Experimental and numerical study of the response of the offshore combined wind/wave energy concept SFC in extreme environmental conditions

This paper deals with an experimental study of the survivability of the offshore combined concept Semisubmersible wind energy and Flap-type wave energy Converter (SFC) and with comparisons of the experimental data with numerical predictions. The SFC is a combined energy concept consisting of a braceless semisubmersible type floating wind turbine and three fully submerged rotating flap-type Wave Energy Converters (WECs). In order to study the survivability of the concept the focus is on extreme environmental conditions. In these conditions the SFC will not produce wind or wave power; the wind turbine is parked with the blades feathered into the wind and the WECs are released to freely rotate about their axis of rotation. Firstly the development and set-up of the physical model are presented. Static, quasi-static, decay, regular waves and irregular waves with wind loading tests are conducted on an 1:50 scale physical model. Aligned and oblique wave with wind loading conditions are considered. Measured variables that are presented include motions of the semisubmersible platform in six rigid body degrees of freedom, rotation of the flap-type WECs, tension of mooring lines, internal loads of the arms that connect the flap with the pontoon of the platform and tower base bending moment. The experimental data are compared with numerical predictions obtained by a fully coupled numerical model. The comparison is made at model scale. A good agreement between experimental data and numerical predictions is observed confirming the accuracy of the numerical models and tools that are used. The discrepancy between numerical and experimental results is smaller for regular than irregular waves. Compared to oblique conditions a better agreement between experimental and numerical results is obtained for the case of aligned wave and wind loadings. The results obtained demonstrate the good performance of the SFC concept in extreme environmental conditions. No strong nonlinear hydrodynamic phenomena are observed in the tests.

[1]  Madjid Karimirad,et al.  V-shaped semisubmersible offshore wind turbine: An alternative concept for offshore wind technology , 2015 .

[2]  Erik-Jan de Ridder,et al.  Comparison of Model Tests and Coupled Simulations for a Semi-Submersible Floating Wind Turbine , 2014 .

[3]  Vincenzo Nava,et al.  On the assessment of extreme forces on a floating spar wind turbine , 2013 .

[4]  Torgeir Moan,et al.  Hydroelastic code-to-code comparison for a tension leg spar-type floating wind turbine , 2011 .

[5]  Dominique Roddier,et al.  Design of a Point Absorber Inside the WindFloat Structure , 2011 .

[6]  Gregorio Iglesias,et al.  The new wave energy converter WaveCat: Concept and laboratory tests , 2012 .

[7]  John Ringwood,et al.  Comparison of the Experimental and Numerical Results of Modelling a 32-Oscillating Water Column (OWC), V-Shaped Floating Wave Energy Converter , 2013 .

[8]  Frank Adam,et al.  Evaluation of internal force superposition on a TLP for wind turbines , 2014 .

[9]  Odd M. Faltinsen,et al.  Sea loads on ships and offshore structures , 1990 .

[10]  Dominique Roddier,et al.  Modeling of an Oscillating Water Column on the Floating Foundation WindFloat , 2011 .

[11]  Jason Jonkman,et al.  Dynamics of offshore floating wind turbines—analysis of three concepts , 2011 .

[12]  Tor Anders Nygaard,et al.  Comparison of Experimental Results and Computations for Tension-Leg-Buoy Offshore Wind Turbines , 2015 .

[13]  Torgeir Moan,et al.  Characteristics of a Pitching Wave Absorber with Rotatable flap , 2012 .

[14]  Jason Jonkman,et al.  Summary of Conclusions and Recommendations Drawn From the DeepCwind Scaled Floating Offshore Wind System Test Campaign , 2013 .

[15]  Torgeir Moan,et al.  Joint Distribution of Environmental Condition at Five European Offshore Sites for Design of Combined Wind and Wave Energy Devices , 2015 .

[16]  Torgeir Moan,et al.  Dynamic response and power performance of a combined Spar-type floating wind turbine and coaxial floating wave energy converter , 2013 .

[17]  A. Courbois,et al.  Étude expérimentale du comportement dynamique d'une éolienne offshore flottante soumise à l'action conjuguée de la houle et du vent , 2013 .

[18]  Dominique Roddier,et al.  WindFloat: A floating foundation for offshore wind turbines , 2010 .

[19]  Torgeir Moan,et al.  Comparative numerical and experimental study of two combined wind and wave energy concepts , 2016 .

[20]  Torgeir Moan,et al.  Stochastic dynamic load effect and fatigue damage analysis of drivetrains in land-based and TLP, spar and semi-submersible floating wind turbines☆ , 2015 .

[21]  Torgeir Moan,et al.  Design considerations for tension leg platform wind turbines , 2012 .

[22]  Torgeir Moan,et al.  Design and Analysis of a Braceless Steel 5-MW Semi-Submersible Wind Turbine , 2016 .

[23]  Maurizio Collu,et al.  Preliminary design of a floating support structure for a 5 MW offshore wind turbine , 2012 .

[24]  Torgeir Moan,et al.  Numerical and Experimental Investigation of a Novel Wave Energy Converter , 2012 .

[25]  Aurélien Babarit,et al.  C-HyP: A Combined Wind and Wave Energy Platform With Balanced Contributions , 2013 .

[26]  António F.O. Falcão,et al.  Wave energy utilization: A review of the technologies , 2010 .

[27]  Johannes Falnes,et al.  A REVIEW OF WAVE-ENERGY EXTRACTION , 2007 .

[28]  Jason Jonkman,et al.  Validation of a FAST semi-submersible floating wind turbine numerical model with DeepCwind test data , 2013 .

[29]  Torgeir Moan,et al.  Effect of Flap Type Wave Energy Converters on the Response of a Semi-Submersible Wind Turbine in Operational Conditions , 2014 .

[30]  Francois Flocard,et al.  Laboratory experiments on the power capture of pitching vertical cylinders in waves , 2010 .

[31]  J. N. Newman.  Second-order, slowly-varying Forces on Vessels in Irregular Waves , 1974 .

[32]  Jason Jonkman,et al.  Definition of the Semisubmersible Floating System for Phase II of OC4 , 2014 .