Performance Improvement of Savonius-Type Hydrokinetic Turbine with Bucket Airfoil Profile

A new design to enhance the output power of a Savonius hydrokinetic turbine by using buckets with airfoil profile instead of a conventional semi-circular design is developed. Effects of different camber angles of buckets' airfoil at 105 degrees, 120 degrees, 130 degrees, and 140 degrees are investigated and compared with the conventional profile. In addition, the influence of varying the buckets' camber position of the airfoil is considered to determine the camber angle at the maximum output power. Accordingly, a two-dimensional, unsteady incompressible turbulent flow model is developed and numerically simulated. The predicted results from the simulations are validated using available measurements. Results show that a significant enhancement of maximum output power is obtained using the airfoil profile at all studied camber angles compared to the traditional Savonius turbine with a semicircular profile. Furthermore, using a camber angle of 140 degrees attains the highest output power compared to other designs. At a water current speed of 0.4 m/s, and the overlap ratio of 0.15, the maximum power coefficient is 0.193. However, for the conventional design with a semi-circular profile, the maximum attainable power coefficient is 0.1 at the same operating conditions. The current findings provide an alternate direction in utilizing Savonius turbines with bucket airfoil profiles.