6. Validation of Fully Coupling Techniques for an Aeroelastic NACA0012

In this section the fully coupled technique is applied to a more realistic text case: the aeroelastic behaviour of a NACA0012 airfoil supported by two linear springs.

The problem consists of a NACA0012 airfoil which is supported by two springs attached to the quarter chord. The configuration is shown in Figure 6, and is described also in [BAT 90], [FAR 90], [FAR 93], [RAU 89]. It is a generic problem of wing divergence: when an aircraft wing in flight is deformed, a moment is induced which will twist the wing. There will be a natural resistance by an elastic moment. The elastic stiffness is independent of the speed, whereas the aerodynamic moment is a direct function: a critical speed may be attained where the stiffness is just sufficient to bear the wing in a disturbed position. By considering a typical wing section supported by springs which represent the effect of the rotation ?, around the elastic centre, with a torsion spring reacting to the pitching motion, and a linear spring reacting to the plunging motion with respect to the vertical displacement. Initially the airfoil is rotated through a small angle as a rigid body, Then this constraint is relaxed to let the wing deflect elastically through the angle a. The aerodynamic action is represented by the lift force L at the aerodynamic centre, and the pitching moment around the same point, M. For the NACA0012 this point...