Structural design of spars for 100-m biplane wind turbine blades

TitleStructural design of spars for 100-m biplane wind turbine blades
Publication TypePresentation
Year of Publication2012
AuthorsJohnson, Perry M., and Richard E. Wirz
Keywordsbeam finite elements, biplane spar, cross-sectional analysis, structures, wind turbine blades
AbstractAs wind turbines grow larger, loads increase dramatically, particularly in the inboard region of the blade. A key problem is to design a strong inboard region that supports these loads without sacrificing too much aerodynamic performance. A new design, the "biplane blade", is proposed: a biplane inboard region that transitions into a joint, which connects to a monoplane outboard region. The objective is to develop biplane inboard configurations that improve the aero-structural performance of blades. To approximately compare a conventional blade with a biplane blade, it was assumed that the structural performance of each of the blades' internal spars was representative of the entire blade. Several spars were designed to be simple approximations of a conventional blade ("monoplane spar") and the biplane blade ("biplane spar"). Canonincal bending loads were applied to each spar and their deflections and bending moments were compared. A parametric analysis of biplane spar configurations shows that their tip deflections and root bending moments are smaller than monoplane spars of the same length. These benefits for the inboard region could lead to weight reductions in wind turbine blades. Innovations that create lighter blades can make large (100-meter) blades a reality. These results suggest that the biplane blade may be an attractive design for large blades.

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