A Vertical Axis Wave Turbine With Hydrofoil Blades

This work discusses a new wave energy converter (WEC) design that, when deployed in waves, performs unidirectional rotation about a vertical shaft. The uniqueness of this new WEC design is on utilizing omnidirectional water flow generated by waves to drive a rotor to perform unidirectional rotation about a vertical axis. This unique feature circumvents the frequency-dependent issue of common WECs, and eliminate realignment needs to cope with dynamically changing wave propagation directions. The key component of the WEC is a rotor, which has a vertical shaft with a number of blades mounted to it. Each blade has a hydrofoil-shaped cross section and is in a bent shape along its span. The spanwise bending of the blades makes the rotor capable of gaining a unidirectional driving torque about the vertical shaft no matter in which spatial direction the local water is passing by. For validating the WEC design and gaining preliminary understanding, a very first rotor model without any parametric optimization was built. Two types of experiments were then carried out by employing this model. In the first type, the model was translated (with the shaft vertically aligned all the time) in still water along a horizontal direction (back and forth), a vertical direction (up and down), and a circular orbit in a vertical plane. In the second type, the model was exposed in waves generated in a wave flume. In all the experiments, well-established unidirectional rotation of the rotor about its vertical shaft has been observed. The hydrodynamic performance of the rotor in waves was further characterized through systematic experiments under various conditions.