A NUMERICAL ANALYSIS ON THE DYNAMIC BEHAV-IOR OF A SEASTAR TENSION LEG PLATFORM OFFSHORE WIND TURBINE AGAINST SEA LOADS

A numerical method is used to investigate a SeaStar tension leg platform (TLP) offshore wind turbine response behavior in parked condition. Since the tethers do not let TLP move largely in heave, roll and pitch, the movements of surge and sway are the most important ones in TLP. This code considers nonlinearities due to changes in tension of tethers. Wave forces are calculated adopting the Airy wave theory. Since cylinder is slender in comparison with exerted waves, diffraction effects can be neglected. Furthermore, shear turbulent wind is exerted on tower, with maximum speed 30 m/s on the hub. Since surge and pitch movements of the TLP platforms are coupled, the off-diagonal components of stiffness, damping and mass matrices are considered to calculate coupling. This code solves nonlinear equation of motion in each time step to calculate pitch, surge, heave and their velocities and accelera-tions. The Results of each time step will be used as input for the next step. In this way, the equation of motion will be solved in time domain. In addition, three concepts are tested here to find out best response of the concepts. In consideration of its results, response behavior of the prototype in different environmental conditions will be demonstrated.

Keywords:

Seastar TLP Offshore Wind Turbine , Numerical Solution , Dynamic Response Behavior , Wind and Waves