| Floating offshore wind turbines(FOWT) is the most protential wind power technology. Considering the electric energy production and cost, FOWT is usually designed as 5-20 MW wind turbines with longer blade and larger wind loads. The environmental loads of the FOWT are more complex than onshore, and the floating movement of the wind turbine platform is significant to aerodynamic load due to the interaction of the wind flow and the blade position. Taken the NREL 5MW wind turbine blade as the research object, the aerodynamic load calculation and the corresponding deformation are studied in this dissertation.(1) Based on blade-momentum theory, the aerodynamic load calculation model of the wind turbine blade is established considering the three-dimensional rotational effect, Prandtl and Glauert three correction methods, and the impeller thrust and torque are obtained by programming. The wind inflow velocity of the blade in the radial direction is changed because of the six degree of freedom movement of the floating platform. Considering these movement, the aerodynamic load calculation model is established, consequently the effect of the movement on the aerodynamic performance of the blade is researched. The results show that the pitch movement has the biggest impact on the aerodynamic performance of the blade. The calculated aerodyanmic loads are used to the static analysis of the blade with the finite element method.(2) NREL 5 MW wind turbine blade is composed of several types of airfoil profile for good aerodynamic performance. The three-dimensional entity model of the blade is built by adopting the parametric modeling method, and the finite element model is obtained with Shell 181. The tip deformation of the blade and the stress distribution are computed under the aerodynamic loads, and the relationship between the deformation and the thickness of the shear web. The analysis results are significant to the design, optimization and strength check of the blade. |
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