Research

My current research is the modelling of the forces that a buoy experiences in waves when it is attached to the Snapper generator. This is a time domain simulation which incorporates the electromagnetic forces as well as the forces from the waves and the buoys resulting motion.

This is a two year project which will result in a prototype device being built and tested in the wave tank at NaREC.

My PhD involved looking at the Power Take Off (PTO) of Wave Energy Converters (WECs). The PTO is the part of the WEC that transforms the relative motion obtained within or close to the WEC, into electricity. It was based on looking at a vertical axisymmetric surface piercing point absorber, limited to motion in heave. It is a generic device, that is self-contained and slack moored. I modelled the PTO as a nonlinear parallel system of springs and dampers.I am particually interested in how the PTO is coupled to the motion of the external shell of the WEC, and how this affects the motion of both components of the device. The nonlinear analysis is required due to the natural nonlinearity of the PTO.

I looked at three different types of nonlinearities that could occur in the PTO. 1) A hydraulic PTO setup, so that the force of the PTO is quadratically proportional to the velocity. 2) A mono-directional PTO, so the force of the PTO only operates in one direction, either expansion or compression. 3) The influence that having end-stops on the PTO has on the overall motion of the device and the power extraction.

I used both a numerical and physical model to study these effects. The numerical model is based in the time domain and acts as a summation of all the various forces that act upon the model. The experimental model is a 1:40 scale mode that is being tested in the Curved tank at Edinburgh university. The model is kept to moving in heave my a set of rod end bearings attached to platform within the tank.

If you feel you can help me with my research or wish to discuss my work further, please contact me on the details below.