Floating structure and wave energy converter

• Main Author: Goh, Wei Hong.
• Other Authors: Huang Zhenhua
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Civil engineering::Water resources
• Online Access: http://hdl.handle.net/10356/15774
• Institution: Nanyang Technological University

The attention that global warming has received in the past few years has led to increased urgency in developing of renewable energy. Of the forms of wave energy that are currently available, the OWC is the most matured and developed technology. To improve the cost-effectiveness of this technology, it was suggested that floating OWCs can be built. The early stages of the project involved designing of a floating OWC model that could be tested under laboratory conditions. We sought to find out if there were any differences between a floating breakwater and a floating OWC. Hence, the model was a floating breakwater that had adjustable front plates, so that they can be opened to form a floating OWC. Pilot tests were carried out to learn about the behaviour of the floating OWC in response to incoming waves and also to identify problems with our experimental design. Wave amplitude and pressure fluctuations were recorded and using graphical analysis, patterns were extracted to gather information regarding the optimum behaviour of the model. Using Fast Fourier Transform to find out the peak amplitudes for the various parameters measured, we used the pressure changes and wave amplitudes to attempt to predict the natural period of the model, and provide indicators of peak energy absorption efficiency of the model. Evaluation of the results showed that changes in pressure were reduced with longer wave periods, while there were increased wave reflections and transmissions. Also, it could be noted that the largest mode of movement was heave, which would help boost the efficiency of the OWC. However, sway and roll motions that were supposed to be minimised by the design of our model showed changes that were higher than our expectations. Inferring from our results, we found that the natural period of the model to be around 1.7s. In conclusion, we have designed a model that can float and is able to function as an OWC. However, more needs to be done in terms of the design of the model, before we are able to study the behaviour of the model effectively. By increasing the number of diagnostic equipment for measurement, more data can be collected that allow more thorough analysis to be done. Wave separation techniques could be implemented that would allow for calculation of transmission coefficients that will ultimately allow us to study the amount of energy absorbed, and subsequently find the conversion efficiency of the model.