Optimal design of a tidal turbine

Abstract

An optimal design procedure has been applied to improve the design of an open-center tidal turbine. A specific software developed in C++ enables to generate the geometry adapted to the specific constraints imposed to this machine. Automatic scripts based on the AUTOGRID, IGG, FINE/TURBO and CFView software of the NUMECA CFD suite are used to evaluate all the candidate geometries. This package is coupled with the optimization software EASY, which is based on an evolutionary strategy completed by an artificial neural network. A new technique is proposed to guarantee the robustness of the mesh in the whole range of the design parameters. An important improvement of the initial geometry has been obtained. To limit the whole CPU time necessary for this optimization process, the geometry of the tidal turbine has been considered as axisymmetric, with a uniform upstream velocity. A more complete model (12 M nodes) has been built in order to analyze the effects related to the sea bed boundary layer, the proximity of the sea surface, the presence of an important triangular basement supporting the turbine and a possible incidence of the upstream velocity.