Development and performance evaluation of stall delay bi-directional air turbine with additional blades

Abstract

In this study, we aim to solve the problem of the stall phenomenon on Wells turbines by attaching additional blades to both sides of the rotor surface of Wells turbine. With this new turbine concept, a highly efficient and inexpensive stall delay turbine that can achieve stable efficiency over a wide range of rotation speed. In this abstract, The airfoil and rotor design of the turbine was done using RANS simulation using k - ω SST model. First, a CFD analysis is carried out for a conventional Wells turbine in order to understand the flow field under stall and non-stall region. Based on this result, the blade shape which prevents the torque reduction in the stall region was obtained by two-dimensional analysis and optimization of the turbine cascade. Then three-dimensional turbine performance was evaluated based on the optimized two-dimensional shape. Moreover, we improved the design of the turbine considering three dimensional effects by changing the height of the additional blade and changing the radial distribution of the blade solidity. The turbine is tested at the real sea test site of OWC plant and compared with traditional Wells turbine.