Abstract
Tidal turbines are submitted to numerous restarts and probably to changes of direction of rotation. The study of the start-up phase is then crucial: for which f low speed will the turbine start to rotate and generate electricity? How long does it take to reach the targeted rotational speed? Our study shows an innovative way to study fluid-structure interactions for tidal turbines. In most of tidal turbine performance investigations, the rotation is controlled by an engine for experimental approaches, or directly by the code with numerical approaches. With a forced rotation, it is then difficult to study the startup speed and phase. A flow-induced rotation is more respectful of the energy recovery chain, from the flow to the blade kinetics and energy recovery system. Here, we present a flow-induced model built within the open source software OpenFoam and applies to a 3D horizontal tidal turbine. Because of the lack of experimental data, the flow-induced model is validated using a comparison with an equivalent forced rotation model on which a mesh convergence study has been previously performed. Results show a good response of OpenFoam that generates the same wake in both cases of rotation (when the rotation speed is the same). This system could be used to study new tidal turbine concepts. In the future, this solution could be adapted and applied to tidal turbines strongly changing the global potential prediction studies