The Effect of Blade Length and Shape on the Electrical Out-Put of a Windmill

Researched by Kaylyn F.
2002-03
PURPOSE

The purpose of this experiment was to determine how the length and shape of windmill blades affected the amount of power produced. 

I became interested in this idea when I saw windmills on a family trip. There were different types and I wondered which one produced the most energy.

The information gained from this experiment will be helpful for people who want to generate their own electricity as well as managers of large energy corporations.
 


HYPOTHESIS

My first hypothesis was that the 4 cm. blades would produce a greater amount of electricity than the 12 cm. or 8 cm. blades. My second hypothesis was that the square blades would produce more energy than the regular blades of the same length.

I based my hypothesis on a statement by a previous seventh grade researcher, Ashleigh Buckendal, who said, 
"The longer blade will not produce the most energy, it produces the least. The shortest blades create the most." You can find her research at http://www.selah.k12.wa.us/soar/sci 
 


EXPERIMENT DESIGN

The constants in this study were

 The type of wood used to make the windmill and the blades 
 The generator used to produce electricity 
 The millivoltmeter used to measure the amount of power produced
 by the windmill.
 The height of the windmill
 The angle of the blades, 45°
 The hair dryer used to provide wind
 Distance away from windmill the blow dryer is placed
 The speed of the blow dryer 
 Amount of time for each trial

The manipulated variables were the shape and size of the blades on the windmill. 

The responding variable was the amount of energy produced by the different types of windmill blades.

To measure the responding variable I used a millivoltmeter attached to the windmill’s generator.
 


MATRIALS
QUANTITY ITEM DESCRIPTION
2 90 cm by 0.5 cm balsa wood, square
1 90 cm by 0.5 cm balsa wood, triangular
1  90 cm by 7.5 cm balsa wood, flat
2 90 cm by 1 cm balsa wood, flat
1 Motor that will be used as a generator
1 Blow dryer
1 Hammer
1 Ruler to measure wood and blade length 
1 Millivoltmeter
1 Camera
11 Nails
1 Drill
1 Wooden washer
4 Toothpicks
1 Small metal washer 
1 Stop watch
1 Protractor
1 Weight


PROCEDURES

  1. Build the model windmill with balsa wood 
 a) Measure and mark the support stands to eight inches and the surface area to five inches 
 b) Saw them out and nail the surface onto the support stands
 c) Nail a same sized piece of balsa wood onto the bottom of the support stands
 d) To add weight nail wood to the bottom outer edges, and put a weight in the base
  2. Attach the motor to the windmill 
 a) Nail a piece of balsa wood that is the same width as the generator and is longer than the surface unto the surface area so that the      blades don’t run into the structure of the windmill 
 b) Measure the area to place the generator in 
 c) Screw the generator onto the wood coming out of the surface area
  3. Make the blades 
 a) Measure and mark the 4cm, 8cm and 12cm blades.
 b) Measure and mark the same sizes with the square wood. 
 c) Cut out the pieces.
 d) Drill holes in a wooden washer on the edges at 0°, 90°, 180° and 270° 
 e) Glue toothpicks into the holes and let them dry
 f) After dry cut each toothpick to 2.5 cm 
  4. Attach the 4 cm blades onto the wind mill
 a) On the ends of the toothpicks poke the blades on
 b) Put the washer on the end of the generator 
 c) Make sure that the washer is attached tightly, so it will turn the shaft, attached to the generator.
 d) Put a small metal washer on the end of the shaft.
 e) Attach the wooden washer to the shaft using the middle circle. 
  5. Turn the blades to an angel of 45°
 a) Set a protractor at 45° 
 b) Put the blades in the inside of the angle and move them to 45°
  6. Attach the millivoltmeter to the generator by clipping the long wires to the wires on the generator and turn millivoltmeter on to DC    voltage
  7. Turn the windmill sideways, to the left, to make it turn.
  8. Put a weight in the base so the wind will not blow it over 
  9. Start the stop watch for 30 seconds 
  10. Turn the blow dryer on high aimed at the windmill, keeping the dryer the same distance and height away from the windmill 
  11. Look at electricity produced by windmill on the millivoltmeter
  12. Record the amount of electricity on data sheet 
  13. Take off the 4 cm. blades and attach the 8 cm. blades 
  14. Repeat steps 5 and 7 - 10
  15. Attach the 12 cm blades to the windmill
  16. Repeat steps 5 and 7 - 10
  17. Attach the square 4 cm. blades to the windmill 
  18. Repeat steps 5 and 7 - 10
  19. Attach the square 8 cm. blades to the windmill 
  20. Repeat steps 5 and 7 ? 10
  21. Attach the square 12 cm. blades to the windmill
  22. Repeat steps 5 and 7 - 10
 


RESULTS

The original purpose of this experiment was to see how the size and shape of the blades affected the amount of energy a windmill could produce.

The results of the experiment were the 4 cm. blades produced the most amount of electricity, an average of 56.3 millivolts. The least electricity came from the square 12 cm. blades, with an average of 27.4 millivolts.

See my table and graphs
 


CONCLUSION

My first hypothesis was that the 4 cm blades would produce more electricity than the 8 cm or 12 cm blades. 

The results indicate that this hypothesis should be accepted. The average of the 4 cm blades was greater than the others, in both the flat and the square.

My second hypothesis was that the square cross-sectioned blades would produce more electricity than the flat blades of the same size.

The results indicate that this hypothesis should be rejected. The average of the flat blades was greater than the average of the square blades, though there was so little difference,  it did not really mater.

Because of the results of this experiment, I wonder if even smaller blades would produce more electricity or if they would produce less.

If I were to conduct this project again I would do more trials for each blade type. I would also test another shape of blade.
 


Research Report

Introduction

The burning of fossil fuels like coal and oil are harmful to the environment, but we need them to produce electricity. A windmill uses wind to make clean, un-polluting energy. Creating efficient windmills could reduce pollution.

Windmills

A windmill is a structure that converts wind’s kinetic energy into electricity. This wind power is also used to drive a machine that pumps water or grinds grain, which was what it was originally used for. The electricity made by the windmill’s generator can also be transferred to other places, a person’s home or a factory. The windmill has been used for several thousand years. 
The first windmill is said to have been in the Persian area in 600 AD, used to grind corn. In the seventeen hundreds there were windmills in the Netherlands. In the eighteen hundreds the windmill as used for irrigation, taking the water from the ground where it had flooded from the sea to be used as farming grounds. The first windmill used for power was built in 1890 in Denmark. The windmill helped to develop the western United States. When farmers had electricity made available to them in the 1940’s they did not need their windmills anymore and they let them get run down. The end of the nineteen seventies there were only one hundred fifty thousand left across the United States. When the war came later, oil became short and they had to go back to using wind power. 

Electricity and Energy

The world depends on electricity. It is an essential part of our lives; lighting peoples’ homes and making some of the products we buy in the store by powering the factories. Electricity can be used everywhere since we can transmit it by wires and other sources. There are different types of energy. There is wind, wave, solar power and others. The energy in wind is kinetic energy. It is also the energy in water when it flows. Energy is stored in gas and coal and is released when it is burned. Kinetic energy is in everything that moves. Potential energy is the energy stored up that later becomes kinetic energy when it is needed. 

Volts

Voltage does not kill people as many think, but it is the current that kills or harms people who get electrocuted. 100 AC to 45 DC volts have killed people. The only safe electrical current is 1 milliaperes to 8 milliamperes. There are many companies that sell different types of voltage using devices, such as DATEL or Star Batteries, selling batteries for both AC and DC devices. 

Turbines

A turbine is a machine with a rotor that is turned by a moving fluid like water, steam or wind. The wind turbine is called a windmill. There are varying types of turbines and most are different in size and the amount of power they can produce.  A turbine transforms moving energy, kinetic energy, into power used for machinery like generators. The oldest turbine were the water wheels that were used by the ancient Greeks about two thousand years ago. 

Blades

The blades on a windmill are the things that catch the wind’s movement. They are connected to the shaft. The different kinds of windmills have varying types of blades. The ancient Persian windmills had paddles that were made of bundles of reeds. Some had wooden sails with cloth coverings. The number of blades was also different, though they usually had four. The modern windmill has a three blade propeller. 

Summary

Wind is widely available and there is a lot of it. Wind would not pollute the environment, as other sources of energy do. Wind power has recently become more interesting because of pollution, which is getting worse from burning coal, oil and other substances to create energy. Wind power and windmills would be a good clean source of energy.

 
BIBLIOGRAPHY

Alexander, Mary. "Windmills, " World Book Encyclopedia. 1998.

Division of Community Services. Wind Power. 
   http://www.state.nd.us/dcs/Energy/windhist.html 

Engelbert, Phillis. "Wind Energy," The Complete Weather Resource. 1997.

Gipe, Paul. "Evolution of the Windmill," Microsoft Encarta Deluxe. 2001.

History of Wind Power. November 22, 2002
   http://www.risoe.dk/rispubl/VEA/dannemand.htm 

LeMone, Margaret A. "Wind," World Book Encyclopedia. 2002

Manwell, James F. "Windmill," Microsoft Encarta Deluxe. 2001

Payne, Sherry. A Look Inside Wind and Water Energy. Raintree Publishers Inc. 1983

Stokhuyzen, Frederick. The Dutch Windmill. October 30, 2002
    http://www.tem.nhl.nl/~smits/windmill.htm

Visich, Marian Jr. "Turbine, " World Book Encyclopedia. 1998

Wastson, John. The Windmill Yesterday ? Today - Tomorrow. November 20, 2002. 
     http://buckcreek.tripod.com/windmill.htm 

"What is a Turbine?" World Book’s Young Scientist. 1993

"Wind." Schlessinger. 1998.

"Wind as Energy," Science Encyclopedia. 1997.

Windmill Design and Construction. November 20, 2002. 
    http://servercc.oacton.edu/~wittman/mills/design.htm

"Wind Power," Science Encyclopedia. 1997.

"Work and Energy," The DK Science Encyclopedia.  1993.

 

ACKNOWLEDGEMENTS

I would like to thank the following people for helping me with my science project.

  • My mom helped me design my windmill and nailed the pieces together. She recorded the data on my data sheet from the millivotmeter and picked me up from the after-school classes I attended. 
  • My dad bought the balsa wood for the windmill and also helped to design it. He cut out the words for my title bored and sometimes picked me up at the after-school classes. He also bought me my science board and title board, along with page protectors.
  • My sister helped me trim the paper for my display board and let me use the computer in her room.
  • My other sister offered advice, because she had done a science project in sixth grade, too.
  • Mrs. Hostetler corrected papers and gave advice about how to go about doing the project. During the research part of our experiments, she took us to the school library to take notes. She had us do oral presentations in class to prepare for the science fair.
  • Mr. Newkirk corrected my papers and journal, also, and taught me the correct way of doing my display board and papers. He gave after school classes for our science projects, and before school classes, too. 
  • Mrs. McGarity let me leave class during reading to work on my project with Mr. Newkirk.
  • Mrs. Helms helped me to correct my mistakes, do my graphs and to make my display. She stayed after school at the classes and helped us out.
  • Bryanna and Jessica printed things off the computer for me and cut some of them.



 
 

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