The Effect of Blade Angle and Length on the Electrical Output of a Wind Turbine.

Researched by Erik M.
2001-02


PURPOSE

The purpose of this experiment was to determine how the length and angle that a wind turbine blade is mounted would affect the amount of electricity produced. 

I became interested in this idea when on the news I heard about the need for renewable energy sources and wind power was one of them. 

The information gained from this experiment would help engineers design more efficient blades for wind turbines.


HYPOTHESIS

My first hypothesis was that the wind turbine with the blades mounted at a forty-five degree angle would produce the most electricity.

I base my first hypothesis on the fact that a blade mounted at a zero or ninety degree angle will not create any or little movement so a blade mounted at forty-five degrees (half way in between) will probably work the best. 

My second hypothesis was that the wind turbine with the longer blades would produce the most electricity. 

I base my second hypothesis on a website called "Ventura County Science Fair Lab Report: Optimizing Windmill Blade Efficiency" that states, "Larger blades have a greater swept area and thus catch more wind with each revolution. This website can be found at http://www.west.net/vcsf/windmill.htm.


 EXPERIMENT DESIGN

The constants in this study were:

 The number of blades each turbine had (3).
 The wind speed.
 The wind source (electric fan).
 The amount of time each blade design was tested (30 seconds)
 The DC motor used.
 The basic wind turbine tower.
 The materials used to make each blade.
 The direction the wind source is blowing.
 The room in which the experiment took place.
 The multimeter used to measure electricity.

The manipulated variables were the length, and angle that the blades were mounted on the wind turbine. 

The responding variable was the amount of electricity produced from the DC motor hooked up to the wind turbine. 

To measure the responding variable I used a multimeter that used milli-volts to measure the amount of electricity produced. 


MATERIALS
QUANTITY  ITEM DESCRIPTION
1 DC Motor
1 bottle Insta-Cure Glue
1 Digital Multimeter
1 Snap Saw
1 Exacto Knife
1 Protractor
1 5/16 inch x 5/16 inch x 36 inch balsa wood rods
2 3/16 inch x 3/16 inch x 24 inch bass wood rods
1 1/8 inch x 3 inch x 24 inch bass wood board
1 1/16 inch x 4 inch x 24 inch bass wood board
2 1/32 inch x 3 inch x 36 inch balsa wood board
1 Drill
1 42 cm x 42 cm pegboard
1 Electric Fan
1 Pen or Marker
1 Meter Stick
1 Timer
5  Craft Circles
2 Alligator Clips


 PROCEDURES

Build the Windmill Tower
1. Cut a 42cm x 42cm square out of pegboard for the base of the wind turbine tower and set aside.
2. Cut each of the two bass wood rods in half to form four smaller rods and also set aside.
3. Cut four 5cm x 30.5cm pieces out from the 1/16 inch x 4 inch x 24 inch bass wood board. Set aside.
4. Using Insta-Cure glue, glue the four 5cm x 30.5cm bass wood pieces to the four bass wood rods so that the four rods are the corners and the rectangles form the walls. This will be the tower that the DC motor rests on. The tower should be 30.5cm tall, 5cm wide and 5cm deep. 
5. Put some of the Insta-Cure glue around the bottom edge of the tower and glue it in the center of the 42cm x 42cm base. 
6. Cut a 5cm x 5cm square out of 1/8 inch x 3 inch x 24 inch basswood.
7. Use the Insta-Cure glue to glue the DC motor onto the edge of the 5cm x 5cm square so that the shaft goes over the edge of the tower. 
8. Put glue around the top edge of the tower and glue the square with the motor attached to it to the top of the tower. 
Blade Angle
9. In three of the craft circles drill a small hole in the center so that the shaft of the motor will fit tightly through it.
10. Cut five, 2cm long pieces from the 5/16 inch x 5/16 inch x 36 inch balsa wood rods.
11. Cut two of the 2cm long pieces in half horizontally, lengthwise to form four right triangles that have a 45° slope. Only three of the four will be used. 
12. Cut the other three 2cm long pieces slightly off from diagonal so that one part forms 60° slopes and the other part forms a 30° slope. 
13. Glue three of the 45° triangles onto one of the circles from step 9. Glue them flush to the edge of the circle so that one of the narrow ends of the triangles are facing the center and the 45° slopes are all facing in a counter clockwise direction.
14. Repeat step 15 with the 60° and 30° slopes and the other two circles from step 9.
15. Out of the two 2 1/32 inch x 3 inch x 36 inch balsa wood boards cut out nine 3.8 cm x 15 cm blades with the Exacto knife.
16. Glue the back 2 cm of the bottom left corner of the three blades onto the three 45° slopes so that the blades are protruding outward from the center. 
17. Repeat step 18 with the other six blades and the 30° and 60° slopes.
18. Connect the digital multi-meter to the DC motor with the two alligator clips.
19. Take the blade circle with the 45° slopes and press it onto the front of the motor shaft.
20. With the pen or marker mark the motor shaft and the blade circle so that you can tell if the circle slips during the experiment.
21. Position the electric fan 42cm away from the end of the wind turbine’s base. Make sure that the multi-meter is ready and that a timer is set for thirty seconds.
22. Start the timer and turn on the electric fan. When thirty seconds has passed press the data hold button on the multimeter and record data.
23. Repeat steps 19-22 for the 30° and 60° slopes and record data.
24. Repeat steps 19-24 two more times so there are three trials for each blade circle.
Blade Length
30.Repeat step 9 with the remaining two circles.
31.Make six more blade angles at 30, 60, or 90 degrees depending on which did the best during the blade angle tests.
 32.Repeat step 13 to glue the six angled slopes to the last two circles.
33.Cut three 3.8 cm x 12 cm pieces and three 3.8 cm x 18 cm pieces from the two 2 1/32 inch x 3 inch x 36 inch balsa wood boards. 
34. Glue the back 2 cm of the bottom left corner of the three 3.8 cm x 12 cm blades onto the three slopes on one of the two circles from step 30 so that the blades are protruding outward from the center.
35. Glue the back 2 cm of the bottom left corner of the three 3.8 cm x 18 cm blades onto the three slopes on the other circle from step 30 so that the blades are protruding outward from the center.
36.Repeat steps 19-24 with the blade circles made in steps 30-35 and record data.


  RESULTS

The original purpose of this experiment was to determine how the length and angle that a wind turbine blade is mounted would affect the amount of electricity produced.

The results of the experiment were that the wind turbine with blades mounted at a 30 degree angle did the best, producing 45.4 milli-volts of electricity on average. As the size of the angle increased the amount of electricity being produced decreased. The wind turbine with blades at 45 degree angles produced 33.3 milli-volts of electricity on average and the wind turbine with blades at 60 degree angles produced 19.63 milli-volts of electricity on average. The wind turbine with blades that were 12cm long did the best, producing 57 milli-volts of electricity on average. The wind turbine with the blades that were 15cm long produced 33.3 mill-volts on average and the wind turbine with blades that were 18cm long produced 34.5 milli-volts of electricity on average. 

View My Data and Graphs


 CONCLUSION

My first hypothesis was that the wind turbine with the blades mounted at a forty-five degree angle would produce the most electricity.

The results indicate that my first hypothesis should be rejected because the blades that were mounted at a 30° angle produced about 25 more milli-volts of electricity than the blades mounted at a 45 degree angle. 

My second hypothesis was that the wind turbine with the longer blades would produce the most electricity.

The results indicate that my second hypothesis should also be rejected because the blades that were 12cm long (the shortest tested) produced about 23 more milli-volts of electricity than the blades that were 18cm long (the longest tested). 

Because of the results of this experiment, I wonder if the shape and material that the blades are made out of and the number of blades would affect the amount of milli-volts produced. 

If I were to conduct this project again I would have tested all of the sizes of blades with all of the different angles instead of just testing each size with the angle that did the best. I would have also tested some other angles and sizes and I would have had more trials.


 
 

RESEARCH REPORT

INTRODUCTION

As the population of the earth grows and the number of machines that use electricity increases the earth’s supply of fossil fuels and other limited energy sources are being rapidly depleted. If we continue to use these limited energy sources at the rate that we currently are we will run out in the fairly near future. We use electricity everyday for ovens, lights, television, computers, and heat. The world is now looking to renewable energy sources such as solar power, hydroelectric power, and wind power for our electricity needs. Scientists are now looking to perfect these renewable energy sources so that they are as efficient as possible.

WIND

How is Wind Caused?
Wind is air moving across the surface of the earth. It can be strong such as a hurricane or soft such as a light breeze. The uneven heating of the earth by the sun causes wind. The air in the warm areas rise and the air from the cooler areas then rush to replace it. The rising hot air cools down and lowers while the cool air gets warm and rises. This is called circulation and this moving of air is wind. Circulation can occur in small areas or large areas. 
Measuring Wind
Speed and direction are used to describe wind. Wind direction is measured using a weather vane or a windsock and indicated using the 360 degrees of a circle. It is named according to the direction it is blowing. The speed of wind is measured using an instrument called an anemometer. An anemometer is a set of cups attached to a shaft with rods. The cups catch the wind and spin the shaft. The speed is measured by the speed of the spinning shaft. In the United States wind is measured in miles per hour and knots, but in other countries it is measured in kilometers per hour. The Beaufort scale is a series of numbers that are used to indicate wind speed. The numbers range from zero to seventeen, zero being calm and seventeen being a strong hurricane. Satellites and helium filled balloons are also used to measure wind.

WINDMILLS AND WIND TURBINES

The Basics of Windmills and Wind Turbines
A windmill is basically a machine operated by the power of wind and a wind turbine is a modern windmill that is used to create electricity. Wind turbines usually have two to three blades, which are attached to a rotor at an angle so that they turn when wind blows against them. The rotor is attached to a horizontal shaft, which is attached to a tower. When the wind turns the blades and rotor the rotor turns the shaft. The power from the turning shaft goes through a set of gears to a vertical shaft. The power of the turning vertical shaft transmits to a generator where is changed into electricity. The windmill is the same except its power is used to do things like pump water or turn grindstones. There are two types of wind turbines horizontal axis and vertical axis. 
The History of Windmills
The Egyptians were most likely the first people to use wind energy. They harnessed the power of the wind with sailboats. In the 600’s A.D. Persian people made the first actual windmills. Theses windmills were on a vertical axis and were mainly used to grind grain. In the twelfth century windmills came to Europe. There, inventors and scientists discovered that windmills with a horizontal shaft were more efficient than the vertical axis windmills of Persia. In Europe windmills were used mainly by the Dutch to mill grain and drain water from fields. Windmills came to America during the 1800’s. Americans used windmills mostly to pump water. Wind turbines have been used to generate electricity since the early 1900s.
Wind Power
Wind power is energy that has to do with air moving over the earth. Wind is a renewable form of energy that is clean and doesn’t cause pollution. Scientists think that if people could capture 10% of the wind’s kinetic energy that that it could power the entire earth. Scientists also theorize that it is only possible to extract 59% of the wind’s kinetic energy. In 1990 there were about 25,000 turbines being used. Wind turbines supply only 0.1% of the world’s power.

ELECTRICITY

The Basics of Electricity
The World Book Encyclopedia says that, "Electricity is a fundamental force of the universe." Electricity is very important. It makes things such as televisions, computers, and lights possible and electric force is what holds atoms and molecules together. In the 19th century people first learned to use electricity to do work for them. Electricity is used to produce three main things: motion, heat, and light. Electricity is used in homes, industry, transportation, and communication.
Protons, Neutrons, Electrons, and Quarks
 Everything is made up of electrons, protons and neutrons. Protons and neutrons and each made up of two quarks. Protons and electrons all have an electric charge of either positive, or negative. Electrons have a negative charge and protons have a positive charge. Opposite charges (negative and positive) attract each other and like charges repel one another. This repelling and attracting is caused by invisible electric fields. Protons, neutrons, and electrons combine to form atoms. The protons and neutrons make up the nucleus, which has a positive charge. The electrons circle around the nucleus. There is usually the same number of protons as there are electrons, because of this the atom is neutral. Ions are atoms that have gained or lost an electron so that they have either a positive or negative charge. Negative and positive ions attract one another to form solid objects. An object has an electric charge if a large number of atoms lose or gain electrons at the same time. A current is the flow of electric charge through a conductor. This electrical energy can be used for many tasks when converted. 
The Volt
The volt is the metric system’s unit of measure for electricity. The World Book Encyclopedia says that, "A volt can also be defined as the difference in electric potential between two points on a wire that is carrying 1 ampere of current and producing one watt of power." The volt was named after the Italian scientist, Alessandro Volta. A voltmeter is used to measure volts.
Electric Generators
An electric generator is a device that produces electricity. There are two types of generators, direct current (DC) and alternating current (AC). DC generators produce electric current that always flows in the same direction, while (AC) generators produce electric current that changes direction several times per second. Generators must be driven by something that produces mechanical energy such as a wind turbine. Prime mover is what engineers often call the device that produces mechanical energy. The generator changes the mechanical energy into electrical energy. Generators produce electricity by moving a coil of copper wire around a magnet or moving a magnet around a coil of copper wire. This was discovered by two physicists, Michael Faraday and Joseph Henry in the early 1830’s. 
 

BIBLIOGRAPHY

Berry, Mark. Windmill World. November 13, 2001 http://www.windmillworld.com/

Gipe, Paul. "Wind Energy." Encarta. 2001.

Ghandakly, Adel A. "Wind Power." The World Book Encyclopedia. 1999.

Ilyin, Mary Alexander. "Windmill." The World Book Encyclopedia. 1999.

LeMone, Margaret A. "Wind." The World Book Encyclopedia. 1999.

"Optimizing Windmill Blade Efficiency." Ventura County Science Fair. November 19, 2001. http://www.west.net/~vcsf/windmill.htm

Prigo, Robert B. "Volt." The World Book Encyclopedia. 1999.

Visich, Jr., Marian. "Turbine." The World Book Encyclopedia. 1999.

"Wind Power." Young Scientist. 1997. Volume 8, Energy Conservation. P. 52- 53.

"Windmills and Wind Power." Academic American Encyclopedia. 1998.

Wolfson, Richard. "Electricity." The World Book Encyclopedia. 1999.
 

Acknowledgements and Thanks

This science project could not have been possible without the help and assistance of several people. I would like to thank each of them for their help.

My mom drove me to several stores to purchase materials for my project. She also helped me with anything that needed a second pair of hands during my experiment.

My dad paid for all the materials needing for building the wind turbines.

The employees at the Cloverleaf for spending almost an hour helping me find the materials.

Mrs. Helms for teaching me how to do various things related to the science projects and for giving me advice and encouragement.

Mr. Newkirk for staying after school so that I could finish my science project and he gave me advice on what to fix or change on my project. He also taught me how to do a science project. 

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