Numerical study of trailing edge flow control for horizontal axis wind turbines

Wind turbines have been developed for more than a century and nowadays wind turbines are still facing some challenges such as efficiency and maintenance problems. Load control is considered to be one of the most important parts for future horizontal axis wind turbine (HAWT) designs. Deploying effective flow control devices on the blades could either increase loads at off-design wind speed conditions or reduce the extreme loads, leading to either higher energy output or a more stable energy output from the wind turbine. This study reports a research into the performance of trailing edge flow control devices of HAWT by solving the Reynolds averaged Navier-Stokes equations. The validation case selected for this work is the NREL Phase VI blade with experimental data. The trailing edge flow control devices studied include microtabs and microjets installed near the trailing edge of the rotating blade. The divergent trailing edge is also included in the study as a passive flow control device due to its practical interest. These trailing edge devices are implemented on the fixed-pitch NREL Phase VI blade, using the original performance and flow characteristics as a benchmark. Both 2D and 3D simulations are carried out in order to investigate the suitability of the 2D blade sectional design analysis and control for the actual 3D rotating framework. Moreover, the study is extended to an active pitch-regulated offshore wind turbine, NREW 5MW wind turbine. Firstly the code to code comparison is carried out for validation purpose. Then the trailing edge flow control devices are also deployed on this wind turbine to find out their effectiveness. The results show there are significant differences when compared to the conclusions from the CFD study on the NREL Phase VI blade

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