This study compares the time-varying rotor thrust and shaft power characteristics of a yawed floating offshore wind turbine (FOWT) predicted by three different open-source aerodynamic models. These models involve the blade-element-momentum (BEM) and the general dynamic wake (GDW) methods implemented in the design code fast developed by NREL, and a higher fidelity free-wake vortex model (FWVM) that is capable of modeling the unsteady skewed helical wake development of the yawed rotor. The study is based on the NREL 5 MW baseline rotor installed on the MIT tension-leg platform (TLP) operating with different rotor yaw angles and under regular sea wave conditions. Both the undisturbed wind speed and rotor speed are maintained constant throughout the analysis, though different sea wave heights and periods are considered. Initially, the motions of the FOWT under both axial and yawed rotor conditions are estimated in a time domain using fast. These motions are then prescribed to winds, an open-source FWVM developed by the University of Massachusetts Amherst, to determine the aerodynamic rotor thrust and power as a function of time. Both TLP surge and pitch motions are noted to impact the rotor thrust and power characteristics considerably. The three models have consistently shown that the TLP motion exhibits a negligible impact on the time-averaged rotor shaft thrust and power of the yawed rotor. On the other hand, the cyclic component of rotor thrust and power are found to be significantly influenced by the wave state at all yaw angles. Significant discrepancies between the predictions for this cyclic component from the three models are observed, suggesting the need of further research through experimental validation to ensure more reliable aerodynamics models are developed for floating wind turbine design software packages.

References

References
1.
Leishman
,
J. G.
,
2002
, “
Challenges in Modeling the Unsteady Aerodynamics of Wind Turbines
,”
Wind Energy
,
5
(
11
), pp.
85
132
.
2.
Hand
,
M.
,
Simms
,
D.
,
Fingersh
,
L.
,
Jager
,
D.
,
Cotrell
,
J.
,
Schreck
,
S.
, and
Larwood
,
S.
,
2001
, “
Unsteady Aerodynamics Experiment Phase VI: Wind Tunnel Test Configurations and Available Data Campaigns
,” National Renewable Energy Laboratory, Golden, CO, Technical Report No. NREL/TP-500-29955.
3.
Maeda
,
T.
,
Kamada
,
Y.
,
Suzuki
,
J.
, and
Fujioka
,
H.
,
2008
, “
Rotor Blade Sectional Performance Under Yawed Inflow Conditions
,”
ASME J. Sol. Energy Eng.
,
130
(
3
), p.
031018
.
4.
Schepers
,
J. G.
,
Boorsma
,
K.
,
Cho
,
T.
,
Gomez-Iradi
,
S.
,
Schaffarczyk
,
P.
,
Jeromin
,
A.
,
Shen
,
W. Z.
,
Lutz
,
T.
,
Meister
,
K.
,
Stoevesandt
,
B.
,
Schreck
,
S.
,
Micallef
,
D.
,
Pereira
,
R.
,
Sant
,
T.
, and
Madsen
,
H. A.
,
2012
, “
Final Report of IEA Task 29, Mexnext (Phase 1), Analysis of Mexico Wind Tunnel Measurements
,” Energy Research Center of the Netherlands, Petten, The Netherlands, Report No. ECN-E-12-004.
5.
Micallef
,
D.
,
2012
, “
3D Flows Near a HAWT Rotor: A Dissection of Blade and Wake Contributions
,” Ph.D. thesis, Delft University of Technology, Delft, The Netherlands.
6.
Krogstad
,
P. Å.
, and
Adaramola
,
M. S.
,
2012
, “
Performance and Near Wake Measurements of a Model Horizontal Axis Wind Turbine
,”
Wind Energy
,
15
(
5
), pp.
743
756
.
7.
Schepers
,
J. G.
,
2012
, “
Engineering Models in Wind Energy Aerodynamics—Development, Implementation and Analysis Using Dedicated Aerodynamic Measurements
,” Ph.D. thesis, Delft University of Technology, Delft, The Netherlands.
8.
Glauert
,
H.
,
1926
, A General Theory of the Autogyro,
ARC/R&M-1111
, pp. 558–593.
9.
Pitts
,
D.
, and
Peters
,
D.
,
1981
, “
Theoretical Prediction of Dynamic Inflow Derivatives
,”
Vertica
,
5
, pp.
21
34
.
10.
Suzuki
,
A.
,
2000
, “
Application of Dynamic Inflow Theory to Wind Turbine Rotors
,” Ph.D. thesis, Department of Mechanical Engineering, University of Utah, Salt Lake City, UT.
11.
Laino
,
D. J.
, and
Hansen
,
A. C.
,
2004
, “
Current Efforts Towards Improved Aerodynamic Modeling Using the AeroDyn Subroutines
,”
AIAA
Paper No. 2004-0826.
12.
Sant
,
T.
,
van Kuik
,
G. A. M.
, and
van Bussel
,
G. J. W.
,
2009
, “
Estimating the Angle of Attack From Blade Pressure Measurements on the NREL Phase VI Rotor Using a Free-Wake Vortex Model: Yawed Conditions
,”
Wind Energy
,
12
(
1
), pp.
1
32
.
13.
Qiu
,
Y. X.
,
Wang
,
X. D.
,
Kang
,
S.
,
Zhao
,
M.
, and
Liang
,
J. Y.
,
2014
, “
Predictions of Unsteady HAWT Aerodynamics in Yawing and Pitching Using the Free Vortex Method
,”
Renewable Energy
,
70
, pp.
93
106
.
14.
Matha
,
D.
,
Schlipf
,
M.
,
Cordle
,
A.
,
Pereira
,
R.
, and
Jonkman
,
J.
,
2011
, “
Challenges in Simulation of Aerodynamics, Hydrodynamics, and Mooring-Line Dynamics of Floating Offshore Wind Turbines
,”
21st International Offshore and Polar Engineering Conference
,
Maui, HI
, June 19–24, Paper No.
NREL
/CP-5000-50544.
15.
Sebastian
,
T.
, and
Lackner
,
M. A.
,
2012
, “
Development of a Free-Wake Vortex Method Code for Offshore Floating Wind Turbines
,”
Renewable Energy
,
46
, pp.
269
275
.
16.
Sebastian
,
T.
, and
Lackner
,
M. A.
,
2013
, “
Characterization of the Unsteady Aerodynamics of Offshore Floating Wind Turbines
,”
Wind Energy
,
16
(
3
), pp.
339
352
.
17.
Jeon
,
M.
,
Lee
,
S.
, and
Lee
,
S.
,
2014
, “
Unsteady Aerodynamics of Offshore Floating Wind Turbines in Platform Pitching Motion Using the Vortex Lattice Method
,”
Renewable Energy
,
65
, pp.
207
212
.
18.
Farrugia
,
R.
,
Sant
,
T.
, and
Micallef
,
D.
,
2014
, “
Investigating the Aerodynamic Performance of a Model Offshore Floating Wind Turbine
,”
Renewable Energy
,
70
, pp.
24
30
.
19.
Sant
,
T.
,
Bonnici
,
D.
,
Farrugia
,
R.
, and
Micallef
,
D.
,
2014
, “
Measurements and Modelling of the Power Performance of a Model Floating Wind Turbine Under Controlled Conditions
,”
Wind Energy
,
18
(
5
), pp.
811
834
.
20.
Xu
,
B. F.
,
Wang
,
T. G.
, and
Cao
,
J. F.
,
2015
, “
Unsteady Aerodynamics Analysis of Offshore Floating Wind Turbines Under Different Wind Conditions
,”
Phil. Trans. R. Soc. A
,
373
(2035), p.
20140080
.
21.
de Vaal
,
J. B.
,
Hansen
,
M. O. L.
, and
Moan
,
T.
,
2014
, “
Effect of Wind Turbine Surge Motion on Rotor Thrust and Induced Velocity
,”
Wind Energy
,
17
(
1
), pp.
105
121
.
22.
Tran
,
T. T.
, and
Kim
,
D. H.
,
2015
, “
The Platform Pitching Motion of Floating Offshore Wind Turbine: A Preliminary Unsteady Aerodynamic Analysis
,”
J. Wind Eng. Ind. Aerodyn., Energies
,
142
, pp.
65
81
.
23.
Micallef
,
D.
, and
Sant
,
T.
,
2015
, “
Loading Effects on Floating Offshore Horizontal Axis Wind Turbines in Surge Motion
,”
Renewable Energy
,
83
, pp.
737
748
.
24.
Rockel
,
S.
,
Camp
,
E.
,
Schmidt
,
J.
,
Peinke
,
J.
,
Cal
,
R. B.
, and
Holling
,
M.
,
2014
, “
Experimental Study on Influence of Pitch Motion on the Wake of a Floating Wind Turbine Model
,”
Energies
,
7
(
4
), pp.
1954
1985
.
25.
Bayati
,
I.
,
Belloli
,
M.
, and
Facchinetti
,
A.
,
2013
, “
Wind Tunnel Tests on Floating Offshore Wind Turbines: A Proposal for Hardware-in-the-Loop Approach to Validate Numerical Codes
,”
Wind Eng.
,
37
(
6
), pp.
557
568
.
26.
Bayati
,
I.
,
Belloli
,
M.
,
Ferrari
,
D.
,
Fossati
,
F.
, and
Giberti
,
H.
,
2014
, “
Design of a 6-DoF Robotic Platform for Wind Tunnel Tests of Floating Wind Turbines
,”
Energy Procedia
,
53
, pp.
313
323
.
27.
Jonkman
,
J. M.
, and
Buhl
,
M. L.
, Jr.
,
2005
, “
FAST User's Guide
,”
National Renewable Energy Laboratory
,
Golden, CO
.
28.
Jonkman
,
J. M.
,
2007
, “
Dynamics Modelling and Loads Analysis of an Offshore Floating Wind Turbine
,” National Renewable Energy Laboratory, Golden, CO, Report No. NREL/TP-500-41958.
29.
Jonkman
,
J.
,
Butterfield
,
S.
,
Musial
,
W.
, and
Scott
,
G.
,
2009
, “
Definition of a 5-MW Reference Wind Turbine for Offshore System Development
,” National Renewable Energy Laboratory, Golden, CO, Report No. NREL/TP-500-38060.
30.
Matha
,
D.
,
Jonkman
,
J.
, and
Fischer
,
T.
,
2010
, “
Model Development and Loads Analysis of an Offshore Wind Turbine on a Tension Leg Platform, With a Comparison to Other Floating Turbine Concepts
,” National Renewable Energy Laboratory, Golden, CO, Report No. NREL/SR-500-45891.
31.
Moriarty
,
P. J.
, and
Hansen
,
A. C.
,
2005
, “
AeroDyn Theory Manual
,” National Renewable Energy Laboratory, Golden, CO, Report No. NREL/EL-500-36881.
32.
Ramasamy
,
M.
, and
Leishman
,
J. G.
,
2005
, “
A Reynolds Number-Based Blade Tip Vortex Model
,”
J. Am. Helicopter Soc.
,
52
(
3
), pp.
214
223
.
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