Performance assessment of a modified wells turbine using an integrated casing groove and Gurney flap design for wave energy conversion

The present study investigates the effect of a triangular casing groove depth and width on Wells turbine performance. Furthermore, it presents an integrated method to boost the power produced by the Wells turbine and delay the stall. This integrated method is implemented by combining the effect of the triangular casing groove with a rectangular Gurney flap (GF). The Gurney flap (GF) increases the lift coefficient by modifying the Kutta condition at the trailing edge. At the same time, the triangular casing groove improves the flow near the blade tip, leading to a delay in the stall inception. The Wells turbine performance is evaluated by solving numerically 3D incompressible Reynolds-Averaged Navier-Stokes equations. To solve the flow characteristics through the turbine, an SST k-ω turbulence model is used, which is validated and verified using previous experimental and numerical works. The results proved that the Wells turbine average torque coefficient increased by 81.11% when using a triangular casing groove and a rectangular Gurney flap. Moreover, the stall inception is delayed from a flow coefficient of 0.225–0.350, which increases the operating range by 55.50% and reduces the maximum efficiency compared with the conventional Wells turbine.