Power enhancement and energy efficiency of a wind turbine equipped with a slotted jet: 3D-DDES numerical simulations of the S809 airfoil

Renewable energy sources are increasingly meeting global energy demands, with solar power leading the way and being closely followed by wind energy. For this reason, scientific research is focused on finding new ways to maximise the power generated by wind turbines, utilising both passive and active circulation control devices. This paper aims to investigate the aerodynamic performance of the NREL Phase VI wind turbine using the blade element momentum (BEM) theory and computational fluid dynamics (CFD). The baseline configuration, consisting of an S809 airfoil, is modified to employ trailing edge blowing technology, an active circulation control technique known as Coanda Jet. Calculations are performed via 3D Delayed Detached Eddy Simulation (DDES) to solve the three-dimensional flow structures over the airfoil correctly. Variations in chord and twist angle along the blade’s radius are taken into account by analysing five distinct radial positions and, by using Blade Element Momentum (BEM) theory, the total power output generated by the wind turbine is calculated. Simulations are performed at a fixed absolute wind speed equal to 7 m/s, both with and without jet blowing, employing three different jet momentum coefficients Cμ to evaluate the improvements in the examined sections' aerodynamic performance and assess the energy efficiency of the used technology. Results indicate a notable increase in lift, which consequently enhances both torque and thrust, leading to a net power gain of up to 25.1% compared to the baseline case.