Three-dimensional effects of trailing edge flap and winglet integrated on up-scale wind turbine blade

Abstract

Wind turbines must generate wind power cost-effectively for the wind power to remain viable and competitive among other renewable resources. The rotor diameter continues increasing in size to capture more energy to reduce the costs of wind power. However, the size of the rotor diameter is expected to reach limit due to restrictions related to the rotation of the entire blades, transport, and installation issues. This study, therefore, seeks to compare the effects of trailing edge flap and winglet embedded on the up-scale wind turbine blade. The investigated configurations are blade with winglet, blade with trailing edge flap and blade with a combination of the winglet and trailing edge flap. A straight blade of the NREL 5MW wind turbine was used as a benchmark to quantify effects of trailing edge flap and winglet. All simulations were performed using the ANSYS FLUENT. The steady pressure-based solver in absolute velocity formulation modelled the flow over the blade surfaces governed by Reynold-Averaged Navier-Stokes (RANS) equations closed with the k – ω SST turbulence model. Blades with trailing edge flap and combined trailing edge flap and winglet show similar effects in comparison of pressure coefficient at 0.32R, 0.60R and 0.92R. Blade with a winglet generates the highest aerodynamic torque, while blade with trailing edge flap decrease most of the flap-wise bending moment. The blade with combined trailing edge flap and winglet can serve as an alternative design for improving the wind turbine performance. That is, at the normal operating condition the trailing edge flap can be held at its neutral position whenever increment of the power is the primary target.