Integrated analysis of scour effects for an offshore wind turbine truss tower design

Abstract

The scope of this thesis has been to investigate the effects of scour on an offshore wind turbine. This was done using HAWC2, a computer code which allows the fully-integrated analysis of the wind turbine, as opposed to the commonly used sequential approach.

The mean and standard deviation of the loads in two different nodes were studied. For one joint both the mean and the standard deviation increased when scour increased. For the other joint the mean was constant, while the standard deviation increased as a function of scour. It was found that for scour larger than 6 m, a sudden increase in the means and the standard deviations occurred. This couldbe caused by an error in the model, but it would be interesting to investigate this further.

The accumulated fatigue damage was estimated using the rainow counting algorithm by Adam Nieslony and the Palmgren-Miner rule. The data seemed to suggest that the damage increased with increasing scour, but it is diffcult to say whether this will be noticeable in practice.