| Popis: |
As modern wind turbines continuously grow in scale and capacity, rotor blade mass and cost have become major design drivers. For offshore windfarms where construction, maintenance, and service are particularly challenging, blade mass and cost concerns are even more critical. A biplane rotor design concept, proposed by Wirz et al. at the University of California Los Angeles, is explored in this study as a means of reducing blade mass and cost. The biplane design replaces the thick airfoil shapes commonly found in the root region of conventional rotors with two thinner airfoils arranged in a biplane configuration. In the present study, this biplane design concept is applied to a redesign of the NREL 5 MW rotor, representative of modern large-scale offshore wind turbines. It is observed that the performance of the proposed biplane configuration is comparable to the baseline NREL 5 MW design at rated wind speeds, with potential mass-savings. However, the structural analyses also indicate significant stress concentration at the junctions where the biplane configuration is connected to the monoplane regions. A more detailed structural design would be necessary to alleviate stress concentrations in these areas and improve the overall structural characteristics of the rotor. |
