Abstract
Cross-flow tidal turbines are an attractive option for powering remote or off-grid applications because of their simplicity as compared to axial-flow turbines. For instance, when oriented vertically, they harvest power from any current direction with a single degree of freedom and no yaw mechanism. Additive manufacturing (AM) offers an opportunity to print parts out of a wide variety of materials that can result in components that are lighter, stronger and/or less expensive to produce than with traditional manufacturing techniques. When coupled with cross-flow turbine rotors, which require critical features (blade-strut, strut-shaft connections) to be both structurally stiff and hydrodynamically shaped - a challenge for typical fabrication processes - AM offers the ability to do both well. Here we present ongoing work on the feasibility of using advanced AM techniques to fabricate small cross-flow turbine rotors for applications at sea and near remote coastal communities.
Plastic, metal, and ceramic advanced manufacturing materials were first reviewed for suitability based on a set of engineering requirements and criteria related to turbine characteristics, material properties, and AM process capabilities. From the selected materials, one set of samples were then tensile tested, while a second set was first conditioned in seawater tanks for 5 months and then tensile tested. Based on insights gained from these initial tests, one- and two-bladed rotors were printed from selected materials, set up, and characterized for loads and hydrodynamic performance in a laboratory flume.