MODEL TEST ON THE MOTION RESPONSE TO WINDS AND WAVES OF AN ARTICULATED TOWER CAPABLE TO MOUNT WIND TURBINE GENERATORS

While many articulated buoyant towers connected to a gravity base with a universal joint have been constructed for navigational aids on the sea bottom, such as in Tokyo bay, Japan's Coast Guardhas planned to develop advanced navigation aids system to mark ships navigation routes by laser lights. This kind of heavy duty tower would also require added its stability and motion characteristics forthe winds and waves. Therefore we conducted a 1/20 scale model test to measure wind loads acting to thedeck of the tower and inclinations of the tower by using a wind and wave tunnel. In this study, first we obtain drag coefficients for wind loadings on the deck as well as added mass coefficients of the tower by the natural free oscillation test. Then we compared test results with time domain analyses to determine the inertia and drag force coefficients of the tower. The paper also describes the transverse oscillation due to steady and fluctuating wind, wave loadings and combined wind and wave loadings.