On Offshore wind turbine fatigue caused by wave influenced wind

Abstract

A wave influenced wind turbine simulator (WIWiTS) is developed and results from these simulations are used for fatigue analyses. WIWiTS is based on the Simulator fOr Wind Farm Application (SOWFA) developed at NREL. The simulations are transient with an unsteady Reynolds-Averaged Navier-Stokes (URANS) approach. An actuator line representation of the turbine is placed in a domain where the wave and wind are either aligned with each other or opposed to each other. Simulations with four different wave states are compared to a reference case with no waves, but the inlet wind is the same for all cases. The wave will influence the wind field, which in turn affects the damage equivalent load both at the blade root and at the tower base. In a relatively low wind regime (8 m/s in a height of 400 m) our simplified simulations show that the wave influenced wind increase the fatigue damage compared to a situation with no waves, especially for the cases where the wave opposes the wind field.