Turbulator
From Wikipedia, the free encyclopedia
A turbulator is a device for improving the flow of air over a wing. See also aerodynamics
When air flows over the wing of an aircraft, there is a layer of air called the boundary layer between the wing's surface and where the air is undisturbed. Depending on the profile of the wing, the air will often flow smoothly in a thin boundary layer across much of the wing's surface. However there comes a point, the transition point, in which the boundary layer breaks away from the surface of the wing. Beneath the separated layer, bubbles of stagnant air form, creating additional drag because the boundary layer becomes thicker as more air gets caught up in it.
These bubbles can be reduced or even eliminated by shaping the airfoil to move the transition point or by adding a device, a turbulator that trips the boundary layer into turbulence. The turbulent layer remains thin and close to the wing's surface and so stagnant bubbles cannot form.
In gliders the turbulator is often a thin zig-zag strip that is placed on the underside of the wing and sometimes on the fin. The DG 300 glider used small holes in the wing surface to blow air into the boundary layer, but there is a risk that these holes will become blocked by polish, dirt and moisture.
For the aircraft with low Reynolds numbers (i.e. where minimizing turbulence and drag is a major concern) such as gliders, the small increase in drag from the turbulator at higher speeds is minor compared with the larger improvements at best glide speed, at which the glider can fly the furthest for a given height.
