Hydrodynamic Modelling Of Tidal Turbine Arrays

Various types of tidal current turbines are tested and operated around the world,yet large scale production of tidal energy must rely on tidal turbine arrays.The wiling to build an array depends much on the performance of turbines within it.Considering the multi-scale and complex nature of the problem,theoretical modelling is the most efficient way to analyse the performance of tidal turbine arrays,especially the limitation of energy extraction.Encouraged by recent studies,we extend the classical momentum actuator disc theory to include the free surface effects and allow the vertical arrangement of turbines.The results show that the two dimensional array arranging turbines in both the vertical and lateral directions performs better than one dimensional array.Next,we combine the partial array model and channel dynamical model to investigate the effects of blockage,arrangement and channel-dynamics,respectively the key point of turbine,array and channel scale,on tidal turbines.The results suggest that when we increase the number of turbines in a row,the power per turbine may monotonously increase,decrease or get the maxima at certain global blockages.These different results mainly depend on characteristic parameters of the channel.Furthermore,optimal arranging would reduce the blockage to get maximum power.We also found that the optimal arrangement for each turbine density assuming constant velocity amplitude still has the largest power potential,yet the increase rate from reasonably arranging would be partly offset when we consider channel-dynamics.