p.v. panel wind load effects a pril 2011 arman hemmati, brady zaiser, chaneel park, jeff symons,...
TRANSCRIPT
P.V. PANEL WIND LOAD EFFECTS
APRIL 2011
Arman Hemmati , Brady Zaiser, Chaneel Park, Jeff Symons, Katie Olver
Winter Project Review
TEAM 12
April - 2011Design Review #5: DeLoPREC
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Overview
• Refresh• CFD Progress & Result• Wind-Tunnel Experiment Progress & Result
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Refresh
• Ideal angle of inclination is 51°
• Too much weight for the roof?
• Wind-Tunnel testing – Experimental
• Computational Fluid Dynamics (CFD) - Computational
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CFD – Software Packages• ANSYS CFX
▫ Employing Finite Element Method (FEM)▫ Best in Single Physics Modeling ▫ Mostly used for modeling of Solids▫ University of Calgary Licensing
• Comsol Multiphysics▫ Works on basis of FEM▫ Multi-physical modeling▫ Best suited for modeling of Fluids, Stationary Solids▫ Shell Canada Licensing
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Computational – 2D vs. 3D Modeling
1. Two-Dimensional (2D) Models▫ Easier to develop, evaluate, and understand▫ Typically the start of an analysis▫ Provides a general overview to the forces expected in the
wind tunnel
2. Three-Dimensional (3D) Models▫ More Difficult to set-up, and develop▫ More powerful computers required▫ More realistic model of the actual phenomena▫ Typically used to compare to the wind tunnel testing
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CFD – Expectations1. Establish a functional and feasible model
a) 2-Dimensionalb) C.V. size (inlet and outlet buffer zones)c) Turbulence Model – k-epsilon, RNG k-epsilon
2. Confirm the credibility of the model
a) Pressure Coefficient (CP) – Front and Rear Surfaces
b) CL and CD
c) Convergence
3. Parameter variation study
a) Panel angle of attackb) Panel – Rooftop separation distancec) Wind speed / Reynolds Number d) Number of panel in series
Interconnected
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CFD – Validation
• Open Channel Flow:Geometry – Horizontal Open
ChannelSimple Physics – Laminar flow
Wall (No Slip)
Wall (No Slip)
Ou
tlet
Inle
t
Velocity (m/s)
Heig
ht
(m)
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CFD – Validation• Pressure Coefficient
• Vertical Flat Plate
11.5 12 12.5 13 13.5
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
Pressure Coefficient Along Front and Back Surfaces of a Vertical Flat
Plate (2D)
FrontBack
Distance Along Y-Axis (m)
Pre
ssure
(P
a)
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CFD – Steady Convergence in CFX
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CFD - Verification
• Reference: “On the Flow of Air Behind an Inclined Flat Plate of Infinite Span” -Fage and Johansen, 1927.
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11.5 12 12.5 13 13.5
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
Pressure Coefficient Along Front and Back Surfaces of an Inclined
(90deg) Flat Plate (2D)
Distance Along Y-Axis (m)C
p
10.9 11.1 11.3 11.5 11.7 11.9 12.1 12.3 12.5 12.7
-1
-0.5
0
0.5
1
Pressure Coefficient Along Front and Back Surfaces of an
Inclined (70deg) Flat Plate (2D)
Distance Along Y-Axis (m)
Cp
10.9 11.1 11.3 11.5 11.7 11.9 12.1 12.3
-1.1
-0.6
-0.1
0.4
0.9
Pressure Coefficient Along Front and Back Surfaces of an
Inclined (51deg) Flat Plate (2D)
Distance Along Y-Axis (m)
Cp
-0.1 0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5
-1.3
-0.8
-0.3
0.2
0.7
Pressure Coefficient Along Front and Back Surfaces of an
Inclined (30deg) Flat Plate (2D)
Distance Along X-Axis (m)
Cp
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CFD – Initial Results
20 30 40 50 60 70 80 90 1000%
25%
50%
75%
100%
f(x) = − 0.000430477231319 x + 0.266165919788991
Coefficient of Drag Error (Exp. v.s. Comp.)
[ ]a degreesCD
-ER
RO
R [
%]
20 30 40 50 60 70 80 90 1000%
25%
50%
75%
100%
f(x) = 1.65071261751711E-05 x + 0.251118597093691
Lift Coefficient Error (Exp. v.s. Comp.)
[ ]a degreesCL-E
RR
OR
[%
]
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CFD – Unsteady Simulations
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CFD – Unsteady Simulations
11.5 12 12.5 13 13.5
-2
-1.5
-1
-0.5
0
0.5
1
Pressure Coefficient Along Front and Back Sur-faces of an Inclined (90deg) Flat Plate (2D)
FrontBack
Distance Along Y-Axis (m)
Cp
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CFD – Now What?
• Can not get rear of panel to match research
• Panel Angle: 10°, 30°, 51°, 70°, 90°
• Flow Type: Steady, Unsteady
• Turbulence Model: k-ε , RNG k-ε
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CFD – Unsteady Data Collection
• Time steps set to 0.01s• Pressure data recorded every 5 time steps• Averaged over 10s• 10s/0.05s = 200 pressure plots• X 10 unsteady simulations = 2000 pressure plots to
export from CFX into Excel!
• The solution: Macros!
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CFD – Drag Results
0 10 20 30 40 50 60 70 80 90 1000.00000
0.50000
1.00000
1.50000
2.00000
2.50000
Flat Plate Drag Coefficient at Different Angles of Attack
Steady k eSteady RNG k eUnsteady k eUnsteady RNG k eTheory1927 ExperimentCOMSOL Steady k-eWind Tunnel
Angle of Attack (degrees)
Coeff
icie
nt
of
Dra
g
20 30 40 50 60 70 80 90 1000
10
20
30
40
50
60
70
% Error of Drag Coefficient with 1927 Experiment
Steady k eSteady RNG k eUnsteady k eUnsteady RNG k eComsol Steady k-eWind Tunnel
Angle of Attack (degrees)
Err
or
%
20 30 40 50 60 70 80 90 1000
0.2
0.4
0.6
0.8
1
1.2
Difference of Drag Coefficient from the 1927 Experiment
Steady k eSteady RNG k eUnsteady k eUnsteady RNG k eCOMSOL Steady k-eWind Tunnel
Angle of Attack (degrees)
Diff
ere
nce i
n C
oeff
icie
nt
of
Dra
g
20 30 40 50 60 70 80 90 1000
10
20
30
40
50
60
70
80
90
% Error of Drag Coefficient with Flat Plate Emprical Solution
Steady k eSteady RNG k eUnsteady k eUnsteady RNG k eComsol Steady k-eWind Tunnel
Angle of Attack (degrees)
Err
or
%
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CFD – Lift Results
0 10 20 30 40 50 60 70 80 90 100
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
Flat Plate Lift Coefficient at Different Angles of Attack
Steady k eSteady RNG k eUnsteady k eUnsteady RNG k eTheory1927 ExperimentCOMSOL Steady k-eWind Tunnel
Angle of Attack (degrees)
Coeff
icie
nt
of
Lif
t
20 30 40 50 60 70 80 90 1000
50
100
150
200
250
300
350
400
% Error of Lift Coefficient with Flat Plate Empir-ical Solution
Steady k eSteady RNG k eUnsteady k eUnsteady RNG k eComsol Steady k-eWind Tunnel
Angle of Attack (degrees)
Err
or
%
20 30 40 50 60 70 80 90 1000
20
40
60
80
100
120
140
160
180
200
% Error of Lift Coefficient with 1927 Experiment
Steady k eSteady RNG k eUnsteady k eUnsteady RNG k eComsol Steady k-eWind Tunnel
Angle of Attack (degrees)
Err
or
%
20 30 40 50 60 70 80 90 1000
0.2
0.4
0.6
0.8
1
1.2
1.4
Difference of Lift Coefficient from the 1927 Exper-iment
Steady k eSteady RNG k eUnsteady k eUnsteady RNG k eCOMSOL Steady k-eWind Tunnel
Angle of Attack (degrees)
Diff
ere
nce i
n C
oeff
icie
nt
of
Lif
t
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CFD - Strouhal Number
• Relationship for vortex shedding frequency
• Flat Plate, St = 0.16 f= 2.8 Hz
• CFX gives St = 0.22 f= 3.94 Hz
• Error = 41%
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CFD - Recommendations
•Use 3D over 2D▫Other turbulence models only work in 3D
•Use specialized turbulence models▫DES, LES, SAS
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Experimental Schedule
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Wind Tunnel – Schedule Delay
• Manufacturing order to the faculty machine shop submitted February 4
• Drag Plate and DAQs system faults found during preliminary tests. (Hardware line-up problem and software problem). Adjustment in process.
• Products finished by Mar. 11th, but software could not be improved. Has to take 3 different measurement assuming wind velocity is constant.
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Wind Tunnel – Budget
•Drag plate, wind tunnel, DAQs system borrowed for free from the department
Panel Model
Drag Plate Wind Tunnel
DAQs
Material: $10.00 $0.00 $12.87 $0.00
Labour: $25.00 $0.00 $0.00 $0.00
Total: $35.00 $0.00 $12.87 $0.00
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Wind tunnel – Drag Plate
•One load cell (max. 50lbs) installed inside the drag plate
•Two new holes drilled and threaded exactly in the centre
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Wind tunnel - DAQs
•3 InterfaceTM load cells(25lbs, 50lbs)
•NI 9237(4 Channels)
•NI cDAQ – 9172•NI LabView 2009
with customized vi file
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Wind tunnel – tunnel systems
•Straight, rectangular wind tunnel
•Two turbines with speed control damper
•Anemometer
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Wind tunnel – model assembly
• Plastic lamination on the panel• Final Assembly in the wind tunnel• Wooden boards on the sides of the drag plate
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Wind tunnel – final apparatus
a
Ah
G
l
c
b
d
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Wind tunnel – testing parameters
Tests Number
Wind Direction Front, Back 2
Panel Angle 35°, 51°, 65°, 79° 4
Panel Gap 0 ~ 15cm 14
Total 112
In the result, we had total of 144 runs including repetition & make-ups for mistakes. For each run we had to take 3 different measurement, resulting in total of 432 data files to analyze.
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Experimental Result – Drag
0 2 4 6 8 10 12 14 160.300
0.400
0.500
0.600
0.700
0.800
0.900
1.000
1.100
1.200
Drag(Wind blowing from the front)
51 degrees65 degrees35 degrees79 degrees51 degrees(BB)
Gap from Floor(cm)
Dra
g C
oeff
icent
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Experimental Result - Drag
0 2 4 6 8 10 12 14 16 180.200
0.300
0.400
0.500
0.600
0.700
0.800
0.900
1.000
1.100
Drag(Wind blowing from the back)
51 Degrees65 degrees35 degrees79 degrees51 degrees(BB)
Gap from the floor(cm)
Dra
g C
oeff
cie
nt
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Experimental Result - Lift
0 2 4 6 8 10 12 14 16
-1.200
-0.700
-0.200
0.300
0.800
Lift(Wind blowing from the front)
51 degrees65 degrees35 degrees79 degrees51 degrees(BB)
Gap from floor (cm)
Lif
t C
oeff
icent
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Experimental Result - Lift
0 2 4 6 8 10 12 14 16 18
-1.000
-0.800
-0.600
-0.400
-0.200
0.000
0.200
Lift(Wind blowing from the back)
51 Degrees65 degrees35 degrees79 degrees51 degrees(BB)
Gap from the floor(cm)
Lif
t C
oeff
icie
nt
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Comparison to Theoretical Values
30 40 50 60 70 80 90
-1.000
-0.500
0.000
0.500
1.000
1.500
2.000
2.500
Drag and Lift Coefficients Over Varying Angles
Drag CoefficientLift CoefficientsTheoretical DragTheoretical LiftDrag/Lift Ratio Check
PV Panel Angle
Dra
g a
nd L
ift
Coeff
icie
nts
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Experimental Verification
•Load cell credibility -> Fish scale Verification
•Effect of built up pressure on drag plate -> Fish scale with weight
•Lift and Drag Relationship: , especially at higher
angle.
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Effect of Pressure on Measurement
Exp Fish Scale(kg) Load Cell(lbs) Fish Scale(N) Load Cell(N) % Error
Drag 1 0 0.5738727.468 29.889 8.82%
Drag 2 2.8 7.293254
Drag 3(with weight) 0 0.44018930.411 29.209 3.95%
Drag 4(with weight) 3.1 7.006685
Drag 5(with weight) 0 0.37218627.959 26.470 5.32%
Drag 6(with weight) 2.85 6.322863
Load Cell(lbs)(Without weight) Load Cell(lbs)(With Weight) % Error
Load cell 1 161.8012 161.6372 0.10%
Load Cell 2 11.22869 11.43814 1.87%
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Load Cell CredibilityFish Scale(N) Load Cell(N) Sum % Error
Load Cell 1
-49. 05
-4.905944
-47.13 3.92%
Load Cell 2 -42.220699
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Real PV Panel – Worst Case Scenario
•Wind Blowing from the Front▫Max CoD: 0.816 -> 674.28N @ 29m/s▫Max CoL: 0.549 -> 453.65N @ 29m/s
•Wind Blowing from the Back▫Max CoD: 0.535 -> 442.08N @ 29m/s▫Max CoL: 0.573 -> 473. 48N @ 29m/s
•Required Mass of Concrete Blocks: 196.66kg -> 3 Blocks (240kg) / Panels
•Maximum Load applied to Roof: 2.81kN/Panels
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Conclusion
•Measurements from our DAQs is reliable•However, there are results we cannot
understand fully. Sources of error could be: Velocity profile and wall effects.
April - 2011Design Review #5: DeLoPREC
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