Dynamics of cross-flow turbines with varying blade materials and unsupported blade span

Cross-flow turbines (CFTs) can be used to harness energy from tidal, river, or ocean currents. This work aims to reduce the levelized cost of energy of CFTs by using less rigid, less expensive materials and reducing the number of supports. To achieve this, turbine performance was investigated in a towing tank with a modular 1-meter diameter CFT with three blades and two struts. Blade material, strut separation distance, and tip speed ratio were varied while maintaining a sufficiently high towing speed for Reynolds number independence. For each material, the blades were instrumented with high-resolution fiber optic sensors to measure blade strain, providing insight on the impact of blade deformation on turbine performance. The reliability and survivability of CFTs in part depends on the fatigue life of the blade materials, which can be analyzed using a fluid-structure interaction (FSI) model that considers blade hydroelasticity. The collected high-quality, high-resolution experimental dataset is being used to validate computationally intensive FSI models, providing crucial groundwork to improve the efficiency and cost-competitiveness of CFTs.