Abstract
Wave energy conversion devices incorporating the Oscillating Water Column (OWC) principle are the most extensively used wave energy converting technologies to date. In this paper, we explore the effect of a fixed blade Denniss-Auld turbine that is representative of the maximum pivot points which occur during OWC inhalation and exhalation. Whereas conventional Denniss-Auld turbines are mounted on an intricate hub system that allows for controlled blade rotation to optimize performance, we investigate the possibility of removing the mechanical complexity while maintaining good aerodynamic performance. The assessment of turbine performance is carried out using non-dimensional coefficients, i.e., torque, pressure drop, and efficiency. The simulations are completed by solving the incompressible, steady-state Reynolds Averaged Navier-Stokes (RANS) equations with the k-ω SST turbulence model using ANSYS™ CFX. Validation of our numerical approach was completed by comparing existing experimental and numerical data of a Wells turbine. Furthermore, a grid independence study was conducted to achieve accurate numerical results. Overall, the modified Denniss-Auld turbine does not stall at high flow coefficients and has an extended operating range similar to an impulse turbine; however, with a much lower maximum efficiency of 12%. Future work should explore a larger design space with blade optimization using parametric studies to improve device efficiency.
