Hydrodynamic characteristics of tidal turbines

The drive to develop marine renewable energy is pushing new technology and has highlighted a gap in the current knowledge. The flow round a cylinder has been extensively tested for the offshore industry and is reasonably well understood. Deploying marine renewable energy devices means installing cylindrical structure in areas with current-wave ratios that have not been tested in the offshore industry. The force acting on the cylindrical structure is very small when compared to the forces acting on a tidal turbine. There has been very limited work done on the inline wave-current forces acting on tidal turbines. This work uses Computational Fluid Dynamics to investigate the inline forces acting on a vertical axis turbine and a model experiment to calculate the inline forces acting on a horizontal turbine. Various CFD models were run and compared to published data as a means of validating the models. Experiments were carried out in the Newcastle Towing Tank on a towed oscillating tidal turbine. The in-line force on it was measured, and a Morison equation regression analysis was carried out on the experimental data. In the process of computer modelling the Savonius turbine was selected for the inline force simulations. This selection was based on the accuracy of CFD results for a give amount of processing time. The inline force acting on the Savonius was broken down into component parts representing a cylinder, the rotating turbine and the interaction of the cylinder and turbine. A relationship was found for these interactions and their relative importance in contributing to the in-line force was evaluated. The turbine displayed significantly different hydrodynamic characteristics from those of a simple equivalent cylinder.EThOS - Electronic Theses Online ServiceGBUnited Kingdo