On the use of vortex generators to improve tidal turbine performance

Vortex Generators (VGs) are a passive flow control device with multiple applications, including horizontal axis wind turbines (HAWT). Their most popular version is that of thin vanes protruding normal to the blade surface, at an angle to the oncoming flow. Despite their popularity and success in the more established wind turbine industry there has been very little application of VGs on tidal turbines. The present investigation builds on the success of VGs on HAWTs and attempts to examine their effect on a tidal turbine. A numerical VG parametric study is performed on two hydrofoil profiles of different thickness, 30% and 20%. An in-house Reynolds Averaged Navier Stokes solver (MaPFlow) is used for this part of the study. The best performing VG configurations are selected and their effect on the profiles’ lift and drag polars are used to predict the effect on the tidal turbine performance. This is evaluated using an in-house Blade Element Momentum code. Results are very promising and indicate that the use of VGs could significantly improve the performance of tidal turbines over a range of tip speed ratios. Future work includes wind tunnel tests to further validate the present simulations, blade resolved RANS analysis of the turbine blade and high-fidelity simulations to analyse the VG effect on the boundary layer flow.