The narrow operating range of a Wells turbine restricts its energy extraction capability from the ocean waves. In this work, the concept of a radiused edge tip blade (RETB) was introduced to overcome such an issue. The RET modifies the tip and changes the tip leakage flow behaviour. The flow through the turbine annulus was simulated numerically and compared with the existing experimental results of the reference turbine. Three-dimensional Reynolds-averaged Navier–Stokes equations with a two-equation turbulence closure model available in ANSYS CFX 14.5 was used for the simulations. The computational domain was discretized with unstructured tetrahedral elements, and the grid independence study gave an optimal grid. The RETB altered the tip leakage flow characteristics and delayed the stall inception. The RETB enhanced the relative operating range by 25% and peak torque by 37%. © 2021, King Fahd University of Petroleum & Minerals.