Comprehensive and synergistic analysis of geometry effect on an axial turbine performance for wave energy conversion

Abstract

Wells turbine is very proficient in converting pneumatic power from ocean waves into mechanical energy. However, such turbines suffer from low performance, limited operating range, and low efficiency. The present study introduces an innovative design to enhance the power produced by the Wells turbine; by implementing different geometries of Gurney flap (GF). The Gurney flap is placed on both pressure and suction sides of the trailing edge (TE) and perpendicular to the chord line without changing chord length. GF alters the Kutta condition at the trailing edge TE, which increases the coefficient of lift. The performance of the Wells turbine is evaluated through solving numerically the 3D incompressible Reynolds Averaged Navier–Stokes equations (RANS) by using ANSYS Fluent. The performance is investigated according to the flow coefficient, total pressure drop coefficient, torque coefficient, and the turbine efficiency, as well as presenting the streamlines colored by velocity and pressure fields around the turbine blades to demonstrate the improvement of Wells turbine performance. The validation of the present work is achieved using previous experimental work and computational fluid dynamics (CFD) work by using the SST k−ω turbulence model. The present results show that the torque coefficient is increased by 41.98% compared with conventional Wells turbine using Gurney flap GF. Besides, the stall is slightly delayed compared with the Wells turbine without GF.