A Study on Structural Responses of Offshore Wind Turbines by Slamming Loads

Abstract

Offshore structures operating at sea are severely affected by slamming pressure. This slamming pressure significantly shortens the design life of offshore structures including offshore wind turbines and results in personal and material damage. This slamming load has to be fully considered in the design phase of the structure, and therefore good quality of experimental results should be supported. In Korea, offshore wind turbines have excellent conditions geographically. In the West sea, the construction of the jacket-type wind turbine is advantageous because the water depth is low, and in the East sea, which is relatively deep, the floating wind turbine is possible; thus, it is easy to generate a large-scale wind farm. For offshore wind turbines, several technical aspects should be considered. Among them, the damage of the structure caused by the slamming load should be studied. In the case of FOWTs operating in large waves, slamming can cause structural damage, and repeated slamming loads reduce the structural strength and shorten the design life. The slamming load should be calculated by applying the maximum peak, its width, duration and the dynamic load according to the natural period of the structure, and the importance of structural design. The results of the experiments can be used to determine the structural design, and the slamming load can be estimated to provide the design techniques offshore wind turbines as the design variables. In this study, we investigated experimentally the elastic effects of a cylindrical model on the slamming load characteristics by free drop test at height 1.0m and 1.7m.