P.V. Panel wind load effects

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

2

Overview

• Refresh• CFD Progress & Result• Wind-Tunnel Experiment Progress & Result


3

Refresh

• Ideal angle of inclination is 51°

• Too much weight for the roof?

• Wind-Tunnel testing – Experimental

• Computational Fluid Dynamics (CFD) - Computational


4

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


5

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


6

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


7

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)


8

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)


9

CFD – Steady Convergence in CFX


10

CFD - Verification

• Reference: “On the Flow of Air Behind an Inclined Flat Plate of Infinite Span” -Fage and Johansen, 1927.


11

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)


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




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



Distance Along X-Axis (m)

Cp


12

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

[%

]


13


14

CFD – Unsteady Simulations


15

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


Cp


16

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


17

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!


18


19

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


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


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



Err

or

%


20

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


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



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



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


Diff

ere

nce i

n C

oeff

icie

nt

of

Lif

t


21

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%


22

CFD - Recommendations

•Use 3D over 2D▫Other turbulence models only work in 3D

•Use specialized turbulence models▫DES, LES, SAS


23

Experimental Schedule


24

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.


25

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


26

Wind tunnel – Drag Plate

•One load cell (max. 50lbs) installed inside the drag plate

•Two new holes drilled and threaded exactly in the centre


27

Wind tunnel - DAQs

•3 InterfaceTM load cells(25lbs, 50lbs)

•NI 9237(4 Channels)

•NI cDAQ – 9172•NI LabView 2009

with customized vi file


28

Wind tunnel – tunnel systems

•Straight, rectangular wind tunnel

•Two turbines with speed control damper

•Anemometer


29

Wind tunnel – model assembly

• Plastic lamination on the panel• Final Assembly in the wind tunnel• Wooden boards on the sides of the drag plate


30

Wind tunnel – final apparatus

a

Ah

G

l

c

b

d


31

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.


32

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


33

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


34

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


35

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


36

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


37

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.


38

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%


39

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


40

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


41

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.


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Documents

P.V. Panel wind load effects