Abstract: A method for making a windmill blade is provided, whereby problems with glue joints and with exposure of the workers to environmentally hazardous substances are avoided. This is effected by making the windmill blade in a closed mold with a mold core (3) inside mold parts (22, 48) for formation of a mold cavity (51), in which fiber material (45, 47) and core material (46) are placed. After applying vacuum to the mold cavity (51), matrix material (57) is injected via a filling pipe (29), which is placed at a downwardly oriented side edge of the blade during the filling. Hereby is established a flow front (61) which is used for indicating complete filling when this reaches the trailing edge of the blade and penetrates out through overflow apertures.

Abstract: The invention relates to a method and a device for regulating the airflow around a blade of a windmill. The device comprise a spoiler, which is provided with a cavity. The spoiler is mounted to a surface of the blade in connection with an another flow regulating unit, and the spoiler can change the airflow around the blade by assuming different forms. When the spoiler is in a deactivated form no particular changes of the airflow takes place, as the spoiler runs continually and follows the contour of the blade. When the spoiler is in an activated form the airflow, however, is changed in that the spoiler no longer follows the contours of the blade and creates a discontinuity or at least changes the profile of the blade in such way that the airflow conditions are changed. In particular the airflow conditions can be changed so the effect of the second flow regulating unit completely or partly is eliminated.

Abstract: A method for the improvement of wind turbine rotor efficiency blades of a wind turbine rotor with serrated trailing edges each having a plurality of span-wise, periodic indentations, in the form of saw teeth having approximately 60 degrees included angles between adjacent vertices. The efficiency of an existing wind turbine rotor is improved by the attachment of an apparatus to at least part of the trailing edge of the wind turbine blades, the apparatus being in the form of a serrated panel that is fixed to the surface of the blade and has the serrations extending into the airflow behind the trailing edge of the existing blade. The efficiency of a new wind turbine blade is improved by manufacturing the blade with serrations of at least part of the trailing edge of the wind turbine blade.

Abstract: The invention concerns a method for operating a windmill with variable rpm and a directly network connected primary generator. By this method there disposed a regenerative slip generator between the gear of the windmill and the primary generator, whereby the power coming from the slip may be regenerated to the electric network. The total power output from the windmill is kept constant over a certain range of slip. The invention also concerns the specific design of a windmill with such a slip generator.

Abstract: There is disclosed a method for making a windmill blade whereby problems with glue joints and with exposure of the workers to environmentally hazardous substances are avoided. This is effected by making the windmill blade in a closed mold with a mold core (3) inside mold parts (22, 48) for formation of a mold cavity (51), in which fiber material (45,47) and core material (46) are placed. After applying vacuum to the mold cavity (51), matrix material (57) is injected via a filling pipe (29), which is placed at a downwardly oriented side edge of the blade during the filling. Hereby is established a flow front (61) which is used for indicating complete filling when this reaches the trailing edge of the blade and penetrates out through overflow apertures.