Project OVERLOAD
Friday, April 17, 2009
Brad Eckel
Riley Exum
Jordan Harris
Blake Vaughn
Team 7
EF 152 B2

Abstract
Engineering Fundamentals 152 Team Project 4 was to construct a windmill powered by a fan that would light a one and a half volt light bulb. The requirements were the windmill had to fit in a half meter cubed space, could cost no more than forty dollars to construct, and must be completed by April 21 st
.
None of the requirements posed a threat for team seven. The windmill easily fits in the space, cost a little over twenty-eight dollars to build, and was completed well ahead of time.
Actual power, theoretical power, and efficiency were the three main figures used to determine the quality of the generator. With a consistent voltage of nine volts, which was nearly nine times greater than the next best in the section, and thirty-six percent efficiency, the windmill was deemed a success.
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Introduction
This project began when the Engineering Fundamentals 152 instructors challenged the class to design and construct a magnetic generator that would be powered by wind from a fan. The generator was to power a one and a half volt light bulb from an estimated velocity of twenty miles per hour of air. A generator would have to be used to change the mechanical energy of the air into the electrical energy needed to power the light bulb.
Background
A generator is a device which converts mechanical energy from motion into electrical energy. Generators do not create electricity. Electricity is present in wires, and a generator merely causes it to move ("Electrical Generator").
Electromagnetic induction, the movement of a magnet relative to a stationary conductor, or vice versa, is one way to create a generator. The concept of electromagnetic induction was independently developed by Michael Farday and Joseph
Henry in 1831 ("Faraday's Law of Induction").
After learning these principles of electricity, an approach to solving the problem was formulated. How it was implemented will be the topic of the next section.
Design and Process
Upon learning how electromagnetic induction works, we determined we would need magnets, a conductive wire, and something to spin the magnets with. Because the generator was to be powered by a fan, our logical choice to spin the magnets was some type of blade. To determine the proper wire, research was done, and the final decision was made for thin, coated copper wire. A decision was also made to purchase a higher
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gauge wire. A lower gauge wire does carry a higher current-carrying capacity, but with its smaller diameter more high gauge wire can be used and it is also more flexible to work with ("American Wire Gauge").
One member of the group made the most important realization for the team when determining a more powerful magnetic field would matter more than the speed at which the field moved. With this fact in mind rare earth magnets were purchased. Rare earth magnets are made of rare earth elements which have incompletely filled f-shells ("Rare-
Earth Magnet"). These elements can be found in Lanthanide series on the period table.
Our particular magnets are Neodymium magnets and are extremely strong.
Once the parts for the generator had been obtained all that was left to do was construction. Because of the foresight we had construction took only one night. The magnets were attached to a rod with their poles in opposite directions using a two-sided adhesive. This “axle” was then placed between two bearings in identical pieces of wood at an identical height. A piece of wood was then stapled to each of the pieces the “axle” ran through on the top and bottom to stabilize it and hold it in place. Two washers were then used to keep the “axle” in a stationary position between the pieces. Two hundred feet of copper wire was then coiled around the two pieces of wood parallel to the axle.
The coil is now oriented perpendicular to the spin of the magnets. Two screws were added and the two ends of the wire were wrapped around them for both aesthetics and ease of use. Finally a model airplane propeller was attached to the “axle”.
Device Description
*Device sketches are attached.
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The windmill was designed so that the “axle” would experience the minimum amount of friction and resistance. The propeller is from a model airplane and is nine inches long and one inch wide at it’s widest point (in calculating the area it was over estimated to be nine square inches). The framework around the axle is made up of scrap wood spray painted blue for aesthetics. Attached to the axle are two magnets and wound around the framework supporting it is two hundred feet of copper wire. The axle is held in place by two washers and epoxy.
The magnets are neodymium magnets. Neodymium magnets are part of a group of magnets called rare earth magnets. This group is made up of elements with an incompletely filled f-shell.
The copper wire is thirty gauge wire which has a very small diameter. An extremely thin coating also surrounds the wire which results in an even lower loss of current.
Analysis
The theoretical power of the generator is found by using the wind speed of the fan powering the generator.
Ρ =
Α
V 3
1
2
Variables
Cross Sectional Blade Area
Wind Speed
Constants
Density of Air
0.00581 m²
8.94 m/s
1.2 kg/m²
Actual power is measured using current and voltage.
Ρ = Ι
V
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Both of these variables were actually measured using a multimeter during the final testing and presentation of the windmills.
Experimental
Voltage
Current
0.9 Volts
0.1 Amps
Because of the strong magnetic field produced by the generator, the efficiency was quite high relative to the other teams. The efficiency was calculated by merely dividing the actual power by the theoretical power.
Efficiency
=
Ρ
Actual
Ρ
Theoretica l
Power
Theoretical
Actual
Efficiency
2.491 Watts
0.900 Watts
36.13%
Even though the efficiency experienced was high it could have been taken higher by making a couple minor changes. One easy way would have been to increase the angular velocity of the magnets. After completion it was determined the magnets on the
“axle” were not balanced. This caused added friction when the “axle” turned resulting in a lower angular velocity of the magnets. This defect also hampered the start by making the initial turn require a much greater moment if the heavier side was facing downwards.
This minute adjustment would result in great improvements in not only the startup time of our generator, but its overall performance as well.
Bill of Materials
All the materials were easily obtainable except copper wire. It took several days to obtain wire and it hindered progress for several days. The Neodymium magnets were
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found on the internet. The miscellaneous items were all accumulated by a team member.
The propeller used is not factored into the bill because it was not damaged or altered in anyway therefore it can be removed after finishing and used again for its original purpose unchanged.
Bill of Materials
Purchases
Rare Earth
Magnets
Cost ($)
7.95
Copper Wire 14.99
2.12 Tax
Miscellaneous
Wood
Spray Paint
2
1
Screws
Total
0.5
28.56
Conclusions
In a real world context, the two most important aspects of a windmill would be its efficiency and its cost. The final determining factor would be those two factors related to each other, cost versus efficiency. In terms of those two factors Project OVERLOAD was a tremendous success. It cost only $28.56 to build and had a high efficiency of
36.13%. The design used might not be the best for a full scale windmill, but works very well when considering the restrictions, resources, and time allowed.
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Works Cited
"Electrical Generator." Wikipedia. 2009. Wikipedia. Web.22 Apr 2009.
<http://en.wikipedia.org/wiki/Electrical_generator>.
"Faraday's Law of Induction." Wikipedia. 2009. Wikipedia. Web.22 Apr 2009.
<http://en.wikipedia.org/wiki/Electromagnetic_induction>.
"American Wire Gauge." Wikipedia. 2009. Wikipedia. Web.22 Apr 2009.
<http://en.wikipedia.org/wiki/American_wire_gauge>.
"Rare-Earth Magnet." Wikipedia. 2009. Wikipedia. Web.22 Apr 2009.
<http://en.wikipedia.org/wiki/Rare_earth_magnet>.
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