As the air curls upward around the tip, it combines with the wash to form a fast-spinning trailing vortex. These vortices increase drag because of energy spent in producing the turbulence. Whenever an airfoil is producing lift, induced drag occurs, and wingtip vortices are created.
Just as lift increases with an increase in AOA, induced drag also increases. This occurs because as the AOA is increased, there is a greater pressure difference between the top and bottom of the airfoil, and a greater lateral flow of air; consequently, this causes more violent vortices to be set up, resulting in more turbulence and more induced drag.
In Figure 4-10, it is easy to see the formation of wingtip vortices. The intensity or strength of the vortices is directly to the weight of the aircraft and inversely to the wingspan and speed of the aircraft. The slower the aircraft, the greater the AOA and the wingtip vortices. Thus, an aircraft will create vortices with maximum strength occurring during climb, and landing phases of flight. These to a particularly dangerous hazard to flight, turbulence.
0 comments:
Post a Comment