<p>A wind turbine for capturing energy from a fluid flow comprises a rotor having a rotational axis and a plurality of rotor blades (104) arranged for rotation about the rotational axis. The rotor blades extend longitudinally in a direction substantially parallel to the rotational axis. A shield member V3 is arranged to shield some of the rotor blades from an oncoming wind where incidence of the wind on those rotor blades would act against rotation of the rotor in the direction of rotation. The rotor blades (104) are distributed about the circumference of the rotor and are spaced from the rotational axis, defining a substantially cylindrical space within the rotor through which the wind passes. The shield member V3 is defined by a radially inward surface and a radially outward surface. The radially inward surface follows substantially a portion of the circumference of the rotor. The radially outward surface of the shield member V3 comprises a first portion which meets the radially inward surface. In the region of the interface with the radially inward surface, the first portion extends in a first direction n that makes an angle of at least 0 degrees and up to 90 degrees in the contra-rotational direction with the radial direction of the rotor. The radially outward surface of the shield member V3 comprises a second portion which meets the first portion. At least a portion of the second portion extends in a second direction p that makes an angle of more than 0 degrees in the contra-rotational direction with the first direction n. The turbine has improved power output and efficiency compared to earlier similar designs.</p>
