Axial flow turbine apparatus

An axial flow turbine apparatus for deployment in a waterway, the turbine apparatus comprising:

• a rotor support system;
• a rotor mechanism;
• and
• a power take-off device;
• wherein the rotor support system is operable to support and control position and alignment of the rotor mechanism relative to a direction of flow of flowing water in the waterway, wherein deployment of the turbine apparatus in flowing water generates power;
• wherein the rotor support system includes:
• an elongated shaft having an internal surface;
• a buoyancy adjusting component;
• a flexible coupling at a first end of the elongated shaft;
• and
• the rotor mechanism being attachable to a second free end of the elongated shaft;
• wherein the flexible coupling:
• facilitates connection of the first end of the elongated shaft to a support structure located in the waterway in which the turbine apparatus is deployed, and facilitates a substantially freely yawing connection of the axial flow turbine apparatus to the support structure located in the waterway in which the turbine apparatus is deployed;
• controls pitching and yawing motion of the elongated shaft and the rotor mechanism relative to the support structure;
• and
• in use, responds to changes in flow of the flowing water, to maintain the turbine apparatus with a compliant attitude, thereby maintaining alignment of the axis of the elongated shaft and the rotor mechanism with the direction of flow;
• and
• wherein the buoyancy adjusting component is operable to maintain the deployed turbine apparatus with substantially neutral buoyancy relative to the waterway in which the turbine apparatus is deployed,
• wherein the buoyancy adjusting component comprises a movable mass that is movable relative to the elongated shaft to adjust buoyancy distribution of the assembly of the elongated shaft and the rotor mechanism such that the position of the rotor mechanism relative to the body of water is neutrally buoyant or buoyantly stable,
• wherein the buoyancy adjusting component is a shaft-based buoyancy aid that is located within the elongated shaft, the movable mass being connected to the internal surface of the elongated shaft, the movable mass being located inside a sealed gas-filled buoyant tube, wherein the gas-filled buoyant tube is sealed at both ends.