A numerical investigation on the effect of blade tip shapes on power generation of a horizontal axis wind turbine

A way to increase the generated power of an available wind turbine blade without changing its base shape is to add proper add-on to the blade tip. In this paper, seven tip add-ons are added to the blade tip of the NREL Phase VI wind turbine, and their effect on generated power is studied using computational fluid dynamics. Reynolds averaged Navier-Stokes equations are used with k-ω SST turbulence model to simulate the flow over the blade. Results show that the tapered tip add-on does not have a notable effect on generated power, while the shark-tip add-on increases the output power by about 4%, which is a minor increase comparing to the other add-ons. The suction surface and pressure surface winglets (without sweepback) increase the power generated by 5.23% and 9.6% respectively, which shows the superiority of pressure surface winglet over suction counterpart. Afterwards, sweepback is added to winglets, showing 11.87% and 13.25% power increase for suction surface and pressure surface winglets respectively, which shows the positive effect of sweepback angle in generated power increase. This is obtained by only a 28 cm add-on to the base blade with a radius of 553 cm.