A Method to Calculate the Loads of Wind Turbine Blades and Researches of Adaptive Blades
Date Issued
2010
Date
2010
Author(s)
Lai, Wei-Ming
Abstract
Typically, analyzations of wind turbine blades are completed by using the finite element method with shells. Despite huge processing time consumed, the finite element method is convenient in calculating blade structures based on the advance of modern calculators. When the coupling between fluid and the blade structures are considered, either the global finite element simulation or that together with the CFD simulation is often adopted; however, this kind of method accompanying increasing processing quantity tends to be time-consuming and inefficient. Thus, the article uses a combined analytical and finite element beam to not only solve the foregoing problem, but consider the interaction between fluid and the blade structures. Besides, the analytical method adopted in the article help find out the sectional properties of the blades, which are important information to blade designers yet is not able to acquire by using the finite element method with shells. In addition, the present method can also reduce processing time to a great extent comparing to the finite element method with shells. Further, the method allows easy means for modifying the parameters during simulations. In the verification models of the article, the errors between present method and pure finite element method with shells by ABAQUS are mostly less than 10%. Therefore, there is no doubt about the accuracy of the calculation results. With the advantages described above, the present method in the article is suitable to be a reference in the design of the wind turbine blades.
The article also analyzes the elastic coupling blades, of which discussions on the applicability are meanwhile elaborated. The baseline blade model adopted in the article is SERI-8 developed by NREL. Moreover, two elastic coupling blades—the bend-twist coupling blade and the extension-twist coupling blade—are tested by changing the fiber orientation angle to achieve the elastic coupling property. The bend-twist coupling blade is triggered by the thrust force generated by fluid, and is expected to twist the pitch angle like a passive controller. Considering the calculated results in the article, the twist angle of the bend-twist coupling blade is too small to be a fine passive controller of the wind turbines. On the other hand, the extension-twist coupling blade is triggered by the centrifugal force, but the results are worse than that of the bend-twist coupling blade. As for the mechanical behavior of materials, the stress of the coupling blades is a little higher as predicted than that of the baseline model.
Subjects
wind turbine
elastic coupling
fluid-structure coupling
blade
FEM
Type
thesis
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