P.V. Panel wind load effects

1. TEAM 12 P.V. Panel wind load effects Winter Project Review April 2011 Arman Hemmati , Brady Zaiser, Chaneel Park, Jeff Symons, Katie Olver

2. Overview • Refresh • CFD Progress & Result • Wind-TunnelExperiment 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 • 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 • 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 – Expectations • Establish a functional and feasible model • 2-Dimensional • C.V. size (inlet and outlet buffer zones) • Turbulence Model – k-epsilon, RNG k-epsilon • Confirm the credibility of the model • Pressure Coefficient (CP) – Front and Rear Surfaces • CL and CD • Convergence • Parameter variation study • Panel angle of attack • Panel – Rooftop separation distance • Wind speed / Reynolds Number • Number of panel in series Interconnected

7. CFD – Validation • Geometry – Horizontal Open Channel • Simple Physics – Laminar flow • Open Channel Flow: Wall (No Slip) Inlet Height (m) Outlet Wall (No Slip) Velocity (m/s)

8. CFD – Validation • Pressure Coefficient • Vertical Flat Plate

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.

12. CFD – Initial Results

14. CFD – Unsteady Simulations

15. CFD – Unsteady Simulations

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!

19. CFD – Drag Results

20. CFD – Lift Results

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

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 l a d h A b G c

31. Wind tunnel – testing parameters 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

33. Experimental Result - Drag

34. Experimental Result - Lift

35. Experimental Result - Lift

36. Comparison to Theoretical Values

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

39. Load Cell Credibility

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.

42. www.ucalgary.ca/deloprec