Experiments on a scale model of a monolithic concrete spar for floating wind turbines

Preliminary studies of a concept consisting of a monolithic concrete SPAR platform were presented in 2014. The studies were performed in the framework of the AFOSP KIC-InnoEnergy project (Alternative Floating Platform Designs for Offshore Wind Towers using Low Cost Materials) showing significant costs reduction. The experimental phase of the project was developed during 2014. The experiments comprised a set of hydrodynamic tests performed in the CIEM wave flume facility at the Universitat Politècnica de Catalunya (UPC), with a 1:100 scale model assuming Froude similitude. The complete experimental campaign included free decay tests, a set of 22 regular wave trains of different periods to determine the RAO’s and another set of 21 regular and irregular wave trains in conjunction with a mechanical wind device, simulating the mean thrust force exerted by the wind turbine. To adjust the weight of the whole system, a set of adjustable weights inside de scale model were designed assuring such properties, particularly the pitch/roll inertia. The scaled model of the mooring system was carefully studied because the constraints in width of the flume facility. A mechanical wind device was also specifically designed to ensure an averaged force at the top of the model, simulating the effect of the mean rotor thrust force. A detailed description of the methodology for the experimental campaign and a summary of the experimental results are presented.Peer Reviewe