Author(s)

A. Nematbakhsh, D. J. Olinger & G. Tryggvason

Abstract

The dynamic motion of floating wind turbines is studied using numerical simulations. The full Navier-Stokes equations are solved on a regular structured grid, using a level set method for the free surface and an immersed boundary method to model the turbine platform. The response of a tension leg platform to moderate amplitude waves is examined and the effect of a key design parameter is quantified in this initial study. It is shown that the pitch and surge motion amplitudes are larger than heave motions, and that increased ballast weight helps to stabilize the platform motions and reduce tether tensions. Keywords: floating wind turbines, numerical simulation, fluid-structure interaction, level-set methods. 1 Introduction Using wind to produce electricity is attractive since wind resources are relatively plentiful, the basic technology is well developed and it is rapidly becoming economically competitive with conventional carbon based electricity production. As its use has grown, however, concerns have emerged. Places best suitable for land-based wind-turbines, such as the plains of the midwest United States, are often located far from densely populated areas along the coasts; and a nonnegligible fraction of the population objects to the visual impact of wind-turbines on beaches, mountaintops, and most places in between. Placing floating wind turbines far offshore avoids most of these concerns. The wind is usually stronger and steadier, and the potential negative impact of the turbines is minimal.

Keywords

floating wind turbines, numerical simulation, fluid-structureinteraction, level-set methods