Modelling of an oscillating hydrofoil, with a fluid-structure interaction approach

As policies to fight greenhouse gas emissions are more and more demanding and as the global energy demand is constantly increasing, renewable energies are currently seen as an important contribution to the global energy mix. Among them, tidal energy has the advantage of a perfectly known and highly predictable intermittency. The present work is part of the PoHyCA (Hydrodynamic Pump for Air Compression) project led by Segula Technologies, consisting in the realization of an innovative hydrodynamic pump for air compression and storage. The final objective is the production of electrical energy. PoHyCA technology captures the energy of sea currents using an oscillating hydrofoil that moves under the effect of hydrodynamic forces from the surrounding flow. This work focus on the evaluation of the dynamics of the deformable hydrofoil. A fluid-structure interaction (FSI) approach, using an implicit coupling scheme, is implemented to account for the deformations of the structure, induced by hydrodynamic forces. The numerical model also takes into account the large pitching and heaving displacements of the structure. It is first applied to a rigid oscillating plate experimentally documented in the literature, and similar results are obtained. We show that the flexibility of the profile leads in particular to a reduction in propulsion capability. The model is then applied to a hydrofoil subjected to an oscillating heaving and pitching motion. We show that in certain configurations, blade deformations can improve energy efficiency. (author)