Abstract: An arrangement to reduce noise of a wind turbine rotor blade is provided, including a wind turbine rotor blade and a noise reduction device. The noise reduction device includes a serrated extension for at least reducing noise generated from the wind turbine rotor blade, the noise reduction device attached to the trailing edge section. The serrated extension has a number of first and second teeth. The designs of the first and second teeth are differently compared to each other such that suction side noise and pressure side noise are both reduced by the teeth of the serrated extension. Advantageously, the first teeth and the second teeth are arranged in an alternating, periodic pattern and differ from each other by an angle of inclination with regard to a trailing edge streamline and or by its planform shape. Furthermore, a method to reduce noise of a wind turbine rotor blade is provided.

Abstract: A wind turbine rotor blade is provided, having a root end, a tip end, a leading edge section, a trailing edge section and a serrated extension, wherein the serrated extension is attached to the trailing edge section and has at least a first tooth. Furthermore, the wind turbine rotor blade has at least one patterning element for guiding a wind flow which is flowing from the leading edge section to the trailing edge section such that noise which is generated at the trailing edge section is reduced. The patterning element has the shape of a ridge. Advantageously, the ridge-shaped patterning element is located upstream, compared to the first tooth, and/or is located on a surface of the first tooth. Furthermore, a method is provided to reduce noise which is generated at a trailing edge section of a wind turbine rotor blade.

Abstract: An arrangement to reduce noise emission generated by a wind turbine rotor blade is provided. The arrangement includes the rotor blade and a noise reduction device attached thereto. The rotor blade has a suction side and pressure side, leading and trailing edge sections with a trailing edge. The noise reduction device has an inner surface facing the rotor blade trailing edge section, and an outer surface opposite to the inner surface. The noise reduction device has a leading and trailing edge, both connecting the inner and outer surface. The noise reduction device is connected at the rotor blade trailing edge section by a connector. The inner surface has a pre-defined distance to at least one side of the rotor blade chosen so acoustic waves generated at the rotor blade trailing edge section are reflected by the inner surface to reduce noise emission generated by the wind turbine rotor blade.