Hydrodynamic Performance and Flow Field Characteristics of Tidal Current Energy Turbine with and without Winglets

Abstract

In order to gain a more comprehensive understanding of the influence of winglets on the hydrodynamic performance and flow field characteristics of tidal current energy turbines, two different shapes of winglets are designed, and numerical simulation results for turbines with and without winglets are compared and analyzed. The results show that both shapes of winglets can improve the energy conversion efficiency, and the winglets with a cant angle (60°) are more effective than the flat (0°) winglets; the winglets transfer the tip vortices to the winglet tips and weaken the tip vortices, increase the pressure coefficients of the cross-section in the tip region, and inhibit the three-dimensional flow phenomenon in the tip region; the winglets will make the wake axial velocity deficit larger in the near-wake region, and with the axial distance increases, the axial velocity of the wake flow with winglets recovers faster than that without winglets; winglets can make the vortex pairing and breaking of the turbine tip vortex faster, which can also be observed by the change in the turbulent kinetic energy (TKE).

Performance Improvement of a Straight-Bladed Darrieus Hydrokinetic Turbine through Enhanced Winglet Designs

“…The results showed that at the optimum point, a 7% increase in the power generated by the turbine is achieved and that the optimum corresponds to a pitch angle of 33.2 • and a winglet height of 2.04% of the turbine radius. Wang et al [13] evaluated the influence two winglet designs in the performance of a horizontal tidal turbine, obtaining increases of 19% and 26% at the design tip speed ratio of 5. Malla et al [14] performed simulations on a Darrieus-type wind turbine studying the influence of the radius of curvature and the height of an asymmetric winglet on the turbine performance.…”