A method is provided for forming an add-on component for an aerofoil which enable the structure of the aerofoil to be tuned in order to reduce the amplitude of sound produced at frequency f.sub.peak when air flows in a flow direction from the leading edge over the trailing edge of an aerofoil. The method applies both to add-on components having a slitted formation and a Double-Rooted Trailing Edge Serration (abbreviated to “DRooTES”).

To provide a wind power generation device that can be suitably increased in size while increasing the electricity generation efficiency. A wind power generation device (10) is characterized by being provided with: a first wind turbine unit (12) comprising multiple wind turbines (30a to 30d) aligned in one line; a pair of blade units (16), each of the blade units being disposed adjacent to the first wind turbine unit (12) and having an inner-side shape extending along the circumferences of circles defined by rotation of the wind turbines (30a to 30d) to enhance collection of wind by the rotation; and a conversion unit for converting energy obtained by the rotation of the first wind turbine unit (12) to electricity.

A wind turbine blade (10) is described having a serrated trailing edge (20). Splitter plates (106) are provided on the blade, to reduce operational noise. Each splitter plate (106) is arranged to extend at least partly into a space in between adjacent serrations. The splitter plates can be formed integrally with the serrations, or attached to existing serrations as a retrofit solution. The serrations with the splitter plates can be provided as a trailing edge panel (108) for attachment to the trailing edge of an existing wind turbine blade.

The present invention relates to a wind turbine blade (10) comprising two or more serrations (100a, 100b, 100c) provided along a section (S) of the trailing edge (20). The section (S) extends spanwise from the tip end (14) towards the root end (16) for up to 5% of the total blade length (L), The serration (100a) closest to the tip end has a height (H) and/or width (W) greater than the respective height (H) and/or width (W) of at least one other serration (100b, 100c) in said section. The present invention also relates to a wind turbine (2) comprising at least one wind turbine blade (10) of the present invention and to a serrated panel (66).

A rotor blade for a wind turbine, wherein the rotor blade includes serrations along at least a portion of the trailing edge section of the rotor blade is provided. The serrations include a first tooth and at least a second tooth, wherein the first tooth is spaced apart from the second tooth. Furthermore, the area between the first tooth and the second tooth is at least partially filled with a plurality of comb elements, wherein the comb elements are arranged substantially parallel to each other and in substantially chordwise direction of the rotor blade such that generation of noise in the trailing edge section of the rotor blade is reduced. The rotor blade is further characterized in that it includes a plurality of ridges including a first ridge and at least a second ridge for manipulating an airflow which is flowing along the ridges.

Provided is a trailing edge assembly of a wind turbine rotor blade, which includes a mounting portion; a flap portion flexibly connected to the mounting portion so that a flap angle subtended between the mounting portion and the flap portion can be altered; a volume adjustable chamber arranged between the mounting portion and the flap portion and realised to alter its volume between a minimum volume associated with a minimum flap angle and a maximum volume associated with a maximum flap angle; and at least one tube to face into an airflow passing over the airfoil region of the rotor blade, and an inner orifice arranged to face into the interior of the volume adjustable chamber such that an airflow between the outer orifice and the inner orifice alters the volume of the volume adjustable chamber. Embodiments of the invention further describe a wind turbine rotor blade.

A ducted fan is provided including a fan casing surrounding a plurality of fan blades mounted to a rotating drive shaft. The plurality of blades define a tip stagger angle of greater than 68 degrees and the fan casing defines an annular recess defined by an inner wall of the fan casing, the annular recess extending about the circumferential direction proximate a blade tip of each of the plurality of blades. The annular recess may define an average recess depth greater than 10 percent of the tip chord length. The annular recess may also define a length ratio equal to a recess length over the tip axial chord length that is greater than 1.5.

A wind turbine blade apparatus at least includes a wind turbine blade body, wherein a serration portion is disposed on at least on a part of a trailing edge of the wind turbine blade body, the serration portion having a saw-teeth shape where a mountain portion and a valley portion are arranged alternately in a blade longitudinal direction, and wherein a chord-directional cross section of the wind turbine blade body along a chord direction is formed to have an airfoil shape at any position in a region from the mountain portion to the valley portion.

A wind turbine rotor blade that has a rotor blade tip, a rotor blade root, a suction side, a pressure side, a rotor blade length, a profile depth and a pitch axis of rotation. The profile depth decreases along the rotor blade length from the rotor blade root to the rotor blade tip. The trailing edge has a trailing edge delimiting line, which replicates the contour of the trailing edge. The trailing edge has a plurality of serrations to improve flow behavior at the trailing edge. The serrations respectively have a serration tip, two serration edges and an angle bisector. The serration edges are provided non-parallel to a direction of incident flow that is perpendicular to the pitch axis of rotation. The serration edges are non-perpendicular to a tangent to the trailing edge delimiting line. The trailing edge delimiting line has a plurality of portions, at least one of the portions extending non-parallel to the pitch axis of rotation.

A serrated panel (70) for a wind turbine blade is disclosed. The panel (70) is configured to be attached to the trailing edge of a blade to form a plurality of serrations (71) at the trailing edge of the blade. The serrated panel comprises a base part (72) for attaching the panel (70) to the trailing edge of the blade. An exterior surface (78) of the base part comprises a corrugated surface in direction between longitudinal ends of the panel such that the exterior surface comprises crests (82) aligned substantially with midpoints of bases (80) of the serrations (71) and valleys (83) aligned substantially between serrations (71).