Investigation of the influence of turbulence intensity and integral length scale on a tidal turbine

The interaction of turbulence with a tidal turbine is an area of interest that is little understood. Tidal flows are highly turbulent with a broad range of length scales and intensities between 5 to 20 %.
 The objective of the experimental work carried out during the last two weeks under the MARINET Project by a team of Southampton University is to investigate the effects of grid generated turbulence on a model tidal turbine. More specifically, to isolate the individual effects of turbulence intensity and integral length scale on the power output and thrust acting on a turbine. The effects of the turbulence characteristics on variance, or deviation, in power and thrust will also be considered in relation to fatigue.
 During this work, two grids have been used to generate turbulent flows with different characteristics. The turbulence intensity and integral length scale have been controlled by changing the grid bar width and the downstream location of the turbine. Both Shouthampton University turbine model (0.8 m diameter) and Ifremer turbine model (0.7 m diameter) have been used during these trials. The flow have been characterized by LDV measurements. The first results show a significant dependence on turbulence intensity of the turbine performances. 

 Grille permettant de générer un écoulement turbulent  / Grid used to produce a turbulent flowEcoulement turbulent généré en aval de la grille / Turbulent flow produced behind the grid
Hydrolienne de l'Université de Southampton dans un écoulement non turbulent / Turbine of Southampton University in a low turbulent flow