The effect of blade-tower interaction on the structure loading of multi megawatt horizontal axis wind turbine

The aim of this work is to investigate the blade-tower interaction of multi megawatts upwind horizontal axis wind turbine (HAWT). With the increasing of the tower height, tower base becomes bigger and transportation problems appear. Nowadays, the tower dimensions are almost reached roads limits. To optimize tower dimensions there is the need to get a better understanding of what loads act on the tower. In this work, a CFD simulation of a 3MW upwind HAWT is performed to predict tower load for nominal operation conditions considering blade-tower interaction. It was found that blade-tower interaction induces significant dynamic load. The tower suffers pressure fluctuation called 3P oscillation (for three blades rotor) leading to cyclic fatigue and influences rotor stability. Moreover, because of blade passage in front of the tower, the stagnation point position changes and displacement of separation points on tower sides occur. The tower suffers different shedding frequencies on the upper and lower parts and side forces are resulted.