The power-capture of a nearshore, modular, flap-type wave energy converter in regular waves
Bottom-hinged, nearshore flap-type wave energy converters (WECs), have several advantages, such as high power conversion efficiency and survivability. They typically comprise a single flap spanning their full width. However, a potentially beneficial design change would be to split the flap into multiple modules, to make a ‘Modular Flap’. This could provide improvements, such as increased power-capture, reduced foundation loads and lower manufacturing and installation costs. Assessed in this work is the hydrodynamic power-capture of this device, based on physical modelling. Comparisons are made to an equivalent ‘Rigid Flap’. Tests are conducted in regular, head-on and off-angle waves. The simplest control strategy, of damping each module equally, is employed. The results show that, for head-on waves, the power increases towards the centre of the device, with the central modules generating 68% of the total power. Phase differences are also present. Consequently, the total power produced by the Modular Flap is, on average, 23% more smooth than that generated by the Rigid Flap. The Modular Flap has 3% and 1% lower average power-capture than the Rigid Flap in head-on and off-angle waves, respectively. The advantages of the modular concept may therefore be exploited without significantly compromising the power-capture of the flap-type WEC.
Thank you to the technicians at QUB, for design guidance and model fabrication, and to the QUB Marine Research Group, for support during the experimental campaign and writing of this paper. This work was supported by the Energy Technologies Institute (ETI) and the RCUK Energy Programme for the Industrial Doctoral Centre for Offshore Renewable Energy (grant number EP/J500847/1). Thank you also to the sponsors of this research, Aquamarine Power Ltd and QUB for financial support and the latter for provision of experimental testing facilities.
This is the author accepted manuscript. The final version is freely available from Elsevier via the DOI in this record.
Available online 21 April 2017