Project Acronym: HYIII-DHI-10
1. / Title of Research Project / Dynamic response of floating offshore wind turbines under random waves and wind action2 / Facility - Location / DHI Shallow Water Basin
DHI
Agern Allé 5
DK-2970 Hørsholm
Denmark
3 / Summary / Capabilities for predicting wind and wave loads on floating offshore wind turbines have reached considerable interest in recent years; these structures represent both a great hope forrenewable energies due to the wind resource potential available in deep water areas and a significant challenge for engineers and scientists.
The knowledge of the behavior of floating offshore wind turbines (W/T) under wave and/or wind action remains one of the most difficult challenges in offshore engineering which is mostly due to the highly non-linear response of the structure.
The determination of design loads on offshore floating wind turbines is a complex topic involving different wave and wind models, load-calculation methods and probability analysis.
The primary aim of this research is intends to improve the understanding of the dynamic response of floating offshore W/T under combined wind and wave conditions like in deep waters.
In particular the objective of the tests was to obtain data on natural frequency and resonance conditions of two floating wind turbine designs, a tension leg platform and a spar buoy, identify the effects of the anchor chains in the response of the floating body, study hydrodynamic aspects of a floating wind turbine and to create a database for numerical model calibration and verification.
The dynamic behavior and the stress conditionsof two different types of floating wind turbines have been investigated: spar-buoy and tension leg platform.
The spar buoy presents a long mast having approximately half of itslength underwater; the tension leg platform presents a floating platform with steel lines tethered from its corners of thefloating platform to concrete-blocks or other mooring systems lying at the ocean floor (Figure 1).
Figure 1. Spar buoy and TLP floating wind turbines
Tests were performed simulating three basic meteo conditions:
1 - the dynamics of the floating structure were studied first under no rotation conditions (NR);
2 - operational conditions were simulated with combined rotation and wave impact (R);
3 - furthermore extreme conditions were simulated by extreme wave conditions (1/50 years) with the rotor being stopped.
Both floating turbines structures were tested using unidirectional regular and irregular waves. Furthermore normally incident waves as well as oblique waves under an angle of 20° were tested.
4 / Contact Information / Prof.Eng. Giuseppe Roberto Tomasicchio
University of Salento
73100 Lecce (Italy)
Tel.: +39 (0) 0832 29 7795
E-mail:
5 / Photos /
6 / Keywords / Keywords: floating wind turbines; tension leg platform; spar buoy; SPH
7 / Reference to publications / -Tomasicchio G.R., Armenio E., D’Alessandro F., Fonseca N., Mavrakos S.A., Penchev V., Schüttrumpf H., Voutsinas S.. “Dynamic response of floating off-shore wind turbines under wind and wave action”.Authors: Proceeding of ICCE2012 (International Conference on Coastal Engineering), Santander, Spain), July 2012
-D’Alessandro F., Armenio E., Tomasicchio G.R., Fonseca N., Mavrakos S.A., Penchev V., Schüttrumpf H., S. Voutsinas. Dynamic response of floating off-shore wind turbines under wind and wave action. SUBMITTED to ASCE Journal of Waterways, Port, Coastal, and Ocean Engineering (JWPCOE).
8 / Status / Finished in October 2012