This invention relates to a noise reducing device, a wind turbine blade comprises such a noise reducing device, a method of retrofitted a noise reducing device, and a method of manufacturing such a noise reducing device. The noise reducing device comprises first noise reducing elements projecting from a base part having a third surface towards a second end. Second noise reducing elements are attached to the third surface and projects along the first noise reducing elements towards the second end. The first noise reducing elements are preferably serrations while the second noise reducing elements are bristles. The bristles projects at least into the gaps formed between adjacent serrations.

The present invention relates to a wind turbine rotor blade assembly comprising a rotor blade and a noise reducer (70) configured on the rotor blade. The noise reducer (70) comprises a plurality of aligned spine members (72), each spine member having a length and comprising a first section (74) extending along a first part of the length of the spine member, and a second section (76) extending along a second part of the length of the spine member, wherein the first section (74) has a higher stiffness than the second section (76).

A rotor blade for a wind turbine has a rotor blade root defining a reference plane for attachment to a hub. Adjacent to the rotor blade root is a profile region extending to the rotor blade tip. In the profile region, the rotor blade has a blade profile defining a chord. The chord angle between the reference plane and the chord increases over the entire profile region, from the rotor blade root towards the rotor blade tip.

The present invention relates to a wind turbine blade (10) with an access window (94) extending through a shell body of the blade. A frame (96), which defines an opening (97), is arranged on top of the outer surface of the blade such that the opening of the frame (96) is aligned with the access window. A cover member (92) covers the opening (97) of the frame and releasably closes the access window.

The present disclosure relates to devices (350) for reducing vibrations in wind turbines (10) and to methods (450) for using the devices (350) and mitigating wind turbine vibrations. More particularly, the present disclosure relates to devices (350) for reducing vortex induced vibrations and stall induced vibrations when the wind turbine (10) is parked, especially during wind turbine installation and/or maintenance, and to ways in which the devices (350) can be used, e.g. for installing them on wind turbine blades (22) or once they are already installed thereon. A vibration mitigating device (350) for mitigating vibrations of a parked wind turbine (10) is provided. The device (350) is configured to be arranged with a wind turbine blade (22). The device (350) comprises one or more air flow modifying elements (330). At least one of the air flow modifying elements (330) is configured to change between a retracted configuration (370) and an extended configuration (375).

The present disclosure relates to devices (300) for wind turbine blades (22) and methods for reducing vibrations in wind turbines (10). More particularly, the present disclosure relates to devices (300) for mitigating vortex induced vibrations and stall induced vibrations, wind turbine blades (22) comprising such devices (300), and methods for reducing wind turbine vibrations when the wind turbine (10) is parked, especially during wind turbine installation and/or maintenance. A device (300) comprises a proximal support (310) configured to be arranged around a first portion (221) of a wind turbine blade (22), a distal support (320) configured to be arranged around a second portion (222) of the wind turbine blade (22), and a barrier (330) extending between the proximal support (310) and the distal support (320). The first portion (221) of the wind turbine blade (22) is at a different longitudinal position along the blade (22) than the second portion (222). The proximal (310) and distal (320) supports are configured to provide a gap (350) between the barrier (330) and a wind turbine blade surface.

The present disclosure relates to devices (300) for wind turbine blades (22) and methods (400) for reducing vibrations in wind turbines (10). More particularly, the present disclosure relates to devices (300) for mitigating vortex induced vibrations and stall induced vibrations, wind turbine blades (22) comprising such devices (300), and methods (400) for reducing wind turbine vibrations when the wind turbine (10) is parked, especially during wind turbine installation and/or maintenance. A device (300) is configured to be arranged around a wind turbine blade (22) and comprises three or more air flow modifying elements (305) comprising a concave outer surface (323) configured to face away from a wind turbine blade (22). The device further comprises a supporting structure (310) configured to support the plurality of air flow modifying elements (305). An angular distance (307) between adjacent air flow modifying elements (305) in cross-section is substantially constant.

A method of controlling a wind turbine, wherein the wind turbine includes a hub having at least one blade with at least one an add-on member which is actuated to alter aerodynamic properties of the blade. The method includes a step of acquiring a target noise level, and a step of controlling the at least one add-on member of the blade such that an actual noise level caused by the operation of the wind turbine is equal to or below the target noise level.

An airflow guiding device for the sound- and pressure-optimized supply of an airflow to an inlet nozzle of a fan, in particular a radial fan, wherein the inlet nozzle has a nozzle input opening with an incident flow angle, the airflow guiding device having: a frame device which extends along a longitudinal axis in an axial direction with a height between an inlet opening, through which the airflow flows into the frame device in an operating state, and an outlet opening, through which the airflow flows out of the frame device in the operating state, wherein the inlet opening has an inlet cross section with a minimum inlet cross-sectional width, and the outlet opening has an outlet cross section with a minimum outlet cross-sectional width which corresponds to the minimum inlet cross-sectional width or which is smaller than the minimum inlet cross-sectional width, and the frame device comprises a flow duct which connects the inlet opening and the outlet opening in terms of flow, wherein the outlet opening is configured to be connected in terms of flow to the inlet nozzle of the fan in the operating state, characterized in that the height of the frame device according to the following formula h≥(D−d)/(2.Math.tan(β)) corresponds to a ratio of a difference of the minimum inlet cross-sectional width and a diameter of the inlet nozzle and double the value of the tangent of the incident flow angle or is greater than the ratio, and a grid element, which is arranged on the inlet opening.

The invention relates to a wind turbine blade oscillation preventer comprising an aperture and a sleeve and having a peripheral extent and a longitudinal extent, the preventer being configured for removable application over a wind turbine blade and configured to extend longitudinally thereover and peripherally thereabout; the preventer having a non-aerodynamic exterior surface which exhibits a rough surface capable of disrupting smooth or laminar airflow over a substantial portion of the longitudinal and peripheral extent of the sleeve when the preventer is in place on a wind turbine blade. The preventer further comprises a smooth interior surface extending along a substantial portion of the longitudinal extent of the sleeve. The invention also relates to a method of application of a blade oscillation preventer over wind turbine blades which comprise serrations at a trailing edge thereof.