Which Features Must be Included in a Numerical Model for Large-Scale Tidal Farm Design?

Lead Research Organisation: University of Cambridge
Department Name: Engineering

Abstract

A key concern for tidal farm developers and investors is resource quantification. The ultimate aim of this project is to develop a tidal farm design tool that produces trustworthy results while requiring a level of computing power that is appropriate to industrial design. Once developed, the model can be extended towards analysis of sediment transport and thus can be used to understand the effect of large farms on the marine environment, which will be a key area of concern to stakeholders in the future.

Planned Impact

By analysing a site that has already been simulated using more traditional methods (Pentland Firth), the key issues associated with using depth-averaged shallow water models will be elucidated. This will be of use to tidal site developers who need to be able to interpret such low-order data, and also for academics working in the field. Using publically-available data, it will be possible to compare the large-scale RANS simulation to low-order simulations and determine which physical phenomena must be modelled.

The high-fidelity data generated will also provide a useful benchmark for other UK researchers to use in testing their models.

The ultimate aim will be to develop a design tool that produces trustworthy results while requiring an appropriate level of computing power for industrial design. To aid this, Cambridge will run a workshop with Alstom Ocean Energy in which the model will be showcased and further development will be undertaken.

Once developed, the model can be extended towards analysis of sediment transport and thus can be used to understand the effect of large farms on the marine environment, which will be a key area of concern to stakeholders in the future.
 
Description The research has uncovered significant findings related to the design of tidal turbine farms:
1. There is a significant change in the modelled flow behaviour and power output of a tidal turbine farm when the computational model is changed from representing the turbines in the simplest possible way (as actuator disks) to a more realistic model (Blade Element Momentum Theory disks).
2. When turbines are spaced close to each other, there is interaction between the wakes of adjacent devices. This should therefore be considered when modelling farm behaviour. This effect is more pronounced with the more realistic Blade Element Momentum simulations than with the actuator disk modelling.
3. An existing analytical model developed at Oxford can be adjusted to take into account interactions and feedback between turbines and the channel at all scales simultaneously (local device, array and channel scale).This creates modest changes to the farm power output predicitons.
Exploitation Route The use of Blade Element disks in farm modelling instead of simple actuator disks could be undertaken by anyone doing research into turbine placement and power output. There is a forthcoming technical note describing this method.
The adjustments to the analytical model could also be included in other people's models now that they have been published in the Journal of Fluid Mechanics
Sectors Energy,Environment
 
Description Collaboration with Edinburgh 
Organisation University of Edinburgh
Country United Kingdom 
Sector Academic/University 
PI Contribution Research Synergies between Dr Anna Young and Dr Ignazio Maria Viola identified as a result of the workshop in Dalian (Jan 2015). This led to an application for further funding to SUPERGEN Marine Challenge (waiting to hear result)
Collaborator Contribution Meetings to discuss scientific outcomes of Newton Fund project and future collaborative projects.
Impact Application for SUPERGEN Marine Challenge 3 funding
Start Year 2015