGs alleviate potential shock-stall problems (e.g., Harrier, Blackburn Buccaneer, Gloster Javelin).

In tests performed on a Cessna 182 and a Piper PA-28-235 Cherokee, independent reviewers have documented a loss of cruise speed of 1.5 to 2.0 kn (2.8 to 3.7 km/h).

However, these losses are relatively minor, since an aircraft wing at high speed has a small angle of attack, thereby reducing VG drag to a minimum.

Installation of vortex generators can usually bring about a slight reduction in stalling speed of an airplane[4] and therefore reduce the required one-engine-inoperative climb performance.

[8] The one-engine-inoperative rate-of-climb requirement does not apply to single-engine airplanes, so gains in the maximum takeoff weight (based on stall speed or structural considerations) are less significant compared to those for 1945–1991 twins.

[8] However, after a lengthy flight, sufficient fuel may have been used, thereby bringing the aircraft back below the permitted maximum landing weight.