Dynamic Loadings on Turbines in a Tidal Array (DyLoTTA)

Lead Institution: Cardiff University

Principal Investigator: Professor Tim O'Doherty 

The research will investigate the nature of the loading patterns imparted onto tidal stream turbines when positioned and operated within an array and develop operational procedures to mitigate the impacts of these extreme loading patterns. Exposure to open sea wave climates with high wave-current interactions will influence the power generating, structural integrity, product durability and maintenance requirements of the technologies deployed. The research will undertake both experimental and numerical analyses in a manner that will make the results and findings transferable to real-life implementations. This will inform developers of the peak and fluctuating loads that devices are exposed to in a commercial array environment and will also identify and test mitigating actions to be implemented in order to ensure the robustness and sustainability of the array. 

The dynamic, cyclic loadings on a tidal stream turbine have been shown to depend on the current profile and wave characteristics which can increase the severity of these loads. This must be considered in the design of the turbine. A turbine in an array will be subjected to more complex flows due to its position in the array, which will result in more diverse loading patterns, which must be fully understood by the turbine designers and operators. 

The project will therefore evaluate and measure the loading and performance of different configurations of tidal stream turbine arrays using numerical modelling and model scaled experiments. The numerical modelling will use fluid and structural modelling. An existing and proven, instrumented, laboratory scale turbine design will used for the tests. Initial work on a three turbine array will be undertaken to create models of a full-scale turbine array to determine the power output, loading patterns and accurate life-fatigue analysis based on realistic site deployment conditions. This information will be formulated to provide a basis for the industry to evaluate anticipated performance, monitoring needs, operational best practice and maintenance regimes in order to deliver the lowest cost of energy from tidal arrays.