Abstract
Hydrokinetic turbines are increasingly seen as a promising way to generate renewable energy from tidal and river currents, offering high energy density without the ecological costs of dams or large-scale hydropower. Placing turbines close to the free surface allows them to access higher flow velocities and thus greater power potential, but it also makes them more vulnerable to wave-current interactions. Horizontal-Axis Hydrokinetic Turbines (HAHTs) have shown strong potential at full scale, but their development and testing at laboratory scale are still constrained by scaling effects, limited structural data, and an incomplete understanding of unsteady wave-induced loads. Moreover, only a handful of studies document the detailed design process of model-scale turbines, and even fewer investigate the structural performance of 3D-printed blades. To help close these gaps, this thesis presents the design, construction, and experimental testing of a 0.74 m diameter model-scale HAHT developed at the TU Delft.
The design process combined actuator disc theory and Blade Element Momentum Theory (BEMT) to define the blade geometry and expected operational loads. A modular hub concept with adjustable pitch and interchangeable blades was developed, allowing rapid prototyping and cost-efficient manufacturing. The blades were produced using 3D printing, and static tests confirmed that they withstood thrust forces up to 441 N without failure. The nacelle was conceptually designed but not constructed; instead, the existing gondola system was employed for testing.
Experiments in the towing tank under steady and wave conditions showed good agreement with BEMT predictions once Reynolds numbers exceeded 1.1 * 105. The turbine achieved a maximum power coefficient of approximately 0.44, comparable to other model-scale studies. Under wave forcing, mean power remained stable, but unsteady loads dominated, with torque oscillations over 100% of the mean. Tip deflections of up to 33 mm were observed during operation, far exceeding static predictions, which underscores the role of deformation in dynamic response.
Overall, the study shows that it is possible to build a reliable and affordable model turbine using 3D printing and modular design, and to validate it experimentally. The results not only demonstrate the feasibility of this approach, but also underline how strongly turbine performance is shaped by Reynolds number effects, wave-current interaction, and fluid-structure dynamics. This makes the turbine a practical platform for future research and development in hydrokinetic energy.
