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The Effects Of Blade Size And Shape On The Electrical Output Of A Generator

Researched by Michael E. 
1999-2000 



PURPOSE

The purpose of this experiment was to determine which windmill blade sizes, shapes, and angles were most efficient at producing an electrical current from a generator.

The information gained from this experiment will help windmill designers and people in rugged areas where the power lines do not reach to determine the optimum size, shape, and angle of windmill blades used to produce electricity.

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HYPOTHESIS

I believe that a trapezoid shaped blade at 75 degrees with the largest surface area will generate the greatest amount of electricity compared to the square, triangle, or rectangular shapes.

I base my hypothesis on internet research and literature that I have read.

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EXPERIMENT DESIGN

The constants in this study were: 
* Same DC amp meter 
* Same windmill 
* Same generator 
* Same fan (wind generator) 
* Same electricity generator 
* Same wind speed 
* Same fan distance (1 meter) from blades

The manipulated variables are the shape, size (blade area), angle, and length of the blades. 

The responding variable was the electrical output of the generator attached to the windmill.  It was measured as milliamps on an amp meter.

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MATERIALS


Quantity
Item Description
1
Windmill
1
Amp Meter
1
Fan (wind producer)
1
Tape Measure
1
Electrical Motor (electrical generator)
24
Blades shaped as a square.  Eight, each with an area of 12.25cm2; eight, each with an area of 49cm2; and eight, each with an area of 98cm2.
24
Blades shaped as a trapezoid.  Eight, each with an area of 12.25cm2; eight, each with an area of 49cm2; and eight, each with an   area of 98cm2.
24
 24 Blades shaped as a rectangle. Eight, each with an area of 12.25cm2; eight, each with an area of 49cm2; and eight, each with an   area of 98cm2.
24
Blades shaped as a triangle. Eight, each with an area of 12.25cm2; eight, each with an area of 49cm2; and eight, each with an   area of 98cm2.

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PROCEDURES

1. Build a windmill out of an erector set, and place it on a piece of wood. The piece of wood acts as the base of the windmill. Attach a motor (1.5 volts) to the erector set with a pulley system connecting the windmill to the motor. The output leads from the motor are hooked to a amp meter to measure the milliamps. 
2. Cut out 24 blades from mat board in each of  these shapes/sizes: trapezoid, triangle, rectangle, and a square at 24.5cm2, 49cm2, and 98cm2 (eight of each). 
3. Place the fan exactly 1 meter from the blades of the windmill. 
4. Place eight trapezoid blades each with an area of 98cm2 on windmill hub.  
5. Set the angle of the blades on the windmill hub to 75 degrees with 0 degrees being perpendicular to the fan blades. 
6. Turn the voltmeter to DC milliamps. 
7. Turn the fan on high. 
8. Read the voltmeter and record the amount of electricity produced in milliamps. 
9. Repeat steps 4-8 using eight of the trapezoid blades each with an area of 12.25cm2 and 49cm2. 
10. Repeat steps 4-8 using eight each of the triangle, rectangular, or square blades at 12.25cm2, 49cm2, and at 98cm2. 
11. Repeat steps 4-10 setting the angle of the blades on the windmill hub to 45 degrees and 60 degrees.  
12. Enter recorded data into a spreadsheet and create graphs.

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PROJECT LOG

Pre-Experiment Log 
October 1, 1999 50 min. 
 I looked at topics for my science project and decided to do a continuation  of last  year’s science project.

October 2, 1999 120 min. 
 I started to look up information on the internet.

October 9, 1999 120 min. 
 I looked up information on encyclopedias.

October 16, 1999 60 min.  
 I looked up information on encyclopedias and the internet.

October 19, 1999 50 min.  
 I perfected my science project topic and started to look up  information for my  research report.

October 23, 1999 10 min.  
 I looked for websites to get information off.

October 30, 1999 120 min.  
 I looked at the websites that I sited.

November 2, 1999 30 min. 
 I looked up information on the internet.

November 6, 1999 20 min. 
 I started to take down notes for my research report,

November 12, 1999 20 min. 
 I looked up information on windmills in the electronic encyclopedias.

November 20, 1999 30 min. 
 I looked up information in the SIS library.

December 7, 1999 120 min.  
 I looked up information on the internet and typed up part of my procedures.

December 14, 1999 30 min. 
 I continued looking up information on encyclopedias and the internet. 

December 16, 1999 20 min. 
 I continued to type my procedures.

December 19, 1999 20 min. 
 I finished a rough draft of my procedures. 

December 30, 1999 125 min. 
 I started to build my windmill. 

January 1, 2000 200 min.  
 I finished building my windmill and tested it.

January 3, 2000 40 min.  
 I worked on making blades for my windmills and got information off the  internet.

January 4, 2000 72 min.  
 I made the trapezoid and triangle blades with a total area of 49cm2.

Experiment Log 
January 6, 2000 120 min.  
  I did my final experiment and collected all the data possible that I  could  collect.  Before starting the experiment I made sure that all of the  nuts'n'bolts were  tight.  I followed all procedures and took care while using the fan.  First I  used  every blade size and blade shape at the angle 75 degrees.  I followed steps 4-8, after  turning on the fan I recorded the results. Next I used every blade size and  shape at  the angle of 60 degrees.   I followed steps 4-8, after turning on the fan I recorded the  results.  Then I used every blade size and shape at the angle of 45 degrees.   I  followed steps 4-8, after turning on the fan I recorded the results.

Post-Experiment Log 
January 17, 2000 150 min. 
 I finished the rough draft of my research report and bibliography.

January 19, 2000 20 min. 
 I started to type the results from in a data spreadsheet.

January 23, 2000 150 min. 
 I started to put my journal together.

February 1, 2000 120 min. 
 I am still puting my journal together.

February 2, 2000 30 min. 
 I am still puting my journal together. 
February 3, 2000 60 min. 
 I am still putting my journal together.

February 5, 2000 30 min. 
 I started to finalize my journal. 

February 6, 2000 
 I started to finalize my project log.

February 7, 2000 
 I finalized my pre-experiment and Experiment log.

February 8, 2000 120 min. 
 I finished my journal.

February 9, 2000 20 min. 
 I cut out my things to put on my display board.

February 10, 2000 
 I started to paste things onto my display board.

February 11, 2000 10 min. 
 I finished my display board.

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RESULTS

The purpose of this experiment was to determine which blade sizes, shapes, and angles on a windmill were most efficient at producing an electrical current from a generator.

The results of this experiment were that the all blades with an area of 98cm2 produced the maximum current of electricity at a blade angle of 75 degrees with zero degrees being perpendicular with the fan blades.  Of all the blades at 75 degrees and with an area of 98cm2, the trapezoid blade was more efficient at producing an electrical current than the triangular, rectangular, and square blades.  As the angle of all the blades declined from 75 degrees to 60 degrees and then to 45 degrees, the production of electricity declined.  At the 60 degree angle, the triangular blades with a surface area of 98cm2  produced a greater amount of electricity than the other three blade shapes.  However, at the 45 degree angle the square blades with a surface are of 98cm2 produced the most electricity than the other three blade shapes.

Every blade shape with an area of 12.25cm2 did not produce any electricity at any blade angle, because the surface area was not large enough to spin the generator.  All the blade shapes with an area of  49cm2 created electricity at all angles except for the trapezoid blades at 75 degrees.   It appears that the 49cm2 trapezoid blades did not turn the windmill due to surface area not being big enough.  However, at 98cm2 surface area, trapezoid blades produced more electricity than the square, rectangular, or triangular shapes.

See the table and graph below. 
 

 

 

 

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CONCLUSION

My hypothesis was that a trapezoid shaped blade at 75 degrees with the largest surface area would generate the greatest amount of electricity compared to the square, triangle, or rectangular shapes.  My hypothesis should be accepted because the greatest amount of electricity was produced with the trapezoid blades with an area of 98cm2 at 75 degrees. 

My experiment demonstrated, that even though my hypothesis was correct, the other blade angles at blade surface areas greater than 98cm2 may actually be better shapes for a windmill than the trapezoid shape.  This would have to be something proven in doing more experimenting with windmills. The windmill that was used in this experiment was not large enough to handle blade areas greater than 98cm2.

With the knowledge I gained from this experiment and if I were to conduct this project again, I would construct a windmill with a larger wind radius so that I could test greater surface area blades.  I would also do multiple tests and I would also verify the wind speed.

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RESEARCH REPORT

Introduction

 Windmills historicaly only did four things: pumped water, ground grain, produced electricity, and just sat for decoration.  Windmills were invented in Persia in the 5th century AD.  In the early years of the 1900’s, there were more than 700 different kinds of water pumping windmills. In the 1930’s a windmill that stood 8 ft. tall cost $25.00.  Today that windmill would cost $1,455.00. Today there are only two types of windmill which are vertical-axis machines and horizontal axis-machines.  Some people say that windmills went out of fashion in the 1940’s.

Modern Windmills

 Windmills today are called turbines which are powered by wind.  Modern windmills are mostly used for creating electricity especially in rugged areas.  The windmill blades are set at an angle so the wind will catch the blades and turn them. Today over 80% of the windmills spin in California, 13% in Denmark, and 2.3% in Hawaii. 

History Of Windmills

 Windmills were discovered at the end of the Roman period.  The first windmills were used to pump water for irrigation or grind grain in Persia around 5th century AD.  By the 12 century AD, windmills were found throughout Europe.  The Dutch built windmills out of wood and canvas.  For centuries the Dutch had relied on windmills for energy and by the 19th century the Dutch had built over 9000 windmills.  In the Netherlands people used windmills to drain water from fields, or to mill grain.  In the 1900’s Americans used windmills to pump water.  In the late 1980’s more than 30 different companies were manufacturing wind machines.  In studies the smaller windmills on the smaller platforms were proven more successful than the bigger windmills on the bigger platforms.  Big windfarms were found to have disruptions such as noise pollution and disruption of radio or television.  The only way that the wind farms create a disruption in habitat are when trees need to be cut down.

Denmark

 By 2030 100% of the power in Denmark is expected to come from windmills.  It will be the largest investment ever made in windmills.  Right now engineers and scientists are finding ways to make offshore foundations strong enough so that the windmills will be able to with stand the force of waves and currents crashing against them. 

Kinds of Windmills

 Today there are only two kinds of turbines, horizontal-axis machines and vertical-axis machines.  There is one more windmill blade that has the principles of an airplane wing to make rotation.  They are driven by wind simply striking the blades.  An example of the horizontal-axis machines are the multi-bladed windmills of the US Prairies.  In the 1920’s George Darrieus a French inventor, invented an efficient wind turbine.  This wind turbine was called the, "Darrieus Wind Turbine".  It had the characteristics of an eggbeater with only two or three carved blades hooked to the vertical shaft.  It would catch the wind from all directions unlike most windmills.

Propellers

 Propeller- A propulsion device usually used on ships and planes.  A propeller 
is a series of blades on a hub that is mounted on an engine-driven shaft (or wind).  The rotation of blades in water or air produces a forward thrust. In the 1920's George Darrieus, a French inventor, invented an efficient wind turbine.  The Mod-2 a government funded test windmill has 91m (300 ft) long propellers.  It is 25 stories tall.

Summary

 The windmill is an invention that dates back to the end of the roman Empire.  There are only two types of windmills, horozontial-axis and vertical-axis.  Understanding windmill design to improve power is important for the future, people will be running off windmills because windmills do not pollute the earth and only create a diruption for the environment if we have to cut down treees.

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BIBLIOGRAPHY

Alexander Llyin, Mary. "Windmill," The World Book Encyclopedia, 1999 
Danish Wind Turbine Manufacturing Association, [Online]  
http://www.windpower.dk/tour/rd/monopile.htm, January 3, 2000 
Landris, Fred. "Bernoullis Principle," Encarta, 2000. 
"Power," Microsoft Encarta, 2000. 
"Powered By Wind," The World Book Encyclopedia, 1998. 
"Windmills," Grolliers Interactive Encyclopedia, 1998. 
Settles, Gary S. "Power," Grolliers Interactive Encyclopedia, 1998. 
"Windmill," Microsoft Encarta, 1999. 
Mr. Brown's MYstical Science Page [Online] Http://www.selah.k12.wa.us/LINKS/olderlinks.html

 


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