A Vertical Axis Wave Turbine With Cup Blades

Abstract

A new wave energy converter (WEC) design and some test results are discussed in this work. Among a variety of WEC technologies being explored to date, a huge majority employs wave-driven reciprocating motion (e.g., heave, pitch, sway, reciprocating bending or curving, etc.) to harness energy. It is well known that reciprocating WECs only work well at or near a predefined wave frequency, in a preferred alignment angle with the wave direction (except for the heave type), and in organized waves. But real ocean waves are chaotic and have daily changing frequencies and propagation directions. To circumvent those issues of the reciprocating WECs, a new unidirectional WEC concept — a vertical axis wave turbine — is explored in this research. The key component of the wave turbine is a rotor, which has a number of uniquely arranged hemispherical shells as blades. When the rotor is exposed in waves with its shaft vertically oriented, local water motion in any spatial directions (due to waves) can always drive the rotor for unidirectional rotation regardless of the wave type and propagation direction. In other words, the rotor can rely on omnidirectional water motion to realize its unidirectional rotation. A model wave turbine employing this rotor design has been tested in a wave flume. Upon a successful demonstration in simulated irregular waves, the rotor’s unidirectional performance was systematically characterized under various experimental conditions in simple waves.