Vortex generator

Vortex generators are added to the front of a swept-wing in order to maintain steady airflow over the control surfaces at the rear of the wing. They are typically rectangular or triangular, about a centimetre or two in size, and run in lines chordwise at about the thickest part of the wing. They can be seen on the wings and vertical tails of many airliners.

The purpose of the generators are to stick out of the stagnent air near the surface of the wing, and into the freely moving air outside the boundary layer. This layer is typically quite thin, but dramatically reduces speed of the airflow towards the rear of the wing. The generators mix the free stream with the stagnent air to get it moving again, providing considerably more airflow at the rear of the wing and thereby providing the control surfaces with more power. This process is typically referred to as re-energizing the airflow.