Abstract
Here we investigate the performance of an experimentally tested model-scale oscillating water column (OWC) device, modified to only exploit half of the wave cycle. To do this we integrate a passive valve system into the OWC chamber which ensures a free connection to the atmosphere either on the up- or the down-stroke, but sends the flow through the orifice plate representing the full-scale air turbine, on the other half-cycle. The performance of the experimental model is evaluated from the absorbed power of the OWC chamber. The absorbed power is computed from the measured pressure drop across an orifice plate and the internal surface elevation inside the chamber. Perhaps surprisingly, the device can absorb more energy near resonance when exploiting only half of the cycle than when the full cycle is exploited. Since a one-way turbine is typically much more efficient than a Wells, impulse, bi-radial, or other self-rectifying turbine, this suggests a significant potential gain in overall efficiency from wave to wire. The obtained performance characteristics of the model-scale device are extrapolated to a proposed full-scale device size, and its performance is evaluated in Faroese waters. The performance of the proposed full-scale device is presented in terms of the annual absorbed power.