Combined bem-cfd modelling of tidal stream turbines using site data

Abstract

Marine currents have the potential to provide a large proportion of Britain’s energy generation requirements. Whilst a number of devices capable of utilizing this resource are under development, there is at present little exploitation of marine energy. One potential generator of energy in this area is tidal stream turbines (TST). However, since they are expensive to install, engineers need to ensure that the TST will deliver optimum performance once they are in place. This performance is dependent on a number of features that are specific to the surrounding environment, including the underlying bathymetry and variation of the current both temporally and within the water column. Computational fluid dynamics (CFD) is a useful tool for predicting what impact the surrounding environment and supporting structure will have on the performance of a TST. In this paper the importance of using measured site data to develop CFD models for TSTs is demonstrated. A CFD model of a TST is presented and two designs for the supporting structure are investigated. A parametric study is carried out using a flat bed model. Finally, a series of results is presented for a site in the Severn Estuary using a bathymetry defined bed.