Patent ID: 7744338

Claim:
A fluid turbine system, comprising: a turbine comprising blades rotatable about an axis, each of the blades comprising a generally straight front surface portion spaced from the axis, a hook portion extending outwardly from the straight front surface portion, a curved rear surface portion that is rearward of and curved relative to the straight front surface portion, and a window that occupies a substantial portion of a height of the blades and is positioned closer to the axis than the straight front surface portion, wherein a first plane parallel with and intersecting the axis divides the space surrounding the turbine into a return side and a push side opposite the return side, the turbine configured to rotate generally in an upstream direction on the return side and generally in a downstream direction on the push side relative to a fluid flowing nominally parallel to the plane; and a concentrator positionable in a concentrator position upstream of at least a portion of the turbine and at least partially or completely on the return side, the concentrator having the shape of a leading end of an airfoil or a parabola and comprising a first curved surface portion configured to extend from a first position upstream of the turbine to a second position further upstream of the turbine and further into the return side, wherein the first curved surface portion is configured to be convex facing an upstream direction of the fluid flow; wherein the first curved surface portion deflects at least some fluid toward the push side and creates a relative vacuum to draw at least some fluid away from the window of the blades in the concentrator position, the concentrator movable toward a blocking position further toward the push half relative to the concentrator position such that the concentrator blocks some fluid from reaching the push half of the turbine.