Taguchi Modified Additive Model for Aerodynamic Optimization of Wind Turbine Blade Trailing-Edge Serrations

The present work employs a statistical-numerical method to predict and optimize the shape of the serrations for maximum aerodynamic improvement. A long-term objective for the rotor is to achieve relatively high aerodynamic performance in particular wind conditions. Inspired by the remarkable flight characteristics of owls, an optimal trailing edge serration design is investigated and proposed for a wind turbine rotor blade. Fluid flow interaction with the proposed serrations is explored for different wind conditions. A potential solution to improve existing wind turbines is the addition of flow-control devices to the rotor blades. Flow control devices can effectively prevent or delay flow separation and suppress turbulence resulting in improved aerodynamic and aeroacoustics performance, load reduction, fluctuation suppression, and ultimately increased wind turbine power output. The result is supported by subsequent validation with three-dimensional numerical tools. The optimal combination is found using the Taguchi design of experiment with three factors: Amplitude, wavelength, and serration thickness. The viability of the solution on an application is assessed using the Weibull distribution of wind in three selected regions. Results show that the presence of serration is capable of improving the annual power generation in all the investigated cities by up to 12%. The rated speed is also shifted from 10 m/s to 8m/s for most configurations. Additionally, all configurations show similar trends for the instantaneous torque where an increase is observed in pre-rated speed whereas a decrease is noticed in the post-rated speed region. A look at the flow field pattern for the optimal design in comparison with the clean blade shows that the modified blade is able to generate more lift in the pre-stall region, while for the post-stall region, early separation and increased wake dominate the flow. Further studies in this area can cover the mechanical aspect and aero-acoustic impact of the trailing edge serrations as well as the correlation between acoustic emission, power generation, and aerodynamic forces in the improvement of an overall wind turbine performance.