An experimental study conducted in a wind tunnel on the mixing of moist air by a scaled wind turbine is presented. The experimental setup allows us to generate stable stratification conditions with respect to relative humidity and temperature in a closed-loop wind tunnel. The flow and its thermodynamic properties were characterized using a Cobra probe (a multi-hole pitot tube) and a sensor of local temperature and relative humidity, both used simultaneously to obtain vertical profiles. The flow and its stratification were measured downstream of a scaled rotor at two different streamwise distances (1 and 10 rotor diameters) and two Reynolds numbers based on the diameter of the wind turbine rotor (22 000 and 44 000, respectively). This was then compared to the inflow conditions. The wake mean structure and the humidity and temperature stratifications of the flow are found to be affected by the presence of the rotor. In particular, the stratification was always smaller one diameter downstream from the model (when compared to the empty test section case), and then was mostly recovered in the far wake (10 diameters downstream). This effect depended not only on the streamwise distance, but also on the Reynolds number of the flow. Finally, the bulk Richardson number Rb was found to be an appropriate parameter to quantify this effect.

1.
J.
Meyers
and
C.
Meneveau
, “
Large eddy simulations of large wind-turbine arrays in the atmospheric boundary layer
,” in
48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition
(
2010
), p.
827
.
2.
R.
Stoll
and
F.
Porté-Agel
, “
Surface heterogeneity effects on regional-scale fluxes in stable boundary layers: Surface temperature transitions
,”
J. Atmos. Sci.
66
,
412
431
(
2009
).
3.
M.
Calaf
,
M. B.
Parlange
, and
C.
Meneveau
, “
Large eddy simulation study of scalar transport in fully developed wind-turbine array boundary layers
,”
Phys. Fluids
23
,
126603
(
2011
).
4.
W.
Yue
,
Y.
Xue
, and
Y.
Liu
, “
High humidity aerodynamic effects study on offshore wind turbine airfoil/blade performance through CFD analysis
,”
Int. J. Rotating Mach.
2017
,
1
.
5.
K. A.
Adkins
and
A.
Sescu
, “
Observations of relative humidity in the near-wake of a wind turbine using an instrumented unmanned aerial system
,”
Int. J. Green Energy
14
,
845
860
(
2017
).
6.
L.
Zhan
,
S.
Letizia
, and
G. V.
Iungo
, “
Optimal tuning of engineering wake models through LIDAR measurements
,”
Wind Energy Sci.
5
,
1601
1622
(
2020
).
7.
G.
Lungo
and
F.
Porte-Agel
, “
Volumetric scanning of wind turbine wakes under convective and neutral stability regimes
,”
J. Atmos. Oceanic Technol.
31
,
2035
2048
(
2014
).
8.
K. S.
Hansen
,
R. J.
Barthelmie
,
L. E.
Jensen
, and
A.
Sommer
, “
The impact of turbulence intensity and atmospheric stability on power deficits due to wind turbine wakes at horns rev wind farm
,”
Wind Energy
15
,
183
196
(
2012
).
9.
D.
Mortley
,
C.
Bonsi
,
P.
Loretan
,
W.
Hill
, and
C.
Morris
, “
Relative humidity influences yield, edible biomass, and linear growth rate of sweetpotato
,”
HortScience
29
,
609
610
(
1994
).
10.
K.
Everard
,
H.
Oldroyd
, and
A.
Christen
, “
Turbulent heat and momentum exchange in nocturnal drainage flow through a sloped vineyard
,”
Boundary-Layer Meteorol.
175
,
1
23
(
2020
).
11.
L. P.
Chamorro
and
F.
Porté-Agel
, “
A wind-tunnel investigation of wind-turbine wakes: Boundary-layer turbulence effects
,”
Boundary-Layer Meteorol.
132
,
129
149
(
2009
).
12.
R.
Scott
,
B.
Viggiano
,
T.
Dib
,
N.
Ali
,
M.
Hölling
,
J.
Peinke
, and
R. B.
Cal
, “
Wind turbine partial wake merging description and quantification
,”
Wind Energy
23
,
1610
1618
(
2020
).
13.
S.
Rockel
,
J.
Peinke
,
M.
Hölling
, and
R. B.
Cal
, “
Dynamic wake development of a floating wind turbine in free pitch motion subjected to turbulent inflow generated with an active grid
,”
Renewable Energy
112
,
1
16
(
2017
).
14.
S.
Rockel
,
E.
Camp
,
J.
Schmidt
,
J.
Peinke
,
R. B.
Cal
, and
M.
Hölling
, “
Experimental study on influence of pitch motion on the wake of a floating wind turbine model
,”
Energies
7
,
1954
1985
(
2014
).
15.
N.
Hamilton
,
H.-S.
Kang
,
C.
Meneveau
, and
R. B.
Cal
, “
Statistical analysis of kinetic energy entrainment in a model wind turbine array boundary layer
,”
J. Renewable Sustainable Energy
4
,
063105
(
2012
).
16.
G. V.
Iungo
, “
Experimental characterization of wind turbine wakes: Wind tunnel tests and wind LIDAR measurements
,”
J. Wind Eng. Ind. Aerodyn.
149
,
35
39
(
2016
).
17.
M.
Bastankhah
and
F.
Porté-Agel
, “
Wind tunnel study of the wind turbine interaction with a boundary-layer flow: Upwind region, turbine performance, and wake region
,”
Phys. Fluids
29
,
065105
(
2017
).
18.
B.
Dou
,
M.
Guala
,
L.
Lei
, and
P.
Zeng
, “
Experimental investigation of the performance and wake effect of a small-scale wind turbine in a wind tunnel
,”
Energy
166
,
819
833
(
2019
).
19.
J.
Bartl
,
F.
Mühle
,
J.
Schottler
,
L.
Saetran
,
J.
Peinke
,
M.
Adaramola
, and
M.
Hölling
, “
Wind tunnel experiments on wind turbine wakes in yaw: Effects of inflow turbulence and shear
,”
Wind Energy Science
3
,
329
343
(
2018
).
20.
P. E.
Hancock
and
F.
Pascheke
, “
Wind-tunnel simulation of the wake of a large wind turbine in a stable boundary layer: Part 2, the wake flow
,”
Boundary-Layer Meteorol.
151
,
23
37
(
2014
).
21.
F.
Campagnolo
,
V.
Petrović
,
J.
Schreiber
,
E. M.
Nanos
,
A.
Croce
, and
C. L.
Bottasso
, “
Wind tunnel testing of a closed-loop wake deflection controller for wind farm power maximization
,”
J. Phys.: Conf. Ser.
753
,
032006
(
2016
).
22.
R. B.
Cal
,
J.
Lebrón
,
L.
Castillo
,
H. S.
Kang
, and
C.
Meneveau
, “
Experimental study of the horizontally averaged flow structure in a model wind-turbine array boundary layer
,”
J. Renewable Sustainable Energy
2
,
013106
(
2010
).
23.
S. E.
Smith
,
K. N.
Travis
,
H.
Djeridi
,
M.
Obligado
, and
R. B.
Cal
, “
Dynamic effects of inertial particles on the wake recovery of a model wind turbine
,”
Renewable Energy
164
,
346
361
(
2021
).
24.
Y.
Odemark
and
J. H.
Fransson
, “
The stability and development of tip and root vortices behind a model wind turbine
,”
Exp. Fluids
54
,
1591
(
2013
).
25.
J.
Schottler
,
A.
Hölling
,
J.
Peinke
, and
M.
Hölling
, “
Design and implementation of a controllable model wind turbine for experimental studies
,”
J. Phys.: Conf. Ser.
753
,
072030
(
2016
).
26.
L. P.
Chamorro
and
F.
Porte-Agel
, “
Turbulent flow inside and above a wind farm: A wind-tunnel study
,”
Energies
4
,
1916
1936
(
2011
).
27.
N.
Hamilton
,
M.
Melius
, and
R. B.
Cal
, “
Wind turbine boundary layer arrays for Cartesian and staggered configurations–Part I: Flow field and power measurements
,”
Wind Energy
18
,
277
295
(
2015
).
28.
S.
Watkins
,
P.
Mousley
, and
J.
Hooper
, “
Measurement of fluctuating flows using multi-hole probes
,” in
Ninth International Congress on Sound and Vibration
(
2002
), pp.
8
11
.
29.
C.
Brun
,
S.
Blein
, and
J.-P.
Chollet
, “
Large-eddy simulation of a katabatic jet along a convexly curved slope. Part II: Statistical results
,”
J. Atmos. Sci.
74
,
4047
4073
(
2017
).
30.
R. B.
Stull
,
An Introduction to Boundary Layer Meteorology
(
Springer Science & Business Media
,
2012
), Vol.
13
.
31.
C. M.
St Martin
,
J. K.
Lundquist
,
A.
Clifton
,
G. S.
Poulos
, and
S. J.
Schreck
, “
Wind turbine power production and annual energy production depend on atmospheric stability and turbulence
,”
Wind Energy Sci.
1
,
221
236
(
2016
).
32.
J.
Kondo
,
O.
Kanechika
, and
N.
Yasuda
, “
Heat and momentum transfers under strong stability in the atmospheric surface layer
,”
J. Atmos. Sci.
35
,
1012
1021
(
1978
).
33.
F.
Nieuwstadt
and
J.
Meeder
, “
Les of air pollution dispersion: A review
,” in
New Tools in Turbulence Modelling
(
Springer
,
Berlin
,
1996
), pp.
265
280
.
You do not currently have access to this content.