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Harnessing the Wind: Final Presentation
April 16, 2013
Prepared for Oor, Dean and Airy Products, Winter 2013
Team Dasch-PingliOor, Dean and Airy Products
Saloni DagliMegan DarbyJinhao Ping
Drew Schneir
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
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
Design Summary• Three-Bladed HAWT• Power Output: 0.442 W• Efficiency: 2.43%• Total expenses: $83.57
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
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
Design Evolution
PDR CDR
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
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
Rudder• Attached to lid of gearbox• Made of wooden dowel, 2 thin
plywood sheets• Triangle and square
• Reinforced with smaller wooden sheets
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
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
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
Prototype BudgetItem CostToilet flange $4.43Nylon rope $4.24Bolts/nuts/screws $11.02L-brackets $3.49Hinges $3.29Lazy Susan $2.00Ball bearings $8.80Pulley and belt system $22.22Aluminum sheet $10.48Eye hooks $4.24Extra taxes $9.36Total $83.57
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
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.
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%
Comparison Previous EstimatesVariable 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
Additional Deficiencies and Proposed Solutions
• 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
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
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
Requested Feedback• Benefits of direct connection • Availability of materials in Guatemala• Alternative method to curving our blades • Creating consistent angle of attack
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
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
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
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
