Turbine blade with auxiliary deflector

A fluid flow turbine blade assembly comprising:

• a rotor blade comprising a root section at which the rotor blade is attached to a hub of a fluid flow turbine and a working section, wherein the working section has a leading edge and a trailing edge and wherein the working section is configured and oriented to form a pressure surface facing oncoming fluid flow impinging on the rotor blade and a suction surface;
• and
• a deflector coupled to the rotor blade and extending spanwise along at least a portion of the working section of the rotor blade, wherein the deflector has a leading edge, a trailing edge, an upstream surface facing the oncoming fluid flow, and a downstream surface facing away from the oncoming fluid flow, wherein at least a portion of a chord extending between the leading edge of the deflector and the trailing edge of the deflector is disposed outside a profile of the deflector defined between the upstream surface of the deflector and the downstream surface of the deflector, wherein at least a portion of the upstream surface along at least a portion of a span of the deflector has a concave shape in a chordwise direction, wherein the deflector is spaced-apart from the rotor blade to form a gap between the deflector and the rotor blade along at least a portion of the span of the deflector to permit fluid flow through the gap, wherein the gap between the deflector and the rotor blade varies across at least a portion of the span of the deflector, and wherein the trailing edge of the deflector is situated aft of the trailing edge of the working section relative to a direction of travel of the turbine blade assembly.