Anthony Benasco, Hulon Reid, and Brody Holloway
Senior Design Final Proposal
Advisors: Dr. Cris Koutsougeras and Dr. Junkun Ma
Spring 2014
Abstract:
Wind turbines, along with other clean alternative energy methods, have been utilizing the
planet’s natural resources to extract energy in a form that is usable and meets our daily
necessities. In terms of creating this energy, a wind turbine converts the kinetic energy from the
wind into mechanical energy from the rotating blades; furthermore, it then converts into
electrical energy. However, there are numerous unique turbines with regards to its design
schematic, efficiency, size, and many more. Commonly, these turbines consist of a horizontal
shaft, yet recent experiments found that a vertical setup can provide even more efficiency by
producing a greater output.
Introduction/Purpose:
Over the past centuries, technological advancement has been undergoing an enormous
transformation with new research discoveries and innovative inventions. With this in mind, we
are always looking for new methods of improving our lifestyles and the world we live in with
these new technologies and machineries. This project’s purpose is to seek a new prototype
design that not only has a distinctive design but promotes an alternative technique to achieve the
most efficiency possible.
The concept behind the prototype wind turbine is very straightforward. The blades are
simply flat panels made of light, heavy duty material, such as carbon fiber, stainless steel, or
aluminum. The orientation of these panels will change with respect to the wind direction. One
blade will be in the vertical position for two quadrants, while the opposite panel will be
positioned horizontally for the other two. These design schematic allows two panels to coincide
with one another in order to produce higher efficiency with more rotations per minute (rpm).
The mechanical aspect of this machine will be one of the more challenging obstacles in the
component design and construction phase, which is discussed more in detail below. It is very
vital for the system to be capable of adjusting to the variations in wind direction and speed
because if it cannot achieve this, it defeats the purpose of the installed system components and
the mechanisms behind the design.
Initial Design Phase:
Currently, the wind turbine system is in the design phase with researching the necessary
components and physical forces that could affect and potentially cause the system to fail. Since
the blades have to be adaptive to the wind deviation in magnitude and direction, the components
being examined are both the CAM System and weather vane. This weather vane must be
installed at the peak of the structure to notify the system in these changes in the wind. The CAM
System is a mechanical instrument that will initiate the flipping action of each blade of the wind
turbine. The CAM System design is essential for the turbines success. Without a proper design,
the panels will flip into an improper arrangement that will slow down the rpm; thus, less output
can be attained. Since the CAM design will be fixated—never changes—there needs to be a
corresponding device that will rotate this CAM into the proper orientation. This can be
accomplished with a gear that is electrically motorized to rotate the CAM when the wind
direction changes. Since the system needs to be continuously updated with the current wind
direction, there is a weather vane that will be installed at the top of the shaft. The rotation of the
weather vane will notify the system that adjustments with the CAM’s orientation need to be
made. This is accomplished by a very small device known as a micro switch. Two micro
switches will be placed 180 degrees apart from one another. They will send electronic signals to
the electric motor whose responsibility is solely rotating the gear. Moreover, it will allow the
CAM to be orientated in the appropriate manner. As shown above, after given a specified wind
direction, there is only one airfoil panel that will be completely vertical to capture most of the
winds force, building a pressurized cross-sectional area on one side of the shaft. This, in return,
creates a rotational force that will provide us utilizable energy through the conversion of kinetic
(mechanical) energy to electrical energy. The electrical energy is generated by the alternator,
which is located at the base of the shaft with most of the complex components in the system.
There is a pulley system that connects directly to the shaft pulley, allowing energy to be created
through mechanical work.
The system can be better understood by getting a bird’s eye view of the system’s airfoil,
and how each coincides with one another to create a less resisting system, which creates a unison
circular movement around the axis of rotation. There are four panels overall, each installed
directly to the shaft at 90 degrees apart. One panel is perfectly vertical for a 90 degrees interval.
This portion of the quadrants will provide the system the most rotational force, so it must remain
in this fixated position. The panel will begin its flipping motion once it begins to approach the
first quadrant (shown in the diagram). The CAM plate will begin to slope downward to allow
this mechanical flipping motion to take place. The flipping motion will either commence or
cease at the end of the CAM’s ramp (between quadrants II/III and IV/I). The panels will remain
perfectly in the horizontal position until it reaches the end of quadrant II. This CAM design was
determined theoretically the most efficient, but further experimental evaluation will confirm
what framework will be the constructed for the wind turbine.
COMSOL:
To gain a more practical understanding with regards to the wind turbines efficiency and
stress/strain load, an additional software program was utilized to perform theoretical
calculations, known as COMSOL. It provides visual and mathematical analysis that is vital to
our system. The first portion of the calculation was used to measure the amount of pressure
(Pascal’s) in a given cross-sectional area. The diagram below is a simple representation of an
airfoil perpendicular to the wind direction, providing the maximum pressure. However, the goal
behind the usage of COMSOL is to compare theoretical values as one variable is adjusted in each
scenario. This information gives an insight of how large these airfoils must be in order to
achieve optimal output readings.
This project will continue onto the next semester with much more emphasis on the
practical construction of the wind turbine. There are a series of calculations that need to be
complete within the allotted time given, such as theoretical work, proper sizing of airfoils, more
detailed shaft structure, and the best CAM system design. The theoretical work must be
calculated via COMSOL to produce the results needed. It will remain as one of the most
challenging aspects to the design phrase. There could be potential changes to the design of the
wind turbine structure if there is a need for improvement. The CAM system will be tested
experimentally by producing a series of unique design. Each system will be influenced by the
same magnitude of wind velocity, and the design that promotes the highest rpm values will, in all
likeliness, be used in the construction phase. There are a few calculations in the following
section that remain to be computed, but will be solved in manner of proper time.
Calculations:
Chain Design:No. 80 Chain, 1 inch pitchLength = 100 pitches, 100 inch ChainCenter Distance = 30.26 inch (Maximum)Sprockets = Large, 59 teeth, D = 18.789Small, 17 teeth, D = 5.442Input RPM @ 3 MPH = 38 RPM (Estimated)Output RPM = 130 Minimum, 2500 MaximumRatio = 130 RPM / 38 RPM = 3.421Sprocket for DC-540 Motor (N1) = 17 teethSprocket for Wind Turbine Shaft (N2) = N1 * RatioN2 = 17 * 3.421 = 58.2 since an even number of teeth is not recommended, we chose a sprocket with 59 teeth.Actual expected output speed = 38(59/17) = 131.9 RPMPitch Diameters of the sprockets. We chose a 1 inch pitch chain. (p = 1)D1 = p / sin(180/N1) = 1 in / sin(180/17) = 5.442 inchD2 = p / sin(180/N2) = 1 in / sin(180/59) = 18.789 inchNominal center distance = 30 pitchesRequired chain length (L) = 2C + [(N2+N1)/2] + [(N2-N1)^2 / (4*PI^2 *C)L = 2(30) + [(59+17)/2] + [(59-17)^2 / (4*PI^2*30)] = 99.49 pitchesChain Length = 100 pitch, 100 inchCenter Distance © = .25[L – (N2+N1)/2 + Sqrt[(L – (N2+N1)/2)^2 – 8(N2 –N1)^2/(4*PI^2)]C = .25[100 – (59+17)/2 + Sqrt[(100 – (59+17)/2)^2 – 8(59 –17)^2/(4*PI^2)] = 30.262 Pitches
C = 30.262(1 in) = 30.262 inch (Maximum)The Angle of wrap (@) for the chain on each sprocket.@1 = 180 – 2 sin^-1 [(18.789-5.442) / 2(30.262) = 154.52 degrees@2 = 180 + 2 sin^-1 [(18.789-5.442) / 2(30.262) = 205.48 degrees
Shaft Design:We will use a Car Axle for the shaft that is attached to the Wind Turbine and drivingsprocket.Length = 92 in, Width = 4 inProperties of ShaftTensile Strength = 55 KSI, Yield Strength = 30 KSI, Ductility = 25%Size Factor (Cs) = .75Reliability Factor (Cr) = .75 (99.9% Reliability)Endurance Strength (Sn) = 20 KSIActual Endurance Strength (Sn’) = SnCsCr = 20*.75*.75 = 11250 PSIDesign Factor = 2@ 3 MPH the Torque = 63000(.0065 HP) / 38 RPM = 10.8 lb-in@ 10 MPH the Torque = 63000(.0754 HP) / 126 RPM = 37.7 lb-in@ 20 MPH the Torque = 63000(.5104 HP) / 252 RPM = 127 lb-inForce on ShaftForce = T / D = 127 / 12 = 10.58 lbEFy = 0EFx = 0 = Fxb - Fxa = Fxa = 10.58 lb and Fxb = -10.58 lbMax Stress = Stress Concentration Factor (Kt)*[4*Vertical Shear Force (V) / 3* Area of cross section (A)] = 2*[(4*10.58) / (3*1.571)] = 17.96 PSIA = (PI*D^2 / 4) = (PI*2^2 / 4) = 1.571 in^2V = Sqrt[Resultant Y^2 + Resultant X^2] = Sqrt[0^2 + 10.58^2] = 10.58 lbKt = 2N = .577(Sn') / Max Stress = .577(11250) / 17.96 = 361.43Required shaft Diameter (D) = Sqrt[2.94 (Kt*V*N) / Sn’]D = Sqrt[2.94(2*10.58*361.43) / 11250 = 1.414 inchTip Speed Ratio (TSR)TSR = Tip Speed of Blade / Wind SpeedTip Speed of Blade = (2 * PI*r) / TimeMax Power = (4* PI) / n
Optimal TSR = 6 for a two blade Wind Turbine6 = Tip Speed of Blade / Wind Speed@ 3 MPH or 1.34 m/sTip Speed of Blade = 6 * 1.34 m/s = 8 m/s Tip Speed of Blade = (RPM * PI * D) / 60Diameter (D) = 4m RPM = (Tip Speed of Blade * 60) / (4 * PI)RPM = (8 m/s) * 60) / 4 * PI = 38 RPM
Reacting Forces for Components on Platform
The platform will be 3 feet with a two feet overhang for the gears, chain, and motor. There will be a concentrated load of 270 pounds on the center of the three feet. There will also be a force of 30 pounds on the overhang of the two feet (gears, chain, and motor).
Forces in the x-direction equals zero: F(x) = 0
Forces in the y-direction: F(y) = 0 = - R1 – R2 + 270lbs + 30 lbs
Moment of Bending is calculated by:
0 = (270lbs)(1.5ft.) + (30lbs)(5ft) – R2(3ft)
= (405 lbs-ft) + (150 lbs-ft) – R2(3ft)
= (555 lbs-ft) – R2(3ft)
R2 = 555 lbs-ft / 3ft = R2 = 185 lbs Reaction force on the end of plate before overhang
F(y) = 0 = - R1 – (185 lbs) + (270lbs) + (30lbs)
Solve for R1 R1 = 115 lbs Reaction force at the far left end of plate
Approximate Weights for Vertical Wind TurbineComponent Weight (lbs)
Vehicle Axle (Shaft) 100DC -540 Low Wind Permanent Magnet
Alternator11
Sprockets and Chain 15Louvers 100
CAM System 25Bearings 4
Relay Box 3Approximate Total Weight 258 lbs
BudgetProduct Dealer Cost
DC – 540 Low Wind Permanent Magnet Alternator
Wind Blue $199.00
1000 Watt Wind Turbine Generator Grid Inverter
EBay $259.00
59 teeth Driver Sprocket No. 80 1 inch pitch
WBC Industry $240.78
17 teeth Driver Sprocket No. 80 1 inch pitch
WBC Industry $25.58
Miscellaneous (bearings, electronics, circuit, etc..)
N/A $800.00
Approximate Cost : $1524.36
Technical Specifications for a DC- 540 Low Wind Permanent Magnet Alternator
This PMA unit features a completely brushless design that eliminates the need for
maintenance and reduces friction, specially wound Low RPM Output stator. Super Strong N50
grade Neodymium rare earth magnets are at its core to replace the inefficient electromagnetic
field coil. Zero Cogging It is built using Brand New GM Delco alternator components including
NEW Stator Coils, factory balanced Stainless Steel shafts and New Rotor Pole Shoes.
Replacement bearings and parts will be available for years. Built-in rectifier. (DC output is
unregulated) This unit is perfect for direct drive wind turbines in areas that only see 5-15 MPH
winds on average. Not recommended for motor driven or geared up wind use. Please select our
DC-512 model for use with engine driven applications and DC-520 for geared up wind use. Built
to last with new bearings and a baked on clear ceramic finish that will last for years in harsh
outdoor environments. A 90 day full replacement warranty on all units (warranty void if PMA
has been opened or tampered with) produces 12 Volts at just 130 RPM and the voltage keeps
going up from there (see chart below). It makes over 350 volts at 2500 RPM. Also, it produces
up to 15 amps into a 12 volt battery at 2000 RPM.
Dimensions of the DC – 540 Low Wind Alternator
Turbine Construction:
In order to promote the most efficient turbine, the structure needs to have a light weight
airfoil design with a superior base support foundation that will withstand substantial hurricane
force winds. The base portion of the structure is currently in the planning phase. This job is
being conducted by a small group of construction engineers. To begin the design, some factors
that need to be acknowledged include the overall weight of the turbine, composition materials,
potential sizing (airfoil and shaft length), and many others. The height of the turbine needs to be
overshadowing any nearby complexes and trees. The approximation on the height is roughly
between 40-60 feet. The width of the airfoils is also an essential factor to consider. Basic
knowledge of fundamental physics principles, the amount of torque that can be created by
contact with the airfoil increases as the wingspan extending from the axis of rotation increases.
It will take less wind force to cause the turbine to rotate and create utilizable energy. However,
with this in mind, the weight of the turbine will also increase, making it more difficult for
rotation to occur. There is a certain wingspan that will give the turbine the most efficiency. The
initial design wingspan was to construct the airfoils at around 16-20feet from one airfoil to
another. Although durability is a huge aspect towards the airfoil construction, a light weight
material composition needs to be included. A variety of materials were considered for the
design, such as sheets of aluminum, carbon fiber, steel, and so on. After a wide range of
searching and measuring the pros and cons, the airfoil was decided to be made of corrugated
plastic. This material composition meets the necessary requirements to prepare the airfoil
devices. On several websites, these plastics have a single dimension that reached 8 feet by 4 feet
which is very close to our original intentions. Along with durability, the corrugated plastics have
a much lighter composition compared to aluminum and steel. Carbon fiber may have a good
advantage to the corrugated plastics, but cost becomes another issue in this decision process.
With this project ranging from several hundred to thousands, the cost of carbon fiber is relatively
expensive. Corrugated plastics can range from $20-60 with no adjustments needed for the
sizing.
This vertical wind turbine consists of four different panels on the same plane. The
dimensions of the frame were designed by the max amount of wing span I could achieve with the
amount of material given. Aluminum tubing (1 inch by 1 inch) was chosen to be the material
used for the frames because of its lightweight and durability. The dimensions of the frame is 44
in. by 95.5 in (inside to inside) and 46 in. by 97.5 (outside to outside) to be exact. A piece of
aluminum tubing is placed in the center of the frame to reduce twisting, stabilize the frame, and
to be a stopping point for the air foils. After the dimensions were cut, I took all the frames to a
welding shop to be fabricated. The dimensions of the frame depended on the size of the air foils
and how many were going to be used. The frames would then be attached to the shaft.
We chose to use corrugated plastic (.5 in. thick) for the air foils. The air foils
constructed out of Corrugated Plastic Sheets will open and close by wind pressure, and it will
swivel on a rod attached to the frame. Four pieces of corrugated plastic (12in. by 95 in.) are
used in each frame to act as a louver system. At the center of each corrugated plastic piece, a cut
out was made (1 ¼ in. wide and 6 in high) because of the aluminum tubing that was placed in the
center to stabilize the frame and so each piece would overlap properly. Each piece of corrugated
overlaps each other by 1 in. The connectivity of the airfoils becomes rather simple since we
chose to use the corrugated plastic design. The unique characteristic of the plastic is due to the
square concavities on the interior of the sheet. This allows easy installation of the airfoil arms
that extends from the shaft to the outer aluminum support frame. The airfoil arms are being
made out of aluminum rods that will slide into these concavities and attach directly to the frame
support. Simplicity is vital to making the turbine successful since there are many mechanical
parts involved with the turbine functionality. An aluminum rod (5/16 in.) is used to connect the
corrugated plastic to the aluminum tubing. Each rod was cut 98.5 in. and was inserted through
the corrugated plastic and through the aluminum tubing. On one end of the tubing, the aluminum
rods comes out 1 inch passed the tubing. A hole was drilled through the rod, so a pin could be
placed in order for the rod not to back out. Spray foam will be applied inside the tubing, so
grease fittings can be installed on each end of the rod so the four different corrugated plastic
sheets can swivel. The spray foam will ensure that the grease will stay in the one spot applied
and not run down the tubing. This will allow the rods to be greased and create less friction.
Weights
4 Corrugated Plastic Sheets 15 lbs.
Aluminum Tubing 15 lbs.
Total Weight of One Panel = 30 lbs * 4 panels = 120 lbs. Up Top
Each panel covers 31.15 square feet.
All of the panels are fabricated with the air foils installed inside. There are only a few
steps left in order for all of the panels to be completed. Spray foam needs to be applied in the
inside of the tubing and the grease fittings need to be installed in order for the panels to be
complete.
The estimated cost for the air foil construction and the pulleys for the shaft and
transmission system are listed below:
Supplies: Airfoil ComponentsQuantity Item Source Price
4 4' x 8' Corrugated Plastic Sheet 10mm
Sign World $140.00
8 8’ U Profile Farmtek $5.738 1/8” x 4’ Steel Rods Hardware World $8.714 1” x 1’’ Square
Aluminum Tubing 10’Brumfield Welding $60
Welding Brumfield Welding $40Pins Harbour Freight $10
16 5/16” Aluminum Rods
Bayou Metal N/A
32 Grease Fittings Harbour Freight $20Shipping $39.98
Total $235.96
Supplies: Shaft and
Transmission System Components
Quantity Item Price2 10.25 O.D 1 Bore 1 Groove
Pulley$65.90
1 2.95 O.D. 1 Bore 1 Groove Pulley
$7.75
2 1” Pillow Block Bearing $13.902 50” B V-Belt Type B47
5L500 Classic$12.10
1 70” B V-Belt Type B67 5L700 Classic
$8.35
2 68” B V-Belt Type B65 5L680 Classic
$16.20
Shipping $18.66Total $142.86
Overall Progress:
The initial design phase of the wind turbine was slightly altered to promote a more
simplistic and effective structure design. The mechanism that was responsible for the flipping
action in the beginning of the design phase was the CAM system. Due to limited supplies of
materials and cost-effectiveness, the airfoil schematic was changed. During the process, the
design was finalized, and the plan was to allow the highest resistant airfoil to allow the rotation
to occur, whereas the lowest resistant to flip its airfoils. This setup follows the exact principles
defined earlier on with the CAM setup. Rather than having a complex mechanical system to
initiate the turbine, an unsophisticated design is established. The side with the greatest air
pressure will determine the direction of rotation around the shaft. With this in mind, the
following diagram provides a better visual of how this principle will work in our favor.
Basing off the louver airfoil schematics, a series of airfoils will be installed to a 4’ by 8’
dimension aluminum framework. The center perpendicular aluminum tubing will provide a
structural advantage since the length of each airfoil is rather large. The material is more likely to
undergo a certain amount of stress in the center of the corrugated plastic; in other words, it is
more probable to fail and give way from a high intensity of wind. With regards to the above
diagram, if the specified wind direction were to impact the airfoil from left to right, the lower
end of the airfoils will be laying on top of one another at each of their axis of rotations.
Resistance would then be at its greatest, allowing the airfoils to be pushed by the wind; However,
if the wind direction where to impact from the back side of the airfoil, there is little to no
resistance on the airfoil. The airfoils will flip to permit the wind to pass through. No rotation
will occur from this impact.
An important aspect to the structural stability of the wind turbine will depend highly on
how it is mounted to a base support. The base support was made from steel beams, which are
very sturdy and are typically used as supporting materials. The outer dimensions of the base are
4’ by 4’. This does not put a tremendous amount of weight on the lower portion that will hold
this structure 50+ feet in the air, and it will fit every component needed to make this turbine an
active energy producer.
Along with the base support, there will be a series of guide wire connections that will be
installed to provide even more support in case of excessive wind and to balance the weight of the
airfoils on each end of the shaft. There will be an overall of two different guide wire systems for
this setup: 1) lower shaft to base support and 2) upper shaft to aluminum frame. In addition to
the new airfoil design, a shaft design was also finalized. There will be two shafts used for the
wind turbine: a stationary (outermost) and rotary (innermost) shaft. The main support to hold the
weight of the airfoils and aluminum frame will be accomplished by the stationary shaft. On the
other hand, the rotary shaft will provide the rotations needed to produce the energy from the
movement of the airfoils around the shaft.
References
Wind Blue Power. DC – 540 Low Wind Permanent Magnet Alternator.
www.windbluepower.com. Copyright 2013. Retrieved November 20, 2013.