Turbines are used to harness power from water flow by using the water flow to move a turbine rotor and generate power. Turbine blades are traditionally straight blades that extend perpendicular to the central axis of the turbine. Turbines can be uses to generate power from wind or water movement such as current and tidal flow.
There are many different blade shapes and profiles presently in use but not all blades perform in the same manner in differing turbine applications. For marine turbines, technology developed for wind power generation has typically been adopted. As seawater is much denser than air, there are opportunities to generate significantly more power from marine turbines.
With a straight blade, since the velocity of the blade tip is much greater than that of the blade root, as fluid flows over the blade, the distribution of force applied to the blade can vary significantly from the blade root to the blade tip. This inhibits the efficiency of the blade resulting in less than optimal power generation from a given fluid flow.
For these and other reasons, known central axis water turbines do not provide optimum usable power output in typical water flow conditions.
The present invention seeks to ameliorate one or more of the abovementioned disadvantages.