WIND ENERGY
Wind Energ. (2012)
Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/we.1562
RESEARCH ARTICLE
Effect of wind turbine surge motion on rotor thrust
and induced velocity
J. B. de Vaal
1,2
, M. O. L. Hansen
2,3
and T. Moan
1,2
1
Department of Marine Technology, Norwegian University of Science and Technology, Trondheim, Norway
2
Centre for Ships and Ocean Structures, Department of Marine Technology,Norwegian University of Science and Technology,
Trondheim, Norway
3
DTU Wind Energy, Department of Mechanical Engineering, Technical University of Denmark, Lyngby, Denmark
ABSTRACT
Offshore wind turbines on floating platforms will experience larger motions than comparable bottom fixed wind turbines—
for which the majority of industry standard design codes have been developed and validated. In this paper, the effect of a
periodic surge motion on the integrated loads and induced velocity on a wind turbine rotor is investigated. Specifically, the
performance of blade element momentum theory with a quasisteady wake as well as two widely used engineering dynamic
inflow models is evaluated. A moving actuator disc model is used as reference, since the dynamics associated with the
wake will be inherently included in the solution of the associated fluid dynamic problem. Through analysis of integrated
rotor loads, induced velocities and aerodynamic damping, it is concluded that typical surge motions are sufficiently slow to
not affect the wake dynamics predicted by engineering models significantly. Copyright © 2012 John Wiley & Sons, Ltd.
KEYWORDS
dynamic inflow; actuator disc; floating wind turbine; surge motion; aerodynamic damping
Correspondence
J. B. de Vaal, Centre for Ships and Ocean Structures, Marine Technology Centre, NO-7491 Trondheim, Norway.
E-mail: jacobus.b.de.vaal@ntnu.no
Received 27 April 2012; Revised 05 August 2012; Accepted 07 September 2012
NOMENCLATURE
Notations
a axial induction factor (–)
A rotor area (m
2
)
c chord
C
D
section drag coefficient (–)
C
L
section lift coefficient (–)
C
T
thrust coefficient (–)
D drag per unit span (N m
1
)
f force per unit area (N m
2
)
f
0
body force (N m
3
)
F force per unit span (N m
1
)
H
s
significant wave height (m)
k modelling constant (–)
L lift per unit span (N m
1
)
m
a
apparent additional mass (kg)
M
flat
blade flatwise bending moment (Nm)
N
b
number of blades (–)
r radial coordinate (m)
R rotor radius (m)
Copyright © 2012 John Wiley & Sons, Ltd.