Session: 09-01-05 Wind Energy: Aero-hydrodynamics 5

Paper Number: 127967

127967 - Estimation and Experimental Validation of Extreme Waves and Loads on a Large Mono-Pile 

Numerical wave analyses of extreme sea states have been performed for a large monopile subjected to 50 year and 500 year hurricane conditions. The numerical analyses have been established using the REEF3D::FNPF software. The wave kinematics has then been combined with a Morison type load model containing a modified inertia term, KC dependent drag and a Weynberg-Campbell slamming term. The line loads generated from the numerical hydrodynamic analyses are then implemented into the SIMA FE solver to establish the extreme WTG responses.
 
The extreme statistics of hydrodynamic and structural response has been investigated and compared with results from model tests. The model test data sample is considerable and consist of 20x3h series of seed variations, including variations between sea states and mudline boundary conditions. When evaluating parameters such as crest height, steepness, we observe that the numerical wave tank approach allows for similar extreme behaviour as the observed in model tests.
 
In general, the numerical and experimental results agree well when comparing the extreme statistics. Beyond this, we also compare the extreme events in the slamming zone. This implies that we sequence the max load events for both experiments and numerical analyses and sort them by magnitude before making a direct time domain comparison of each of the sorted extreme events. The correspondence between model tests and numerics for the splash zone loads, is also observed for the overall response statistics.
 
Finally, we also make a comparison of spatial wave response, splash zone loads and structural response between the REE3D::FNPF based models and more traditional ways of describing extreme waves in design, such as the constrained wave methods described in IEC61400-3-1 .

Presenting Author: Csaba Pakozdi SINTEF Ocean

Presenting Author Biography: 2000 TU Berlin Dipl.Ing. Naval Architect
2000-2002 TU Berlin Researcher
2003-2008 NTNU, Trondheim PhD
2007- SINTEF Ocean (former MARINTEK)

Authors:

Csaba Pakozdi SINTEF Ocean
Hagbart Alsos SINTEF Ocean
Senthuran Ravinthrakumar SINTEF Ocean
Synne Nybø SINTEF Ocean
Louise Rolland EQUINOR
Knut Nordheim EQUINOR