<p>To maximize the energy production of a wave energy converter, applying reactive power is typically required, which needs to be supplied by a complex Power Take-Off (PTO) unit developed with high expenditure.&nbsp; On the other hand, the energy production will not be maximized by only applying a passive control.&nbsp; Therefore, this paper implements a novel Variable-Shape Buoy Wave Energy Converter (VSB WEC) that aims at eliminating the requirement of reactive power (only applies passive control) with minimum impact on the energy production (energy still is optimized).&nbsp; Unlike conventional Fixed Shape Buoy Wave Energy Converters (FSB WECs), the VSB WEC allows continuous shape-changing (soft) in response to ocean waves.&nbsp; The highly nonlinear interaction between the device and waves is expected to be utilized to produce more power with only passive control.&nbsp;&nbsp; In addition, the proposed device can operate in an optimal sense consistently under constantly changing sea climates.&nbsp;&nbsp; As far as survivability is concerned, the device can also be designed more economically compared to conventional FSB WECs (designed to be heavy and large to fight the wave loads under extreme wave conditions).</p><p>Numerical simulations are conducted to investigate the optimality, adaptivity, and survivability of the proposed device.&nbsp;&nbsp; The dynamic behavior of the VSB WEC is simulated in a Computational Fluid Dynamics (CFD) based Numerical Wave Tank (CNWT) by applying ANSYS 2-way fluid-structure interaction (FSI). &nbsp;The energy absorption of the VSB WEC is first numerically simulated by using a damping control, and its performance is compared with a conventional FSB WEC with the same dimensions.&nbsp; The results show the energy production is significantly improved by applying the shape-changing mechanism with only a passive control.&nbsp;&nbsp; Further, the performance of the device is simulated under a changing sea climate (varying peak period and significant wave height) and compared with an FSB WEC. The results show the VSB WEC enables a more consistent operation in an optimal sense than an FSB WEC, given the fact that the shape of the proposed device changes by responding to different wave conditions.&nbsp; Finally, the wave loads on the wet surface and the dynamic behavior of the device under extreme wave conditions are analyzed and compared with an FSB WEC numerically.&nbsp; The results show the wave loads on the device are significantly reduced compared to an FSB WEC, which indicates better survivability of the VSB WEC.</p>

Numerical Investigation on the Performance of a Variable-Shape Buoy Wave Energy Converter

Paper Proceedings: https://asmedigitalcollection.asme.org/OMAE/OMAE2021/volume/85116

OMAE 2021

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