Many wave energy convertors are designed to utilise either vertical (heave) or horizontal (surge) movements of waves. But the frequency response of small heaving buoys and oscillating water column devices shows that they are too stiff and so their resonance is at too short a period. A device moving in the horizontal (surge) direction has less restoring spring and so its resonance is at too long a period. It follows that a device that moved at some intermediate slope angle could have an intermediate value of hydrodynamic stiffness and so be resonant at a variable and desirable part of the wave spectrum. There have been two series of model tests in this work. The first used a simple free-floating model with no power take-off apparatus and with constraint achieved by means of a large inertia plate lying in the slope plane. The second used a rig that constrained the slope movement of the buoy head by means of hydrostatic bearings running on a guide rod set to the chosen slope angle. An external power take-off system was used to simulate a linear damper for absorbing the incident wave energy and control the motion of the model. The thesis firstly studies of the potentiality of varying the slope angle as a way of tuning the natural period of the device to suit wave conditions. Secondly, it studies of the experimental and theoretic at power capture ability of models with different slope angles in regular waves in the frequency domain. The hydrodynamic coefficients of the model were determined both experimentally and numerically based on linear hydrodynamic concepts. The power absorptions of the models were calculated using the experimental data of the hydrodynamic coefficients and also measured directly. Some control of power take-off were also investigated. Some irregular wave tests were carried out for the 45 degrees slope angle case.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:642804 |
| Date | January 2000 |
| Creators | Chia-Po, L. |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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