Technical Field
The present invention relates to a method for applying a serrated rear edge to a blade rear edge of a rotor blade. The present invention additionally relates to such a serrated rear edge, and to a rotor blade having such a serrated rear edge. The invention also relates to a wind turbine having at least one rotor blade having a serrated rear edge.
Description of the Related Art
Serrated rear edges of rotor blades of wind turbines, especially so-called horizontal-axis wind turbines, are known. They are disposed at the blade rear edge of the rotor blade, at least in a portion, and then constitute there, essentially, the new rear edge of the rotor blade. This new rear edge, i.e., this serrated rear edge, thus creates a serrated contour, in particular having long, pointed serrations, which influences the aerodynamic behavior in this region. For such serrated rear edges, the term “serrations” is also generally used.
It has been found that such serrations can have a positive effect on the aerodynamic behavior of the rotor blades, such that nowadays rotor blades are increasingly being constructed with such serrations. For older wind turbines, it is desirable to retrofit such serrations. In the case of rotor blades that, in the region of their rear edge, have a cavity extending along the rear edge, this cavity can be sawn open, and such a serrated rear edge can be inserted in the resultant opening. Another possibility consists in providing the serrated rear edge as an approximately V-shaped profile, in order to attach it, with the V-shaped opening, on the previously existing rear edge of the rotor blade. For this purpose, this existing rear edge would have to be milled appropriately on the pressure and the suction side in order to create a match to this profile. For example, FIG. 1 of the German patent application DE 197 43 694 A1 discloses such a V-shaped profile, although not for a serrated rear edge, but for a rear edge without serrations.
If the described preconditions, such as the longitudinally extending cavity, are not present, or if the resource input for retrofitting such a serrated rear edge is to be kept at a low level, especially for reasons of cost and time, the methods for retrofitting that are described above may be disadvantageous.
The German Patent and Trade Mark Office, in the priority application relating to the present PCT application, has searched the following prior art: DE 197 43 694 A1, DE 10 2008 007 908 A1, DE 10 2011 052 930 A1, DE 10 2012 109 989 A1, EP 2 667 019 A2 and WO 2014/048 437 A1.
USPTO Backgrounds
USPTO Backgrounds