Hydrodynamic analysis of turbine control through blade-deformation

This paper addresses the hydrodynamic potential for blade deformations to contribute to tidal turbine control strategies. We explore the practical limits for the operational characteristics of flexible tidal turbine blades in terms of power production and thrust force for two passive deformation strategies. We defined a parameter space of flapwise and twist deformations in which different deformed-blade geometries were constructed using parametrically and then simulated using a Reynolds-Averaged Navier-Stokes solver to determine the performance of the deformed blade as a function of tip-speed ratio. The simulation results were processed to build three-dimensional parameter spaces for power and thrust as functions of the flapwise deformation, twist deformation and tip speed ratio. The effect of two different passive blade deformation strategies, together with speed control, on turbine thrust and power over a range of operational flow speeds are shown, highlighting the trade-off that exists between below- and above-rated speed operation.