WELLS TURBINES WITH 3-DIMENSIONAL BLADES: THE PERFORMANCE UNDER UNSTEADY FLOW CONDITIONS

摘要

The effect of the 3-dimentional (3D) blade on the turbine characteristics of Wells turbines for wave energy conversion has been investigated numerically by a quasi-steady analysis under unsteady flow conditions in this study in order to improve the peak mean efficiency characteristics. The aim of use of the 3D blade is to prevent flow separation on the suction surface near the tip. The chord length is constant in the radius and the blade profile changes gradually from the mean radius to the tip. The proposed blade profiles in the study are NACA0015 from the hub to mean radius and NACA0025 at the tip. The performance of the Wells turbine with 3D blades has been compared with those of the original Wells turbine, i.e., the turbine with 2-dimentional blades. As a result, it was concluded that although the peak mean efficiency of a Wells turbine can be improved by the use of the proposed 3D blade, its blade does not overcome the stall characteristic.