The present disclosure relates to a method of optimizing a rotor blade of a wind turbine, wherein said rotor blade extends from a rotor-blade coupling to a rotor-blade tip in a rotor-blade longitudinal direction with a rotor-blade length, having an aerodynamical profile extending between a leading edge and a trailing edge, wherein said method comprises the following steps: designing of said rotor blade for design environmental conditions including at least one design air density, with said designing comprising providing a sound-protection means, the sound protection means comprising at least one bristle, within a blade external region of said rotor blade the latter being defined as the 50% of said rotor-blade length abutting said rotor-blade tip; providing an air density at the installation site of said wind turbine; comparing said air density with said design air density; and increasing the induction factor by increasing a density factor of said sound-protection means when said air density is lower than said design air density.

A method for manufacturing a shell 36 and 38, is disclosed. The method includes laying one or more layers of fibres, on a surface of a mould 9 to form at least a portion of a shell half structure 36 and 38. A first panel 11 defined with noise reduction members 11a is positioned adjacent to the one or more layers of fibres on the surface of the mould 9. Further, resin is infused through the one or more layers of fiber and the first panel 11 and is subsequently cured to obtain the shell half structure 36 or 38, where the first panel 11 with noise reduction members 11a adheres to the shell half structure 36 and 38 upon curing the infused resin.

A wind turbine comprising a tower, a nacelle, a hub, and three or more wind turbine blades is disclosed. The wind turbine further comprises blade connecting tension members, each blade connecting tension member extending between a connection point at one wind turbine blade and a connection point at a neighbouring wind turbine blade. Each blade connecting tension member comprises a tension member core, and a surface texture providing layer. arranged circumferentially with respect to the tension member core, thereby modifying a surface texture of an outer surface of the blade connecting tension member. This reduces the drag as well as the noise originating from blade connecting tension members. Furthermore a tension member is disclosed.

A method for manufacturing a shell 36 and 38, is disclosed. The method includes laying one or more layers of fibres, on a surface of a mould 9 to form at least a portion of a shell half structure 36 and 38. A first panel 11 defined with noise reduction members 11a is positioned adjacent to the one or more layers of fibres on the surface of the mould 9. Further, resin is infused through the one or more layers of fiber and the first panel 11 and is subsequently cured to obtain the shell half structure 36 or 38, where the first panel 11 with noise reduction members 11a adheres to the shell half structure 36 and 38 upon curing the infused resin.

A method for reducing gear induced noise from a wind turbine is disclosed. A first vibration map and a second vibration map are generated, specifying, for each of a plurality of operating points of the generator, a virtual phase of vibrations originating from gear tooth meshing of the gearbox, relative to a first and second reference phase, at the respective operating points. An overlap between operating points of the first vibration map and operating points of the second vibration map is identified and virtual phases within the overlap are compared, thus deriving a phase offset between the first vibration map and the second vibration map. The virtual phase of vibrations of each of the operating points of the second vibration map are adjusted according to the phase offset, so as to align the first vibration map and the second vibration map, and the first vibration map and the second vibration map are combined into a resultant vibration map.

A method for reducing gear induced noise from a wind turbine is disclosed. A first vibration map and a second vibration map are generated, specifying, for each of a plurality of operating points of the generator, a virtual phase of vibrations originating from gear tooth meshing of the gearbox, relative to a first and second reference phase, at the respective operating points. An overlap between operating points of the first vibration map and operating points of the second vibration map is identified and virtual phases within the overlap are compared, thus deriving a phase offset between the first vibration map and the second vibration map. The virtual phase of vibrations of each of the operating points of the second vibration map are adjusted according to the phase offset, so as to align the first vibration map and the second vibration map, and the first vibration map and the second vibration map are combined into a resultant vibration map.

The present disclosure relates to a method of optimizing a rotor blade of a wind turbine, wherein said rotor blade extends from a rotor-blade coupling to a rotor-blade tip in a rotor-blade longitudinal direction with a rotor-blade length, having an aerodynamical profile extending between a leading edge and a trailing edge, wherein said method comprises the following steps: designing of said rotor blade for design environmental conditions including at least one design air density, with said designing comprising providing a sound-protection means, the sound protection means comprising at least one bristle, within a blade external region of said rotor blade the latter being defined as the 50% of said rotor-blade length abutting said rotor-blade tip; providing an air density at the installation site of said wind turbine; comparing said air density with said design air density; and increasing the induction factor by increasing a density factor of said sound-protection means when said air density is lower than said design air density.