A hydrokinetic turbine, operative in a water environment and driven by a water current, the turbine comprising:
- upper and lower vane mounts;
- a main shaft coupling the vane mounts to form an assembly and defining a central axis;
- the assembly being mounted for rotation about the central axis, the main shaft providing a rotational output;
- a set of at least three vanes, each vane having a longitudinal axis and mounted between the upper and lower vane mounts for reciprocating rotation about its respective longitudinal axis, each of the vanes having a drive mode when, in the course of rotation of the main shaft, in a first rotational segment, water current causes such vane to drive the main shaft and, in a second rotational segment, water current causes such vane to be driven by the main shaft;
- a vane angle control mechanism, configured to control angle of the vanes relative to the direction of current so as to provide an angle of attack, relative to the direction of the current, that is cyclically adjusted over the course of rotation of the shaft;
- wherein the vane angle control mechanism operates so that a given vane of the set of vanes is oriented:
- (i) substantially transversely to the direction of the current when the assembly's orientation causes the given vane of the set of vanes to be in a driving mode, to power rotation of the assembly over the first rotational segment of the assembly, wherein substantially transverse to the direction of the current is defined as having an orientation in which the direction of the current is less than 45 degrees of a normal to a face of the given vane on a working side of the vane, and
- (ii) substantially parallel to the direction of the current when the assembly's orientation causes the given vane of the set of vanes to be in a driven mode over the second rotational segment, to return the given vane of the set of vanes to a rotational position at a beginning of the first rotational segment, wherein substantially parallel to the direction of the current is defined as having an orientation in which the direction of the current is greater than 45 degrees of the normal to the face of the given vane on its working side,
- wherein the vane angle control mechanism includes:
- a set of control cam segments located along the first and second rotational segments mounted in a location selected from the group consisting of above the upper vane mount and below the lower vane mount, each cam segment forming a curved cam groove;
- and
- a set of guide wheels, each guide wheel associated with a distinct one of the vanes and mounted so that a center of the guide wheel coincides with the longitudinal axis of the corresponding vane, each guide wheel including a set of follower rollers disposed over a rotational extent of at least 45 degrees around such guide wheel and engageable with a corresponding one of the grooves, depending on an angular position of the assembly, wherein engagement of a given follower roller of the set of follower rollers of a given guide wheel of the set of guide wheels in a groove of a given cam segment of the set of cam segments establishes angular orientation of the corresponding vane over the duration of such engagement.