The aerodynamics of a wind turbine is governed by the flow around the rotor, where the prediction of air loads on rotor blades in different operational conditions and its relation to rotor structural dynamics is one of the most important challenges in wind turbine rotor blade design. Because of the unsteady flow field around wind turbine blades, prediction of aerodynamic loads with high level of accuracy is difficult and increases the uncertainty of load calculations. An in-house vortex lattice free wake (VLFW) code, based on the inviscid, incompressible, and irrotational flow (potential flow), was developed to study the aerodynamic loads. Since it is based on the potential flow, it cannot be used to predict viscous phenomena such as drag and boundary layer separation. Therefore, it must be coupled to tabulated airfoil data to take the viscosity effects into account. Additionally, a dynamic approach must be introduced to modify the aerodynamic coefficients for unsteady operating conditions. This approach, which is called dynamic stall, adjusts the lift, the drag, and the moment coefficients for each blade element on the basis of the two-dimensional (2D) static airfoil data together with the correction for separated flow. Two different turbines, NREL and MEXICO, are used in the simulations. Predicted normal and tangential forces using the VLFW method are compared with the blade element momentum (BEM) method, the GENUVP code, and the MEXICO wind tunnel measurements. The results show that coupling to the 2D static airfoil data improves the load and power predictions while employing the dynamic stall model to take the time-varying operating conditions into consideration is crucial.

References

References
1.
Hansen
,
M. O.
,
2008
,
Aerodynamics of Wind Turbines
,
2nd ed.
,
EarthScan
,
London
.
2.
van Garrel
,
A.
,
2003
, “
Development of a Wind Turbine Aerodynamics Simulation Module
,” Energy Research Centre of the Netherlands (ECN), Petten, The Netherlands, Report No.
ECN-C–03-079
.
3.
Vermeer
,
L.
,
Sørensen
,
J.
, and
Crespo
,
A.
,
2003
, “
Wind Turbine Wake Aerodynamics
,”
Prog. Aerosp. Sci.
,
39
(
6–7
), pp.
467
510
.
4.
Opoku
,
D. G.
,
Triantos
,
D. G.
,
Nitzsche
,
F.
, and
Voutsinas
,
S. G.
,
2002
, “
Rotorcraft Aerodynamic and Aeroacoustic Modeling Using Vortex Particle Methods
,” 23rd International Congress of the Aeronautical Sciences (
ICAS
), Toronto, ON, Canada, Sept. 8–13, Paper No. ICAS 2002-2.1.3.
5.
Voutsinas
,
S. G.
,
Beleiss
,
M. A.
, and
Rados
,
K. G.
,
1995
, “
Investigation of the Yawed Operation of Wind Turbines by Means of a Vortex Particle Method
,”
AGARD
Conference Proceedings
, Vol.
552
, pp.
11.1
11
.
6.
Zhao
,
J.
, and
He
,
C.
,
2010
, “
A Viscous Vortex Particle Model for Rotor Wake and Interference Analysis
,”
J. Am. Helicopter Soc.
,
55
(
1
), p.
12007
.
7.
Egolf
,
T. A.
,
1988
, “
Helicopter Free Wake Prediction of Complex Wake Structures Under Blade-Vortex Interaction Operating Conditions
,”
44th Annual Forum of the American Helicopter Society
, Washington, DC, June 16–18, pp.
819
832
.
8.
Rosen
,
A.
, and
Graber
,
A.
,
1988
, “
Free Wake Model of Hovering Rotors Having Straight or Curved Blades
,”
J. Am. Helicopter Soc.
,
33
(
3
), pp.
11
21
.
9.
Bagai
,
A.
,
1995
, “
Contribution to the Mathematical Modeling of Rotor Flow-Fields Using a Pseudo-Implicit Free Wake Analysis
,” Ph.D. thesis, University of Maryland, College Park, MD.
10.
Gupta
,
S.
,
2006
, “
Development of a Time-Accurate Viscous Lagrangian Vortex Wake Model for Wind Turbine Applications
,”
Ph.D. thesis
, University of Maryland, College Park, MD.
11.
Pesmajoglou
,
S.
, and
Graham
,
J.
,
2000
, “
Prediction of Aerodynamic Forces on Horizontal Axis Wind Turbines in Free Yaw and Turbulence
,”
J. Wind Eng. Ind. Aerodyn.
,
86
(
1
), pp.
1
14
.
12.
Voutsinas
,
S.
,
2006
, “
Vortex Methods in Aeronautics: How To Make Things Work
,”
Int. J. Comput. Fluid Dyn.
,
20
(
1
), pp.
3
18
.
13.
Chattot
,
J.
,
2007
, “
Helicoidal Vortex Model For Wind Turbine Aeroelastic Simulation
,”
Comput. Struct.
,
85
(
11–14
), pp.
1072
1079
.
14.
Chattot
,
J.
,
2003
, “
Optimization of Wind Turbines Using Helicoidal Vortex Model
,”
ASME J. Sol. Energy Eng.
,
125
(
4
), pp.
418
424
.
15.
Holierhoek
,
J.
,
de Vaal
,
J.
,
van Zuijlen
,
A.
, and
Bijl
,
H.
,
2013
, “
Comparing Different Dynamic Stall Models
,”
J. Wind Energy
,
16
(
1
), pp.
139
158
.
16.
Leishman
,
J.
,
2002
, “
Challenges in Modeling the Unsteady Aerodynamics of Wind Turbines
,”
AIAA
Paper No. 2002-0037.
17.
Bierbooms
,
W.
,
1992
, “
A Comparison Between Unsteady Aerodynamic Models
,”
J. Wind Eng. Ind. Aerodyn.
,
39
(
1–3
), pp.
23
33
.
18.
Schepers
,
J.
, and
Boorsma
,
K.
,
2006
, “
Description of Experimental Setup MEXICO Measurements
,” Energy Research Centre of the Netherlands (ECN), Petten, The Netherlands, Report No. ECN-X–09-0XX.
19.
Anderson
,
J.
,
2001
,
Fundamentals of Aerodynamics
,
3rd ed.
,
McGraw-Hill
,
New York
.
20.
van Garrel
,
A.
,
2001
, “
Requirements for a Wind Turbine Aerodynamics Simulation Module
,” 1st ed., Energy Research Centre of the Netherlands (ECN), Petten, The Netherlands, Report No.
ECN-C–01-099
.
21.
Leishman
,
J.
, and
Bagai
,
M. J.
,
2002
, “
Free Vortex Filament Methods for the Analysis of Helicopter Rotor Wakes
,”
J. Aircr.
,
39
(
5
), pp.
759
775
.
22.
Bhagwat
,
M.
, and
Leishman
,
J.
,
2002
, “
Generalized Viscous Vortex Model for Application to Free-Vortex Wake and Aeroacoustic Calculations
,”
58th Annual Forum and Technology Display of the American Helicopter Society International
, Montreal, Canada, June 11–13, pp. 2042–2057.
23.
Vasitas
,
G.
,
Kozel
,
V.
, and
Mih
,
W.
,
1991
, “
A Simpler Model for Concentrated Vortices
,”
Exp. Fluids
,
11
(
1
), pp.
73
76
.
24.
Bagai
,
A.
, and
Leishman
,
J.
,
1993
, “
Flow Visualization of Compressible Vortex Structures Using Density Gradient Techniques
,”
Exp. Fluids
,
15
(
6
), pp.
431
442
.
25.
Katz
,
J.
, and
Plotkin
,
A.
,
2001
,
Low-Speed Aerodynamics
,
2nd ed.
,
Cambridge University Press
,
New York
.
26.
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
.
27.
Abedi
,
H.
,
2013
, “
Development of Vortex Filament Method for Aerodynamic Loads on Rotor Blades
,”
Licentiate thesis
, Chalmers University of Technology, Gothenburg, Sweden.
28.
Chasapogiannis
,
P.
, and
Voutsinas
,
S.
,
2014
, “
Aerodynamic Simulations of the Flow Around a Horizontal Axis Wind Turbine Using the GAST Software
,” National Technical University of Athens, Athens, Greece, Ref. No. 68/1110 (in Greek).
29.
Abedi
,
H.
,
Davidson
,
L.
, and
Voutsinas
,
S.
,
2015
, “
Numerical Studies of the Upstream Flow Field Around a Horizontal Axis Wind Turbine
,”
AIAA
Paper No. 2015-0495.
30.
Reddy
,
T. S. R.
, and
Kaza
,
K. R. V.
,
1989
, “
Analysis of an Unswept Propfan Blade With a Semi Empirical Dynamic Stall Model
,” NASA Lewis Research Center, Cleveland, OH, Report No.
NASA-TM-4083
.
You do not currently have access to this content.