National Renewable Energy Laboratory, USA (NREL) airfoils have been specially developed for wind turbine applications, and projected to yield more annual energy without increasing the maximum power level. These airfoils are designed to have a limited maximum lift and relatively low sensitivity to leading-edge roughness. As a result, these airfoils have quite different leading-edge profiles from airfoils applied to helicopter blades, and thus, quite different dynamic-stall characteristics. Unfortunately for wind turbine aerodynamics, the dynamic-stall models in use are still those specially developed and refined for helicopter applications. A good example is the Leishman–Beddoes dynamic-stall model, which is one of the most popular models in wind turbine applications. The consequence is that the application of such dynamic-stall model to low-speed cases can be problematic. Recently, some specific dynamic-stall models have been proposed or tuned for the cases of low Mach numbers, but their universality needs further validation. This paper considers the application of the modified dynamic low-speed stall model of Sheng et al. (“A Modified Dynamic Stall Model for Low Mach Numbers,” 2008, ASME J. Sol. Energy Eng., 130(3), pp. 031013) to the NREL airfoils. The predictions are compared with the data of the NREL airfoils tested at the Ohio State University. The current research has two objectives: to justify the suitability of the low-speed dynamic-stall model, and to provide the relevant parameters for the NREL airfoils.

1.
Harris
,
F. D.
, and
Pruyn
,
R. R.
, 1968, “
Blade Stall—Half Fact, Half Fiction
,”
J. Am. Helicopter Soc.
0002-8711,
13
(
2
), pp.
27
48
.
2.
Ham
,
N. D.
, and
Garelick
,
M. S.
, 1968, “
Dynamic Stall Considerations in Helicopter Rotors
,”
J. Am. Helicopter Soc.
0002-8711,
13
(
2
), pp.
49
55
.
3.
McCroskey
,
W. J.
, 1976, “
Dynamic Stall Experiments on Oscillating Airfoils
,”
AIAA J.
0001-1452,
14
, pp.
57
63
.
4.
McAlister
,
K. W.
,
Carr
,
L. W.
, and
McCroskey
,
W. J.
, 1978, “
Dynamic Stall Experiments on the NACA 0012 Airfoil
,”
NASA
Technical Paper No. 1100.
5.
Wilby
,
P. G.
, 1980, “
The Aerodynamic Characteristics of Some New RAE Blade Sections, and Their Potential Influence on Rotor Performance
,”
Vertica
0360-5450,
4
, pp.
121
133
.
6.
McCroskey
,
W. J.
,
McAlister
,
K. W.
,
Carr
,
L. W.
,
Pucci
,
S. L.
,
Lambert
,
O.
, and
Indergrand
,
R. F.
, 1981, “
Dynamic Stall on Advanced Airfoil Sections
,”
J. Am. Helicopter Soc.
0002-8711,
26
, pp.
40
50
.
7.
Gross
,
D. W.
, and
Harris
,
F. D.
, 1969, “
Prediction of In-Flight Stalled Airloads From Oscillating Airfoil Data
,”
Proceedings of the 25th Annual Forum of the American Helicopter Society
, Washington, DC, May 14–16.
8.
Johnson
,
W.
, 1969, “
The Effect of Dynamic Stall on the Response and Airloading of Helicopter Rotor Blades
,”
J. Am. Helicopter Soc.
0002-8711,
14
(
2
), pp.
68
77
.
9.
Bielawa
,
R. L.
, 1975, “
Synthesized Unsteady Airfoil Data With Applications to Stall Flutter Calculation
,”
Proceedings of the 31st Annual Forum of the American Helicopter Society
, Washington, DC, May 13–15.
10.
Tran
,
C. T.
, and
Pitot
,
D.
, 1981, “
Semi-Empirical Model for the Dynamic Stall of Airfoils in View of the Application to the Calculation of the Response of a Helicopter Blade in Forward Flight
,”
Vertica
0360-5450,
5
(
1
), pp.
35
53
.
11.
Beddoes
,
T. S.
, 1983, “
Representation of Airfoil Behaviour
,”
Vertica
0360-5450,
7
(
2
), pp.
183
197
.
12.
Beddoes
,
T. S.
, 1984, “
Practical Computational of Unsteady Lift
,”
Vertica
0360-5450,
8
(
1
), pp.
55
71
.
13.
Gangwani
,
S. T.
, 1982, “
Prediction of Dynamic Stall and Unsteady Airloads on Rotor Blades
,”
J. Am. Helicopter Soc.
0002-8711,
27
(
4
), pp.
57
64
.
14.
Gangwani
,
S. T.
, 1984, “
Synthesized Airfoil Data Method for Prediction of Dynamic Stall and Unsteady Airloads
,”
Vertica
0360-5450,
8
(
2
), pp.
93
118
.
15.
Leishman
,
J. G.
, and
Beddoes
,
T. S.
, 1989, “
A Semi-Empirical Model for Dynamic Stall
,”
J. Am. Helicopter Soc.
0002-8711,
34
(
3
), pp.
3
17
.
16.
Ekaterinaris
,
J. A.
, and
Platzer
,
M. F.
, 1998, “
Computational Prediction of Airfoil Dynamic Stall
,”
Prog. Aerosp. Sci.
0376-0421,
33
, pp.
759
846
.
17.
Wolfe
,
W. P.
, and
Ochs
,
S. S.
, 1997, “
CFD Calculations of S809 Aerodynamic Characteristics
,” Paper No. AIAA-97-0973.
18.
Guilmineau
,
E.
, and
Queutey
,
P.
, 1999, “
Numerical Study of Dynamic Stall on Several Airfoil Sections
,”
AIAA J.
0001-1452,
37
, pp.
128
130
.
19.
Spentzos
,
A.
,
Barakos
,
G. N.
,
Badcock
,
K. J.
,
Richards
,
B. E.
,
Wernert
,
P.
,
Schreck
,
S.
, and
Raffel
,
M.
, 2005, “
Investigation of Three-Dimensional Dynamic Stall Using Computational Fluid Dynamics
,”
AIAA J.
0001-1452,
43
, pp.
1023
1033
.
20.
Langtry
,
R. B.
,
Gola
,
J.
, and
Menter
,
F. R.
, 2006, “
Prediction 2D Airfoil and 3D Wind Turbine Rotor Performance Using a Transition Model for General CFD Codes
,” Paper No. AIAA-2006-0395.
21.
Galbraith
,
R. A. McD.
,
Gracey
,
M. W.
, and
Leitch
,
E.
, 1992, “
Summary of Pressure Data for Thirteen Aerofoils on the University of Glasgow Aerofoil Database
,” GU Aero Report No. 9221,
University of Glasgow
.
22.
Ramsay
,
R. R.
,
Hoffmann
,
M. J.
, and
Gregorek
,
G. M.
, 1996, “
Effects of Grit Roughness and Pitch Oscillations on the S801 Airfoil
,” Report No. NREL/TP-442-7818.
23.
Ramsay
,
R. R.
,
Hoffmann
,
M. J.
, and
Gregorek
,
G. M.
, 1995, “
Effects of Grit Roughness and Pitch Oscillations on the S809 Airfoil
,” Report No. NREL/TP-442-7817.
24.
Ramsay
,
R. R.
,
Hoffmann
,
M. J.
, and
Gregorek
,
G. M.
, 1996, “
Effects of Grit Roughness and Pitch Oscillations on the S810 Airfoil
,” Report No. NREL/TP-442-7816.
25.
Ramsay
,
R. R.
, and
Gregorek
,
G. M.
, 1998, “
Effects of Grit Roughness and Pitch Oscillations on the S812 Airfoil
,” Report No. NREL/TP-440-8167.
26.
Ramsay
,
R. R.
, and
Gregorek
,
G. M.
, 1996, “
Effects of Grit Roughness and Pitch Oscillations on the S813 Airfoil
,” Report No. NREL/TP-442-8168.
27.
Janiszewska
,
J. M.
,
Ramsay
,
R. R.
,
Hoffmann
,
M. J.
, and
Gregorek
,
G. M.
, 1996, “
Effects of Grit Roughness and Pitch Oscillations on the S814 Airfoil
,” Report No. NREL/TP-442-8161.
28.
Ramsay
,
R. R.
,
Hoffmann
,
M. J.
, and
Gregorek
,
G. M.
, 1996, “
Effects of Grit Roughness and Pitch Oscillations on the S815 Airfoil
,” Report No. NREL/TP-442-7820.
29.
Ramsay
,
R. R.
, and
Gregorek
,
G. M.
, 1998, “
Effects of Grit Roughness and Pitch Oscillations on the S824 Airfoil
,” http://wind.nrel.gov/OSU_data/reports/http://wind.nrel.gov/OSU_data/reports/
30.
Ramsay
,
R. R.
,
Hoffmann
,
M. J.
, and
Gregorek
,
G. M.
, 1998, “Effects of Grit Roughness and Pitch Oscillations on the S825 Airfoil,” http://wind.nrel.gov/OSU_data/reports/http://wind.nrel.gov/OSU_data/reports/
31.
Bousman
,
W. G.
, 1998, “
A Qualitative Examination of Dynamic Stall from Flight Test Data
,”
J. Am. Helicopter Soc.
0002-8711,
43
, pp.
279
295
.
32.
Bousman
,
W. G.
, 2000, “
Evaluation of Airfoil Dynamic Stall Characteristics for Maneuverability
,”
Proceedings of the 26th European Rotorcraft Forum
, The Hague, Netherlands, Sept. 26–29.
33.
Fujisawa
,
N.
, and
Shibuya
,
S.
, 2001, “
Observations of Dynamic Stall on Darrieus Wind Turbine Blades
,”
J. Wind Eng. Ind. Aerodyn.
,
89
, pp.
201
214
.
34.
Wilby
,
P. G.
, 2001, “
The Development of Rotor Airfoil Testing in the UK
,”
J. Am. Helicopter Soc.
0002-8711,
46
, pp.
210
220
.
35.
Lee
,
T.
, and
Gerontakos
,
P.
, 2004, “
Investigation of Flow Over an Oscillating Airfoil
,”
J. Fluid Mech.
0022-1120,
512
, pp.
313
341
.
36.
Coton
,
F. N.
,
Wang
,
T.
, and
Galbraith
,
R. A. McD.
, 2002, “
An Examination of Key Aerodynamic Modelling Issues Raised by the NREL Blind Comparison
,”
Wind Energy
1095-4244,
5
(
2–3
), pp.
199
212
.
37.
Niven
,
A. J.
, and
Galbraith
,
R. A. McD.
, 1997, “
Modelling Dynamic Stall Vortex Inception at Low Mach Numbers
,”
Aeronaut. J.
0001-9240,
101
, pp.
67
76
.
38.
Sheng
,
W.
,
Galbraith
,
R. A. McD.
, and
Coton
,
F. N.
, 2006, “
A New Stall-Onset Criterion for Low Speed Dynamic-Stall
,”
ASME J. Sol. Energy Eng.
0199-6231,
128
(
4
), pp.
461
471
.
39.
Sheng
,
W.
,
Galbraith
,
R. A. McD.
, and
Coton
,
F. N.
, 2007, “
Improved Dynamic Stall Onset Criterion at Low Mach Numbers
,”
J. Aircr.
0021-8669,
44
(
3
), pp.
1049
1052
.
40.
Sheng
,
W.
,
Galbraith
,
R. A. McD.
, and
Coton
,
F. N.
, 2007, “
On the Return From Aerofoil Stall During Ramp-Down Pitching Motions
,”
J. Aircr.
0021-8669,
44
(
6
), pp.
1856
1864
.
41.
Gutpa
,
S.
, and
Leishman
,
J. G.
, 2006, “
Dynamic Stall Modelling of the S809 Airfoil and Comparison With Experiments
,” Paper No. AIAA-2006-0196.
42.
Sheng
,
W.
,
Galbraith
,
R. A. McD.
, and
Coton
,
F. N.
, 2008, “
A Modified Dynamic Stall Model for Low Mach Numbers
,”
J. Sol. Energy Eng.
0199-6231,
130
(
3
), p.
031013
.
43.
Beddoes
,
T. S.
, 1989, “
Two and Three Dimensional Indicial Methods for Rotor Dynamic Airloads
,”
Proceedings of the AHS/National Specialists Meeting on Rotorcraft Dynamics
, Arlington, TX.
44.
Sheng
,
W.
,
Galbraith
,
R. A. McD.
, and
Coton
,
F. N.
, 2008, “
Prediction of Dynamic Stall Onset for Oscillatory Low-Speed Aerofoils
,”
ASME J. Fluids Eng.
0098-2202,
130
, pp.
101204
.
45.
Tangler
,
J. L.
, and
Somers
,
D. M.
, 1995, “
NREL Airfoil Families for HAWTs
,”
NREL
Report No. NREL/TP-442-7109.
46.
Somers
,
D. M.
, 1997, “
Design and Experimental Results for the S809 Airfoil
,”
NREL
Report No. NREL/SR-400-6918.
47.
Sheng
,
W.
,
Galbraith
,
R. A. McD.
, and
Coton
,
F. N.
, “
An Experimental Investigation of the S809 Aerofoil Unsteady Characteristics
,”
Wind Energy
1095-4244 (to be published).
48.
Simms
,
D. A.
,
Hand
,
M. M.
,
Fingersh
,
L. J.
, and
Jager
,
D. W.
, 1999, “
Unsteady Aerodynamics Experiment Phases II-IV Test Configurations and Available Data Campaigns
,”
NREL
Report No. NREL/TP-500-29955.
49.
Hand
,
M. M.
,
Simms
,
D. A.
,
Fingersh
,
L. J.
,
Jager
,
D. W.
,
Cotrell
,
J. R.
,
Schreck
,
S.
, and
Larwood
,
S. M.
, 2001, “
Unsteady Aerodynamics Experiment Phase VI: Wind Tunnel Test Configurations and Available Data Campaigns
,”
NREL
Report No. NREL/TP-500-25950.
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