This paper presents the first results of a wide experimental investigation on the aerodynamics of a vertical axis wind turbine. Vertical axis wind turbines have recently received particular attention, as interesting alternative for small and micro generation applications. However, the complex fluid dynamic mechanisms occurring in these machines make the aerodynamic optimization of the rotors still an open issue and detailed experimental analyses are now highly recommended to convert improved flow field comprehensions into novel design techniques. The experiments were performed in the large-scale wind tunnel of the Politecnico di Milano (Italy), where real-scale wind turbines for micro generation can be tested in full similarity conditions. Open and closed wind tunnel configurations are considered in such a way to quantify the influence of model blockage for several operational conditions. Integral torque and thrust measurements, as well as detailed aerodynamic measurements were carried out to characterize the 3D flow field downstream of the turbine. The local unsteady flow field and the streamwise turbulent component, both resolved in phase with the rotor position, were derived by hot wire measurements. The paper critically analyses the models and the correlations usually applied to correct the wind tunnel blockage effects. Results highlight that the presently available theoretical correction models do not provide accurate estimates of the blockage effect in the case of vertical axis wind turbines. The tip aerodynamic phenomena, in particular, seem to play a key role for the prediction of the turbine performance; large-scale unsteadiness is observed in that region and a simple flow model is used here to explain the different flow features with respect to horizontal axis wind turbines.

References

References
1.
Mertens
,
S.
,
van Kuik
,
G.
, and
van Bussel
,
G.
, 2003, “
Performance of a H-Darrieus in the Skewed Flow on a Roof
,”
ASME J. Sol. Energy Eng.
,
125
, pp.
433
440
.
2.
van Bussel
,
G. J. W.
,
Mertens
,
S.
,
Polinder
,
H.
, and
Sidler
,
H. F. A.
, 2004, “
TURBY®: Concept and Realisation of a Small VAWT for the Built Environment
,” The Science of making Torque from Wind, 19–21 April, Delft.
3.
Battisti
,
L.
,
Brighenti
,
A.
, and
Zanne
,
L.
, 2009, “
Analisi dell’effetto della scelta dell’architettura palare sulle prestazioni di turbine eoliche ad asse verticale
,” Atti del 64° Congresso Nazionale ATI.
4.
Paraschivoiu
,
I.
, 2002,
Wind Turbine Design—With Emphasis on Darrieus Concept
(
Polytechnic International Press
,
Montreal
, 2002).
5.
Dixon
,
K.
,
Simao Ferreira
,
C. J.
,
Hofemann
,
C.
,
Van Bussel
,
G. J. W.
, and
Van Kuik
,
G. A. M.
, 2008, “
A 3D Unsteady Panel Method for Vertical Axis Wind Turbines
,”
Proceedings of EWEC Brussels
.
6.
Oler
,
J. W.
,
Strickland
,
J. H.
,
Im
,
B. J.
, and
Graham
,
G. H.
, 1983, “
Dynamic Stall Regulation of the Darrieus Turbine
,” Sandia National Laboratories, Albuquerque, New Mexico, SAND83–7029.
7.
Allet
,
A.
, and
Paraschivoiu
,
I.
, 1995, “
Viscous Flow and Dynamic Stall Effects on Vertical-Axis Wind Turbines
,”
Int. J. Rotating Mach.
,
2
(
1
), pp.
1
14
.
8.
Shen
,
W. Z.
,
Zhang
,
J. H.
, and
Sørensen
,
J. N.
, 2009, “
The Actuator Surface Model: A New Navier–Stokes Based Model for Rotor Computations
,”
ASME J. Sol. Energy Eng.
,
131
,
p.
011002
.
9.
Blackwell
,
B. F.
,
Sheldal
,
R. E.
, and
Feltz
,
L. V.
, 1976, “
Wind Tunnel Performance Data for the Darrieus Wind Turbine With NACA0012 Blades
,” Sandia National Laboratories, Albuquerque, New Mexico, SAND76–0130.
10.
Fujisawa
,
N.
, and
Shibuya
,
S.
, 2001, “
Observations of Dynamic Stall on Darrieus Wind Turbine Blades
,”
J. Wind. Eng. Ind. Aerodyn.
,
89
(
2
), pp.
201
214
.
11.
Simao Ferreira
,
C. J.
,
van Bussel
,
G. J. W.
,
Scarano
,
F.
, and
van Kuik
,
G.
, 2007, “
2D PIV Visualization of Dynamic Stall on a Vertical Axis Wind Turbine
Proceedings of the AIAA/ASME Wind Energy Symposium
.
12.
Hofemann
,
C.
,
Simao Ferreira
,
C. J.
,
Van Bussel
,
G. J. W.
,
van Kuik
,
G. A. M.
,
Scarano
,
F.
, and
Dixon
,
K. R.
, 2008, “
3D Stereo PIV Study of Tip Vortex Evolution on a VAWT
,”
Proceedings of EWEC, Brussels
.
13.
Simao Ferreira
,
C. J.
,
van Kuik
,
G.
, and
van Bussel
,
G.
, 2006, “
Wind tunnel hotwire measurements, flow visualization and thrust measurement of a VAWT in skew
,”
Proceedings of the AIAA/ASME Wind Energy Symposium
.
14.
Sørensen
,
J. N
,
Shen
,
W. Z.
, and
Mikkelsen
,
R.
, 2006, “
Wall Correction Model for Wind Tunnels With Open Test Section
,”
AIAA J.
,
44
(
8
), pp.
1890
1894
.
15.
Mikkelsen
,
R.
, and
Sørensen
,
J. N.
, 2002, “
Modelling of Wind Tunnel Blockage
,”
Proceedings of the Global Windpower Conference and Exhibition
.
16.
Maskell
,
E. C.
, 1963, “
A Theory of the Blockage Effects on Bluff Bodies and Stalled Wings in an Enclosed Wind Tunnel
,” ARC/R & M–3400.
17.
Mercker
,
E.
, and
Wiedemann
,
J.
, 1996, “
On the Correction of the Interference Effects in Open Jet Wind Tunnels
,” SAE Paper No. 960671.
18.
Glauert
,
H.
, 1947,
The Elements of Aerofoil and Airscrew Theory
,
2nd ed.
,
Cambridge University
,
Cambridge, England
.
19.
Loeffler
,
A. L.
, Jr.
, and
Steinhoff
,
J. S.
, 1985, “
Computation of Wind Tunnel Wall Effects in Ducted Rotor Experiments
,”
J. Aircr.
,
22
(
3
), pp
188
192
.
20.
Barlow
,
J. B.
,
Rae
,
W. H.
, and
Pope
,
A.
, 1999,
Low Speed Wind Tunnel Testing
,
3rd ed.
,
John Wiley and Sons Inc.
,
New York
.
21.
Fitzgerald
,
R. E.
, 2007, “
Wind Tunnel Blockage Corrections for Propellers
,” MS thesis, University of Maryland, College Park, MD.
22.
Hansen
,
M. O. L.
, 2000,
Aerodynamics of Wind Turbines
,
James and James Publishing
,
London
.
You do not currently have access to this content.