experimental,measurements,and
TRANSCRIPT
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Experimental Measurements and Numerical Simula4ons in a 3-‐Turbine Array of 45:1 Scale DOE RM1 Turbines
Alberto Aliseda!Danny Sale!
Teymour Javaherchi!Nick Stelzenmuller!
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WHAT IS TIDAL ENERGY? Background Design Experiment Single Turbine Results Array Results
LABORATORY-SCALE ROTOR GEOMETRY
I Maximize chord-based Reynoldsnumber
I Choose foil to minimize Reynoldsnumber effects
I Match performance and optimum tipspeed ratio with blade-elementmomentum design code
I Attempt to match power extractionand wake characteristics at scale, notgeometry
0.2 0.4 0.6 0.8 10.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2x 10
5
r/R Normalized spanwise coordinate
Chord
−bas
ed R
eynold
s num
ber
U=0.5 m/s
U=0.7 m/s
U=0.9 m/s
U=1.1 m/s
Transition?
Solid lines represent DOE RM 1Dotted lines represent lab−scale rotor
DOE RM 1 Turbine Scaling down process!
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WHAT IS TIDAL ENERGY? Background Design Experiment Single Turbine Results Array Results
LABORATORY-SCALE ROTOR GEOMETRY
I Maximize chord-based Reynoldsnumber
I Choose foil to minimize Reynoldsnumber effects
I Match performance and optimum tipspeed ratio with blade-elementmomentum design code
I Attempt to match power extractionand wake characteristics at scale, notgeometry
6 7 8 9 10 110
0.1
0.2
0.3
0.4
0.5
TSR
Eff
icie
ncy
Full−scale DOE RM 1 efficiency(predicted from BEMT)
Lab−scale DOE RM 1 experimental efficiency
Geometrically-scaled DOE RM 1 Turbine Performance!
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6 7 8 9 10 110
0.1
0.2
0.3
0.4
0.5
TSR
Eff
icie
ncy
Full−scale DOE RM 1 efficiency(predicted from BEMT)
Lab−scale DOE RM 1 experimental efficiency
WHAT IS TIDAL ENERGY? Background Design Experiment Single Turbine Results Array Results
LABORATORY-SCALE ROTOR GEOMETRY
I Maximize chord-based Reynoldsnumber
I Choose foil to minimize Reynoldsnumber effects
I Match performance and optimum tipspeed ratio with blade-elementmomentum design code
I Attempt to match power extractionand wake characteristics at scale, notgeometry
Performance-scaled !DOE RM 1 Turbine!
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DOE RM1 @ 45:1 scale Similarity based on performance curves
WHAT IS TIDAL ENERGY? Background Design Experiment Single Turbine Results Array Results
LABORATORY-SCALE TURBINE45 cm diameter rotor
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Experimental CondiAons Rechord ~ 105 Tip Speed Ra4o (TSR) = 4.5-‐8
Blockage Ra4o = 20%
30
Figure 4.1: Photograph of the Bamfield Marine Science Centre flume
4.1.1 Flume dimensions and specifications
The BMSC flume has a width of 2 m, a depth of up to 1 m, and 12.3 m test section
length with full optical access. The pumps that drive the flow are capable of a
volumetric flow rate of approximately 1 m3/s, which results in a freestream flow speed
of 0.5 m/s. This flow speed was judged to be too slow to produce adequate Reynolds
numbers, which are shown to be Re ⇠ 60, 000 at this flow speed in Figure 3.3. To
increase the flow speed, and thus the Reynolds number, a partition was constructed
in the flume, which can be seen in Figure 4.1. This partition halved the flume width
from 2 m to 1 m, doubled the maximum flow speed, and doubled the blockage ratio.
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Three Different Array ConfiguraAons 1. Array of two coaxial turbines.
2. Array of three coaxial turbines.
3. Array of three turbines with lateral offset.
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Measurement LocaAons: Two Turbines Coaxially Mounted
WHAT IS TIDAL ENERGY? Background Design Experiment Single Turbine Results Array Results
TWO CO-AXIAL TURBINES AT VARIOUS SPACINGS
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Performance for Two Coaxial Turbines: Experimental Measurements
WHAT IS TIDAL ENERGY? Background Design Experiment Single Turbine Results Array Results
TWO CO-AXIAL TURBINES PERFORMANCE
5.5 6 6.5 7 7.5 8 8.5 90
0.1
0.2
0.3
0.4
0.5
TSR
Eff
icie
ncy
Performance curves for two co−axially arranged turbinesat various separation distances
Upstream turbine
5D downstream turbine
8D downstream turbine
11D downstream turbine
14D downstream turbine
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Performance of Two Coaxial Turbines: Comparison of Experiments and SimulaAons
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WHAT IS TIDAL ENERGY? Background Design Experiment Single Turbine Results Array Results
TURBINE ARRAYS: THREE CO-AXIAL TURBINES
Measurement LocaAons: Three Turbines Mounted Coaxially
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3-‐Turbine Coaxial Array Performance Comparison of Experiments and SimulaAons
Downstream separaAon 5D
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EvoluAon of the available KineAc Energy Flux a 3-‐Turbine Coaxial Array
Downstream separaAon 5D
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Evolution of TKE contours in a 3-Turbine Coaxial Array!
Downstream separaAon 5D
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3-‐Turbine Offset Array Performance Comparison of Experiments and SimulaAons
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3-‐Turbine Offset Array Performance LES SimulaAons
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InvesAgaAon of the Flume Blockage Effect
ε = 20 % ε = 10 % ε = 5 % *
• Increase in blockage leads into increase in efficiency (verAcal shi[ of Cp curve).
• Increase in blockage shi[s the peak of efficiency toward higher TSR values
(horizontal shi[ of Cp curve).
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Summary and Conclusions!
• Three Turbines Array present non-monotonic performance: third turbine has higher efficiency than middle turbine!
• Confinement plays a increasingly important role for higher number of turbines and lateral offset in the Array.!
• Agreement between experimental and numerical results is best for single turbine and optimum TSR. !
• Angular velocity fluctuations in the experiments, and enhanced wake recovery, not captured by simulations, leads to numerical/experimental divergence with lower TSRs, larger arrays and higher confinement.!
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RMS of Normalized Rota4onal Velocity Temporal Evolu4on (TSR = 6.15, 7.16)
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Array of Three Turbines with Lateral Offset
• ObservaAon of similar physics compared to results from array of two & three coaxial turbines.
• Downstream turbines’ efficiency increase monotonically with the TSR value.
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3-‐Turbine 1/4D Lateral Offset Array Performance
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Reynolds-‐number Dependent Performance
5 6 7 8 9 10 11 120.25
0.3
0.35
0.4
0.45
0.5
TSR
Eff
icie
ncy
Single turbine efficiency at various flow speeds, averaged over one minute
0.52 m/s flowspeed0.61 m/s flowspeed0.65 m/s flowspeed0.71 m/s flowspeed0.75 m/s flowspeed0.90 m/s flowspeed
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Turbine Comparison for Performance
5 6 7 8 9 10 11 12 130
0.1
0.2
0.3
0.4
0.5
TSR
Eff
icie
ncy
Turbine 1Turbine 2Turbine 3
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PIV Velocity Profiles in the Wake turbine
0.4 0.5 0.6 0.7 0.8 0.9 1 1.10
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
Norm
aliz
ed v
erti
cal
dis
tance
fro
m c
ente
rlin
e
Normalized streamwise velocity
Rotor tip
Free surface
Streamwise velocity profiles for TSR 7
2D up
2D down
3D down
5D down
7D down
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Results of BEM study (3/3) Effect of blockage on efficiency
• Blockage increases the efficiency. • Blockage shi[s the peak of efficiency to the right. • Blockage delays the peak of efficiency of the two downstream turbines.
Source : S. J. Miley’s catalog of airfoils
€
α(r)= arctanVinc(r )rω
+ β(r)
Angle of adack :
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3-‐Turbine 1/4D Lateral Offset Array Performance
Downstream separaAon 5D