Design of composite tidal turbine blades

Abstract

Tidal turbine blades are subjected to significant thrust and torsional loadings due to the high density ofthe seawater in which they operate. These thrust loadings lead to high bending moments at the bladeroot, which can prove to be a serious design constraint for these devices and can have implications withrespect to cost-effectiveness and scalability. This work presents a combined hydrodynamic-structuraldesign methodology for a commercial scale (1.5 MW) tidal turbine. A hydrodynamic analysis of theblade is carried out to determine force distributions along the blade span under normal and extremeoperating conditions. Using output from the hydrodynamic model, a pre-processor for computing bladestructural properties is used to determine the strain distribution along the blade spar caps. The straindistributions from this analysis are then compared with a finite element model of the blade which is thenused to compare the structural performance of glass fibre reinforced polymer (GFRP) and carbon fibrereinforced polymer (CFRP) as spar cap materials.