An ocean current turbine for converting water currents energy includes the following features: a main frame arranged to be immersed in a water current, wherein the main frame comprises a bow part towards the water current, endless rotation chains with plates arranged to being captured at the bow part and driven backward by the water current, wherein the rotation chain runs about and in driving engagement with one or more driven wheels that operates a generator, and port and starboard side frames that are continuously convex and extends from the bow section and back to a transverse wide stern that is narrower than the greatest distance between port and starboard side frames, wherein the rotation chains include a starboard and a port endless rotation chain with the plates, and a reversing mechanism arranged to turn each plate to catch the water current at the bow part, so that each plate is driven backwards along the starboard, respectively port side frame, to back at the rear end of the wide stern part, and where the turning mechanism turns each plate to a passive state where the plate does not substantially catches the water when plate is led forward again by the rotation chain in a shielded cavity between starboard and port side frames and extending to the bow part.

A wind turbine device may include four wings. A first wing may include a first leading edge and a first trailing edge, and a second wing may include a second leading edge a second trailing edge. The first and second leading edges may be positioned on opposite sides of the axis of rotation, the first and second trailing edges may be positioned on opposite sides of the axis of rotation, and the first and second leading edges may be positioned relatively further to the axis of rotation than the first and second trailing edges. A third wing may include a third leading edge and a third trailing edge, and a fourth wing may include a fourth leading edge and a fourth trailing edge. The third and fourth trailing edges may be each positioned proximate to the axis of rotation and positioned on opposite sides of the axis of rotation.

A centrifugal compressor impeller includes a plurality of blades on a front side that extend from a first axial side to an outer radial end of the impeller. The centrifugal impeller includes a back side having a nonlinear backwall. The backwall can include a flat area hear a bore of impeller, a flat area near a tip of the impeller, and a convex surface between the flat areas of the bore and the tip. In some forms the impeller further includes a concave surface between the convex surface and the tip to form an s-shape. A transition or inflection point can denote the change from convex to concave. The convex and/or concave surfaces can take any variety of forms such as constant radius sections and/or compound curves.

A vortex generator for a wind turbine blade to be mounted to a wind turbine blade includes: a platform portion to be mounted to a surface of the wind turbine blade; and at least one fin disposed upright on the platform portion. The platform portion has a cross section having a curved convex shape, at least along a blade spanwise direction of the wind turbine blade.

A heat dissipation fan including a hub and a plurality of heat dissipation blades is provided. The heat dissipation blades are arranged around the periphery of the hub. Each of the heat dissipation blades includes a curved surface body and a flow guiding portion. The curved surface body has a pressure bearing surface and a negative pressing surface opposite to the pressure bearing surface. The flow guiding portion is connected to the curved surface body. The flow guiding portion has a concave surface and a convex surface opposite to the concave surface, wherein the concave surface is recessed in the pressure bearing surface and the convex surface protrudes outward from the negative pressing surface.

A vertical-axis wind turbine (VAWT) comprising a plurality of convex blades axially-rotating about a vertical axis. A wind shield rotating axially around the blades shields the blades facing convexly into the wind on the windward side of the turbine, the shield adapted to redirect wind moving against the shield to a high pressure zone on the concave side of the turbine blades. The radial distance between blades may vary along the chord length of the shield.

A rotor blade for a wind power installation, which extends in a longitudinal direction with a profile course from a blade connector to a blade tip, wherein the profile course contains at least one profile, comprising: a suction side and a pressure side, a relative profile thickness of greater than 25%, a profile chord, which extends between a leading edge and a trailing edge of the profile and has a length which defines the profile depth, a mean line which extends at least partially below the profile chord, a convex region which extends on the suction side from the trailing edge, and a convex region which extends on the pressure side from the trailing edge, wherein the convex region on the pressure side defines a rounded transition region of the pressure side to the trailing edge.

Provided is a blade capable of efficiently utilizing low-velocity fluid. The blade includes a main wing component, the main wing component has a streamlined cross section, an outer profile of which forms a first airfoil, the blade further includes a head wing piece in form of a sheet, the head wing piece has an arc-shaped cross section with a convex surface at one side and a concave surface at the other side, the head wing piece is arranged obliquely above a leading-edge point of the main wing component with the concave surface of the head wing piece facing the main wing component and a first ventilation space is formed between the head wing piece and the main wing component. By improving the configuration of the wing pieces of the blade, Cp of the blade is improved, and the manufacture cost of the blade can be significantly reduced.

A fluid and wind turbine system suitable for horizontal or vertical axis applications comprising (i) blades radially spaced around a rotational axis attached to a shaft by mounting formations so that the length axis of the mounting formations are substantially parallel to the width axis of the blades which mounting formations suspend the blades from the rotational axis creating a passageway allowing the air flow to pass through the turbine and impart a unidirectional rotational force to the shaft at all times the blades are exposed to the air flow on both the windward and leeward sides of the rotational axis (ii) an air flow director which shields the rotating blades from the air flow for a portion of their 360-degree rotation.

Rotor blade assemblies for wind turbines are provided. A rotor blade assembly includes a rotor blade. In some embodiments, the rotor blade assembly further includes a surface feature configured on an exterior surface of the rotor blade, the surface feature having an exterior mounting surface. At least a portion of the exterior mounting surface has a contour in an uninstalled state that is different from a curvature of the exterior surface of the rotor blade at a mount location of the surface feature on the rotor blade. In other embodiments, the rotor blade assembly further includes a seal member surrounding at least a portion of a perimeter of the surface feature. The seal member contacts and provides a transition between the exterior surface and the surface feature.