Abstract
The responses of a monopile offshore wind turbine subjected to irregular wave loads are investigated numerically and experimentally, considering a range of sea states. An extensive experimental campaign was carried out on a fully flexible model, representative of a 5 MW offshore wind turbine, at 1:40 scale. An assessment of the experimental results for the response amplitude operator for regular waves and the 90th percentile seabed bending moment in long-crested irregular waves is carried out using two models (analytical and numerical) for uncertainty propagation, suggesting that bias errors in the model properties and in the wave elevation contribute the most to the total uncertainty. The experimental results are also compared to a numerical model using beam elements and Morison-type wave loads with second order wave kinematics. The numerical model does not capture all of the responses within the level of uncertainty of the experiments, and possible reasons for the discrepancies are discussed.
Highlights
The offshore wind industry is moving towards larger turbines in order to save costs on installation and maintenance
For monopile wind turbine foundations, this corresponds to an increase in diameter, and more significant wave loads
The main focus of the present paper is to identify the level of uncertainty in the experimental results, in order to understand whether or not the discrepancy between the numerical models and the experimental results is within the experimental uncertainty
Summary
The offshore wind industry is moving towards larger turbines in order to save costs on installation and maintenance. In severe weather conditions, when the turbine is typically parked with the blades feathered, monopile wind turbines are very lightly damped and sensitive to wave loads which excite resonant responses. In order to ensure safe yet economical design of large monopile wind turbines, the hydrodynamic loads and the ringing-type responses need to be predicted accurately. This paper presents an estimation of the uncertainty in the experiments, focusing on the long-crested wave conditions, as well as a comparison of the results with state-of-the-art engineering models. Repeatability is assessed directly from the experimental results, and possible bias errors are estimated and propagated to the responses of interest using a simple semi-analytical model and using a state-of-the-art engineering model. Results of the experimental campaign and numerical analyses are presented together, focusing on the ability of the numerical model to capture selected response metrics within the estimated experimental uncertainty. Differences between the numerical model and experimental results are examined
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
