Abstract
The aim of this work is to model the flow field around a horizontal axis tidal stream turbine to include the effects of both free surface proximity and wave induced velocities. Theoretical results are presented for the case of a linear array of tidal stream turbines that account for the proximity of the free surface and the seabed. The theory is then developed further to account for wave induced velocities and the resultant unsteady loading on a turbine. The theoretical results are compared to open channel flow experimental results. The flow field has been first experimentally simulated using various resistance discs. These results will be complemented by more detailed measurements using a model turbine. A combination of oscillatory flow and current is used to simulate the effects of wave and current motion on the turbine. The work on free surface proximity culminates in a blockage correction for free surface flows. The extension of this theory for inclusion of wave induced velocities provides a characterisation of the unsteady loading on the turbine due to the wave motion. Incorporation of the corrections for free surface proximity into a blade element code is discussed.