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Researched by Ashleigh B.
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The purpose of this experiment was to determine how blade design factors (length and pitch) will affect the energy produced by a windmill at various wind speeds.
I became interested in this idea when I went to Iowa last summer and observed the newly built wind turbines. I began wondering how different wind speeds would effect the output.
The information gained from this experiment will benefit society by
producing a safer and more efficient way to create energy. Most current
ways of producing energy also create pollution. Wind is a non-polluting
energy source people may need in the future.
My first hypothesis is that a longer blade will produce more energy regardless of wind speed. My second hypothesis is that a blade with a pitch closer to 45 degrees will be more efficient than a higher or lower pitch blade. My third hypothesis is that lower wind speeds will create a lower energy output.
I base my first hypothesis on a statement in Encarta Encyclopedia that said, "in low wind environments longer blades produce more energy." I base my second hypothesis on the fact that a pitch of zero degrees will not producing any movement, which is also true for 90 degrees. So, halfway in the middle (45 degrees) should produce the most energy. The third hypothesis is based on "common sense" and my observations that low winds create less energy than high wind speeds.
The constants in this study were:
- The fan used to create wind
- The blades’ same surface area
- The model windmill
- The saw for cutting the wooden disks at various angles.
- The ruler used to measure the length and width of the blades
- The generator for creating electricity
- The multimeter used to measure the voltage
The manipulated variables were the low and high wind speeds, tested
using three different blade lengths, and three different blade pitches.
The responding variable was how much electricity was produced using each blade.
To measure the responding variable a Craftsman auto-ranging digital multimeter was used to measure the voltage that each blade produced.
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QUANTITY |
ITEM DESCRIPTION |
| About 56 | craft or Popsicle sticks |
| 3 | pieces balsa wood |
| 1 | digital multimeter |
| 9 | wooden craft circles |
| 1 | motor that will be used as a generator |
| 1 | glue gun |
| 1 | tube of Future Glue for gluing blades into place |
1. Build the model windmill out of wooden craft sticks and balsa wood.
2. Attach to the motor, the disk with the 18-centimeter by 2-centimeter
blades that are set at a pitch of 15 degrees.
3. Turn the fan on low for 1 minute, and take the highest reading that
came out during that time.
4. Record energy output from the multimeter.
5. Turn fan on high and repeat steps 2,3, and 4.
6. Attach to the motor, the disk with the 12-centimeter by 3-centimeter
blades that are set at a pitch of 15 degrees.
7. Repeat steps 2, 3, and 4.
8. Attach to the motor, the disk with the 9-centimeter by 4-centimeter
blades that are set at a pitch of 15 degrees.
9. Repeat steps 2, 3, and 4.
10. Attach to the motor, the disk with the 18-centimeter by 2-centimeter
blades that are set at a pitch of 30 degrees.
11. Repeat steps 2, 3, and 4.
12. Attach to the motor, the disk with the 12-centimeter by 3-centimeter
blades that are set at a pitch of 30 degrees.
13. Repeat steps 2, 3, and 4.
14. Attach to the motor, the disk with the 9-centimeter by 4-centimeter
blades that are set at a pitch of 30 degrees.
15. Repeat steps 2, 3, and 4.
16. Attach to the motor, the disk with the 18-centimeter by 2-centimeter
blades that are set at a pitch of 45 degrees.
17. Repeat steps 2, 3, and 4.
18. Attach to the motor, the disk with the 12-centimeter by 3-centimeter
blades that are set at a pitch of 45 degrees.
19. Repeat steps 2, 3, and 4.
20. Attach to the motor, the disk with the 9-centimeter by 4-centimeter
blades that are set at a pitch of 45 degrees.
21. Repeat steps 2, 3, and 4.
22. Repeat entire process two more times in order to make experiment
results more reliable.
The original purpose of this experiment was to determine how blade design factors (length and pitch) would affect the energy produced by a windmill at various wind speeds.
The results of the experiment were that when the 18 centimeter by 2 centimeter blades were set at a pitch of 15 degrees they produced an average of 90 millivolts when the fan was set on high and 62 millivolts when set on low. When the same blades were at a pitch of 30 degrees they created an average of 106 millivolts (high) and 72 millivolts (low). Also, when these blades were set at a pitch of 45 degrees they produced an average of 122 millivolts (high) and 86 millivolts (low).
When the 12 centimeter by 3 centimeter blades were set at a pitch of 15 degrees they had an average output of 146 millivolts (high) and 95 millivolts (low). When the blades were set at 30 degrees they produced an average of 200 millivolts (high) and 137 millivolts (low). When set at 45 degrees the blades created an average of 241 millivolts (high) and 169 millivolts (low).
The 9-centimeter by 4-centimeter blades, set at 15 degrees, produced an average of 183 millivolts (high) and 114 millivolts (low). When set at 30 degrees the blades created an average of 269 millivolts (high) and 177 millivolts (low). The blades set at 45 degrees had an average output of 316 millivolts (high) and 206 millivolts (low).
The overall average of all of the blades was 155 millivolts, both high and low combined. The average for the blades tested at the high speed was 179 millivolts. When tested at the low speed the average millivoltage was 124.
See the graph below.
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My hypothesis was that a longer blade would produce more energy regardless of wind speed. My second hypothesis was that a blade with a pitch closer to 45 degrees would be more efficient than a higher or lower pitch than 45 degrees. My third hypothesis was that lower wind speeds would create a lower energy output.
The results indicate that my first hypothesis should be rejected. The longest blade did not produce the most energy, in fact it produced the least amount. While the shortest blade created an average of 316 mill-volts of energy the longest blade produced an average of 122 milivolts.
My second hypothesis should be accepted. The blades set at a pitch of 45 degrees all had a greater energy output then that of 15 or 30 degrees.
My third hypothesis should also be accepted because when the fan was set on the lower speed the energy output was always lower than when it was set on high.
Because of the results of this experiment, I wonder if the materials I used to make the blades effected the energy output. If I had used a different material would the results have been different? Also, the blade shape might make a difference in the energy output. Wind energy companies today use high tech and unique shapes as their blades.
If I were to conduct this project again I would use a gear reduction system to see if the voltage would be higher than it was now. Possibly, I would also use a controlled wind source. High and low speeds on a fan are not controlled; high is not necessarily twice as strong as the low speed. I wonder if the speed was doubled, would the energy output double as well? What if it was to be tripled? And so forth.
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