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

Potential Impact:
The impact of this research will directly effect decisions made by marine renewable technology developers; regulatory compliance bodies; Government and Legislative agencies developing policy; International standards bodies; investors, insurers and array developers. This provides the additional confidence necessary for the next stages of evolution for the marine renewables industry.

Better understanding of the loadings and fatigue induced in dynamic sea conditions will enable marine renewable technology developers to better design their product for operational conditions and more accurately schedule servicing requirements and intervals without relying on expensive over-engineering as per current practice, this delivering a more cost effective product.

Regulatory compliance bodies (DNV/ GL, LR etc.) will benefit from this new knowledge and understanding to enable more informed and apposite development of design codes used for undertaking compulsory third party verification. Ensuring codes are appropriate and fit for purpose and not merely an adaption of offshore engineering codes from the oil and gas sector.

Government and Legislative agencies, The Crown Estate, Regional and Local Authorities, etc responsible for developing policies for marine renewable deployment will be informed as to the nature of sites which can cost effectively harness marine renewable resource, and use this to deliver more realistic policies on enabling and quantifying resource extraction capabilities and which locations/ sites can be more cost effectively utilised in the early stages of commercial development of the marine renewable sector.

International Standards bodies, in the form of IEC Technical Committee 114 and IEA OES, will be informed with more accurate information on resource dynamics and resulting intensity, how this interacts with marine renewable technology and impacts on performance in order to inform standards being developed for device performance quantification, energy predictions from arrays and the cost of energy from marine renewable arrays.

Delivery of more accurate load quantification techniques will provide Insurers and investors with higher levels of confidence in assessing risk associated with array development and operations. Such premiums can be a considerable overhead on project costs, more accurate information associated with loads, fatigue and failure will allow premiums to be more reflective of risk while and minimise inbuilt contingency costs. This will reduce array project costs being experienced by investors and array developers and will deliver a lower levelised cost of energy from the project.