A Wells turbine for wave power conversion has hysteretic characteristics in a reciprocating flow. The counterclockwise hysteretic loop of the Wells turbine is opposite to the clockwise one of the well-known dynamic stall of an airfoil. In this paper, the mechanism of the hysteretic behavior was elucidated by an unsteady three-dimensional Navier-Stokes numerical simulation. It was found that the hysteretic behavior was associated with a streamwise vortical flow appearing near the blade suction surface. In the accelerating process of axial flow velocity, the vortex is intensified to enlarge the flow separation area on the blade suction surface. In the decelerating flow process, the flow separation area is reduced because of the weakened vortex. Therefore, the aerodynamic performance in the accelerating flow process is lower than in the decelerating flow process, unlike the dynamic stall. Based on the vortex theorem, the mechanism to vary the intensity of the vortex can be explained by the trailing vortices associated with the change in the blade circulation.

Issue Section:
Technical Papers
Keywords:
turbines, power conversion, hysteresis, Navier-Stokes equations, flow simulation, flow separation, vortices, aerodynamics
Topics:
Blades, Flow (Dynamics), Suction, Turbines, Vortices, Wave energy, Wells, Flow separation, Computer simulation, Wakes
1.
Inoue
,
M.
,
Kaneko
,
K.
,
Setoguchi
,
T.
, and
Simamoto
,
K.
,
1985
, “
Studies on Wells Turbine for Wave Power Generator (4th Report, Starting and Running Characteristics in Periodically Oscillating Flow)
,”
Trans. Jpn. Soc. Mech. Eng., Ser. B
,
51
(
468
), pp.
2746
–
2751
(in Japanese).
2.
Inoue
,
M.
,
Kaneko
,
K.
,
Setoguchi
,
T.
, and
Koura
,
F.
,
1987
, “
Hysteretic Characteristics of Wells Turbine in Reciprocating Flow
,”
Trans. Jpn. Soc. Mech. Eng., Ser. B
,
53
(
496
), pp.
3699
–
3704
(in Japanese).
3.
Setoguchi, T., Kaneko, K., Hamakawa, H., and Inoue, M., 1990, “Measurement of Hysteresis on Wells Turbine Characteristics in Reciprocating Flow,” Proc. 1st International Symposium on Experimental and Computational Aerothermodynamics of Internal Flows, ISECAIF, Beijing, China, pp. 537–543.
4.
Alcorn, R. G., and Beattie, W. C., 1998, “Observations of Time domain Data on Wells Turbine in the Islay Wave-Power Plant,” Proc. 8th International Offshore and Polar Engineering Conference, ISOPE, Cupertino, CA, 1, pp. 81–85.
5.
Ericsson
,
L. E.
, and
Reding
,
J. P.
,
1987
, “
Fluid Dynamics of Unsteady Separated Flow, Part II. Lifting Surfaces
,”
Prog. Aerosp. Sci.
,
24
, pp.
249
–
356
.
6.
Shida
,
Y.
,
Kuwahara
,
K.
,
Ono
,
K.
, and
Takami
,
H.
,
1987
, “
Computation of Dynamic Stall of a NACA-0012 Airfoil
,”
AIAA J.
,
25
(
3
), pp.
408
–
413
.
7.
Carr
,
L. W.
,
1988
, “
Progress in Analysis and Prediction of Dynamic Stall
,”
J. Aircr.
,
25
(
1
), pp.
6
–
17
.
8.
Leishman
,
J. G.
,
1990
, “
Dynamic Stall Experiments on the NACA 23012 Aerofoil
,”
Exp. Fluids
,
9
, pp.
49
–
58
.
9.
Yakhot
,
V.
, and
Orszag
,
S. A.
,
1986
, “
Renormalization Group Analysis of Turbulence (I. Basic Theory)
,”
J. Sci. Comput.
,
1
(
1
), pp.
3
–
51
.
Copyright © 2003
 by ASME
You do not currently have access to this content.