Cross comparison of two Analysis Tools for a Braceless Semi-Submersible Wind Turbine Versus Ocean Basin Test Results

In the frame of the IRPWIND project (Integrated Research Programme on Wind Energy), a benchmark is going on for comparing the numerical tools versus results obtained from ocean basin tests. A braceless semi-submersible wind turbine platform is considered herein. Real-time hybrid model (ReaTHM®) tests were done at 1:30 scale in MARINTEK’s Ocean Basin in 2015 (http://windbench.net/marintek). The goal was to estimate the performance of a novel hybrid technique which avoids the use of a physical turbine for reproducing the aerodynamic loads. Instead, these being representative of the Northern North Sea wind conditions, were in real time calculated by a Blade Element Momentum (BEM) software and subsequently applied by a 5-degree-of-freedom actuators on the structure. The mooring system was typical of a three catenary mooring lines while the waves were produced by flapping mechanisms at basin's borders. The above mentioned system produced experimental results that were taken as reference for calibrating numerical hydrodynamic and structural models [1, 2, 3].