A fluid dynamic body having a trailing edge with a pattern formed thereon, the pattern can include a plurality of smoothly surfaced adjacent members with respective interstices therebetween, wherein at least one of the interstices completely contains a porous barrier. In some embodiments, the porous barrier can obstruct fluid flow through the respective interstice between a first surface of the fluid dynamic body on a first side of the trailing edge and a second surface of the fluid dynamic body on a second side of the trailing edge. This helps to reduce noise produced at the trailing edge. In some embodiments, the fluid dynamic body is a wind turbine blade or an air-engine blade.

A gear assembly includes a primary shaft, a driving gear, a driven gear, a secondary shaft, and a key wherein the primary shaft and the driving gear define a keyway for housing the key. The primary shaft defines a lower region of the keyway while the driving gear defines an upper region of the keyway. The driving gear may be mounted on the primary shaft such that the upper region and the lower regions of the keyway are aligned with each other in order for the keyway to house the key. The driven gear may be mounted on the secondary shaft such that the driven gear may be in meshing engagement with the driven gear. The aforementioned keyway defines a peninsula in a center portion of the driving gear. The peninsula is configured to abut a key disposed within the keyway.

A vane body of a guide vane includes a leading edge, and a trailing edge which is located closer to a runner than the leading edge, when located radially outside the runner. A projection extending in a direction from the trailing edge toward the leading edge is provided on an internal-diameter side blade face of the vane body, at least in any one of one side area of the internal-diameter side blade face and the other side area thereof in an axial direction of a guide vane rotation shaft, the internal-diameter side blade face being disposed on a side of the runner. The projection has a projection rear end of an arcuate shape, which projection rear end is formed to extend along a rotation trajectory which is drawn by the trailing edge when the vane body is rotated about the guide vane rotation shaft.

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.

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.

A trailing edge of a serrated fan blade includes a notch array including first, second, and third notches in a row. The first notch and the second notch define a first serration therebetween, and the second notch and the third notch define a second serration therebetween. The second notch has a largest or a smallest depth among depths of the first to third notches, and the first and second serrations each have an asymmetrical shape.

Rotor blade for a wind turbine, including a main blade part (4) with a blade tip (8). The blade tip (8) results in a blade tip vortex downstream of the rotor blade (1) during operation. The blade tip (8) includes a vortex de-stabilizer (7) which is configured to de-stabilize the blade tip vortex during operation of the rotor blade (1). Furthermore, a wind turbine field including a plurality of wind turbines positioned in a grid. One or more wind turbines on a boundary of the predetermined grid (e.g. a front row of the grid) are provided with at least one such rotor blade (1).

The invention relates to a device for converting wind energy to at least mechanical energy, comprising a rotor with a number of rotor blades drivable rotatably about a rotation axis by wind and a duct disposed therearound, wherein a central axis of the duct substantially coincides with the rotation axis of the rotor, characterized by guide means disposed upstream of the rotor for guiding the wind in a substantially helical movement round the central axis during use of the device such that the wind is supplied in the substantially helical movement round the central axis to the rotor.

A blade is used in fluid and includes: a base member; and a coat layer that is formed on the base member, a plurality of first grooves and a plurality of second grooves are formed on a surface of the coat layer, a pitch of the plurality of first grooves is different from a pitch of the plurality of second grooves.