Wind Turbine Prototype

1. Harnessing the Wind:
Final Presentation
April 16, 2013
Prepared for Oor, Dean and Airy Products, Winter 2013
Team Dasch-Pingli
Oor, Dean and Airy Products
Saloni Dagli
Megan Darby
Jinhao Ping
Drew Schneir

2. Overview
• Oor, Dean and Airy Products wants to enter the small-scale
wind turbine market
• Team Dasch-Pingli is tasked with creating a viable prototype
• Goal: to market product to rural communities in Guatemala
• Produce at least 5W in 5m/s wind speeds
• Create electricity to increase productivity
• Improve local standard of living

3. Agenda
• Design Presentation
• Design aspects, building process, materials, budget
• Performance
• Safety inspections, power output and efficiency, design
deficiencies and creative solutions
• Future Plans
• Production problems
• Conclusion
• Feedback, questions

4. Design Summary
• Three-Bladed HAWT
• Power Output: 0.442 W
• Efficiency: 2.43%
• Total expenses: $83.57

5. Design Objectives
• Performance
• Power output
• Efficiency
• Cost Efficiency
• Simple design with sturdy materials
• Most materials are easily found in Guatemala
• Environmental Impact
• Many repurposed materials
• Wooden materials could be composted, metal and plastic could
be recycled
• Safety
• Stable design
• Blunt edges of blades

6. Design Basics
• Three aluminum alloy blades
• Stable square base
• Cinderblocks for stability optional
• Platform Structure
• Square Lazy Susan
• Wooden gear box
• Including stepper motor
• Timing belt/pulley system
• Steel shaft
• Runs through 2 sets of ball bearings, with large pulley attached
• Many materials found and repurposed
• Simple, inexpensive design

7. Design Evolution
PDR CDR

8. Blades
• Three 22 gauge aluminum alloy blades
• Cut with shear saw and notch cutter
• Curved by hand, using PVC pipes for shape
• Hub made with wooden circle
• 6-holed metal toilet flange
• Easy blade placement and balance
• Hub attached to shaft using nuts
• Washers used to level blades with hub
• Duct tape added for safety

9. Gearbox
• 8”x8”x4” Plywood box, L-bracket connections
• Hinged top for easy access
• Bearings at front and back of box with shaft running through
• Screw through shaft in front of first bearing to prevent sliding
• Timing belt and pulleys, 2:1 gear ratio
• Attached to Lazy Susan for yawing motion

10. Rudder
• Attached to lid of gearbox
• Made of wooden dowel, 2 thin
plywood sheets
• Triangle and square
• Reinforced with smaller wooden
sheets

11. Base
• 2’x2’ wooden square and 1’x1’
platform with Lazy Susan
• Floor flange and threaded
steel pipe
• Ropes and eye hooks
connecting top and bottom
platforms
• 2”x4”s used to elevate bottom
platform, protect SRB roof
• Cinderblocks needed for
stability

12. Electrical Configuration
• Wires running from gear box through tower pipe to ground
• Two phases connected in series, Rg = 16 Ω
• Load resistance: Three 50 Ω resistors attached in parallel,
approximately 16.7 Ω
• Maximum power output when load resistance and generator
resistance are equal

13. Interesting Features
• Toilet flange used on
center hub
• Wooden block and bolt
used to connect tower
with platform
• Nylon ropes for added
support
• Detachable base
• Detachable hub

14. Prototype Budget
Item Cost
Toilet flange $4.43
Nylon rope $4.24
Bolts/nuts/screws $11.02
L-brackets $3.49
Hinges $3.29
Lazy Susan $2.00
Ball bearings $8.80
Pulley and belt system $22.22
Aluminum sheet $10.48
Eye hooks $4.24
Extra taxes $9.36
Total $83.57

15. Design Simplicity
• All wood, many metal materials repurposed
• 2”x4”s, wooden plywood, metal flange hub and metal tower
• Connections and design minimalistic/economical
• Toilet flange with 6 pre-drilled holes provided blade balance
• Base was simple yet sturdy
• No advanced craftsmanship necessary

16. Resolved Design Deficiencies
• Shaft slid through bearings due to drag force of wind on hub
• Pin inserted through shaft, in front of first bearing
• Toilet flange was raised above wooden hub
• Washers added for blade-hub connection
• Rudder placed for easy access to gearbox, reinforced to
prevent breakage.

17. Performance
• Completed on time, by 4/13
• Passed safety inspections
• Lit the light: “The harder to get,
the better to have”
• Maximum power output: 0.442 W,
in 3.6 m/s wind speeds
• Tip speed ratio: 3.6
• Efficiency: 2.43%

18. Comparison Previous Estimates
Variable CDR Assumption Prototype Data
Resistance 120 Ω 16.7 Ω
Wind speed 2.36384 m/s 3.6 m/s
Gear ratio 3.1 : 1 2 : 1
Tip speed ratio 3 to 5 3.6
Efficiency At least 10% 2.43%
Power output 5.2 W 0.442 W
• Actual power output was much lower than predicted
• Inefficient connection using timing belt and pulleys
• Friction in bearings, other moving parts
• Unable to collect power in higher wind speeds due to design
deficiencies

19. AdditionalDeficienciesand ProposedSolutions
• Blades were too flexible, bent easily
• Use thicker aluminum sheets for production
• Bearings were difficult to attach to wood
• Flanged bearings
• Inconsistent angle of attack on blades
• Alternative method to hand-shaping
• Nuts connecting hub to shaft unscrewed in high wind speeds
• Self locking nuts
• Many connections relied on Gorilla Glue, hot glue
• Nuts and bolts for connections rather than glue
• Small pulley connection
• Smaller bore size to fit generator shaft

20. Next Steps
• Proceeding with plans for scaling-up and improved
performance
• Detailed in a report by April 23rd
• Aim to enter large-scale production in coming months

21. Conclusion
• Purpose: to help spread
reliable electricity to
Guatemala
• A three-bladed HAWT
design is an effective and
reliable way to achieve
this
• Power Output: 0.442 W
• Efficiency: 2.43%
• Expense: $83.57

22. Requested Feedback
• Benefits of direct connection
• Availability of materials in Guatemala
• Alternative method to curving our blades
• Creating consistent angle of attack

23. Contact
daschpingli@umich.edu

24. Power and Efficiency Calculations
• Wind speed: 3.6 m/s
• Vload = 2.74 V
• Powerload = V2/R = 0.442 W
• Power in wind = .5*ρ*A*u3 = 18.19 W
• Efficiency = Pload/Pwind = 2.43%
• felectric = 462.3 Hz
• ωg = felectric * (2π/50)
• ωt = ωg/2
• Tip speed ratio X = ωtR/u = 3.63

25. Scale Up
• To achieve 5W in 5 m/s wind speeds, given same end to end
efficiency:
• New swept area: 2.74 m2
• New blade length: 0.93 m
• New gear ratio: 4.2:1
• Larger base to support larger blades
• 4’x4’
• Taller tower for safety, access to higher wind speeds
• 2 m

26. Production Plans
• Look to recycle old materials, in order to cut back on costs and
environmental impact
• Repurposed wood, metal pipes
• Wood and possible metal would be easy to find in Guatemala
• Small parts less expensive in bulk (pulleys, bearings, etc.)
• Design Changes
• Thicker aluminum blades
• Consistent angle of attack for all blades, increase tip speed ratio
• Steel wires running from top platform, staked in ground
• Less reliance on Gorilla Glue

27. Safety Inspections
• Blowdown test
• Stable base
• High winds test
• Drunk pedestrian
• Technical requirements
• Appropriate dimensions
• All dangerous edges or parts blunted
• Rooftop integrity
• Used foam to cover sharp parts
• Raised off roof for protection