A vertical axis wind turbine with a symmetric airfoil having a concavely curved tail portion defining a trailing edge angle of between 0 and 5 on either side of the chord, a maximum thickness center point between 26% and 34% of the length of the chord from the leading edge, a leading edge curvature ratio (D1/D2) from 0.42 to 0.50, and a ratio of maximum thickness to chord length T/C from 0.12 to 0.19, preferably 0.16. Advantageously, the rotor may have helical blades defining a cylindrical swept envelope with a positive angle of attack and a solidity ratio NC/D from 0.125 to 0.270, and is governed at a tip speed ratio from 2.25 to 4.00.

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.

A hydrokinetic energy conversion system (1) comprising a turbine device (2) comprising a rotor (3) displaying a rotational axis (O), which turbine device is arranged to operate with the rotational axis in an inclined orientation vis--vis an incoming body of water (W), and which rotor comprises a blade (10) which is arranged to interact with the incoming body of water such that rotational energy is imparted to the rotor. The blade comprises a first, convex surface (12), a second, concave surface (13) and a free, distal edge (E) where the first surface and the second surface meet. The curvature of the second surface, when viewed in a plane orthogonal to the rotational axis, is such that a maximum depth (Dmax) of the second surface, when measured from a straight line intersecting the rotational axis and the distal edge, is at least 35% of the distance between the rotational axis and the distal edge.

Fan for ovens for cooking foods, which comprises: a support plate arranged substantially orthogonal to the rotation axis of the fan; and multiple blades projectingly fixed on the support plate and radially arranged around the rotation axis. Each blade of the fan is provided with an internal edge, which is shaped with a convex portion that is projectingly extended between a first and a second concavity of the internal edge itself.

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.

The application provides a wind power generation system. The application discloses one or several set of power generation units, which generate power by driving the power generation units through the airflow generated by the natural environment or the carrier device, and then the control module outputs the power to the power storage device, and then supplies power to each power-consuming equipment by the diverter connected to the power output terminal of the power storage device, respectively. The internal structure of a turbofan blade of this application has a cavity for repeated impact of airflow, which can utilize a single inlet air to generate several drives to the blades, so that tiny wind can provide more stable power supply for various power-consuming facilities, and the power generation system of this application is less affected by external environmental factors.