Experiment and simulation based selection of oscillating buoys for rack & pinion power take-off wave energy converters

Abstract

Wave Energy Converters (WECs) are explored on finding solutions to the energy sector as a renewable energy source for electricity and trying to convert the immense power available with ocean waves in the most efficient way. Many researches have been undertaken to improve varieties of WECs. However researchers have paid less attention towards the improvements of Rack & Pinion Power Take-off (PTO) WECs. Oscillating buoys are the most important part in most of the mechanical WECs which are used to absorb initial power from ocean waves. The aim of this thesis is to select the best performing oscillating buoys for Rack and Pinion PTO WECs by fulfilling the three objectives: (1) To identify Oscillating buoys suitable for Rack and Pinion PTO WECs, (2) To carry out simulation analysis to select the best performing oscillating buoys for Rack and Pinion PTO WECs, and (3) To conduct experimental analysis to select the best performing oscillating buoys for Rack and Pinion PTO WECs. The DMAIC (Define, Measure, Analyse, Improve & Control) cycle was used as the basis for the methodology. Six buoy types were selected based on the commonly available other types of WECs and this thesis focussed on simulation & experimental analysis to select the best performing oscillating buoys for Rack and Pinion PTO WECs. Simulations of all buoys were carried out with the help of Computational Fluid Dynamics (CFD) software X-Flow and three parameters, namely: Static Pressure, Vorticity & Liquid Phase, which were compared with each other. Proto type Rack and Pinion PTO WEC with regular wave making facility in a testing tank and six types of buoys in equal weight with the height to width ratio as 1 were fabricated and experimental testing were undertaken by creating four different wave heights for each buoy. Simulation and experimental results were analysed carefully and the best performing buoys for the proto type model of oscillating buoy operated, Rack & pinion PTO WEC were selected.