The double-regulated turbine comprises a spherical hub, adapted to rotate around a first rotation axis, and blades, which are each able to be swivelled relative to the hub around a second rotation axis, transversal to the first rotation axis, by respective coupling flanges that are mounted fixedly on the spherical hub and that include each an attachment surface for a corresponding blade. The attachment surface of the coupling flanges includes a flat portion.

A runner for a hydraulic turbine, including a hub and a plurality of pivotable blades extending from the hub. Each pivotable blade of the plurality of pivotable blades includes a root located at the hub, a tip opposite the root, and a leading edge. Each pivotable blade of the plurality of pivotable blades is pivotable relative to the hub about a respective pivot axis. For at least one blade, the leading edge at the root is positioned along a radial axis of the runner and the leading edge at the tip is cantilevered beyond the radial axis in a circumferential direction of the runner.

The lengths and/or chords and/or pitches of wind turbine or propeller blades are individually established, so that a first blade can have a length/chord/pitch that is different at a given time to the length/chord/pitch of a second blade to optimize performance and/or to equalize stresses on the system.