Press and announcements

Test tank to tidal channel: improved turbine load predictions

To mitigate the risk and uncertainty associated with turbulent flows in tidal channels, developers often use tank experiments and numerical simulations to assess the power and loading performance of a turbine. Previously there has been no method to scale these controlled flows to represent the natural turbulence present in tidal channels. 
 
The goal of the InSTREAM project was to determine the scaling between the turbulent flow conditions in a tank and in a tidal channel, so that numerical simulations of such
flows can be used to estimate uncertainties of turbine performance.
 
The project included the development of a sensor system that combined acoustic (Doppler), and non-acoustic (electro-magnetic and shear probe) technology that could be used in both laboratory and field applications. The system was successfully deployed at the University of Edinburgh's FloWave Ocean Energy Research Facility and in the Minas Passage, Bay of Fundy. 

The InSTREAM project found significant differences between the turbulence characteristics in the tank and in the field. The 3D eddies observed in the field were, in relative terms, about three times larger than those generated in the tank, resulting in considerable differences in power and fatigue loading.

A scaling method has been developed to allow direct comparison and translation between the two flow regimes.  This greatly increases the usefulness of tank testing and numerical modeling, and can be reproduced for other test tanks. It also allows site-specific field measurements to be translated to tank experiments, enabling numerical models (validated by tank experiments) to be used for reliable and realistic estimation of turbine and array performance. 

InSTREAM project partners were: Rockland Scientific Instruments; Dalhousie University; Blackrock Tidal Power; University of Edinburgh's Flowave Ocean Research Facility; European Marine Energy Centre and Octue, with financial support from Canada's Offshore Energy Research Association and Innovate UK.